appendix f noise and vibrationtechnical report - valley metro...appendix f . noise and...

Appendix F

Noise and Vibration Technical Report

Environmental Assessment May 2015 Tempe Streetcar

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Environmental Assessment May 2015 Tempe Streetcar

TABLE OF CONTENTS

SECTION PAGE LIST OF TABLES ..................................................................................................................... II LIST OF FIGURES .................................................................................................................. IV

1.0 INTRODUCTION ........................................................................................................... 1 1.1 Background .......................................................................................................... 1

2.0 SUMMARY ..................................................................................................................... 6 2.1 Noise Assessment Approach ................................................................................ 6 2.2 Vibration Assessment Approach ........................................................................... 7 2.3 Noise Concerns Associated with the Streetcar System ........................................ 8 2.4 Vibration Concerns Associated with the Streetcar System ................................. 10 2.5 Summary of Noise Impact Analysis .................................................................... 11 2.6 Summary of Vibration Impact Analysis ............................................................... 13 2.7 Summary of Construction Noise and Vibration Impact analysis ......................... 15

2.7.1 Construction Noise .................................................................................... 15 2.7.2 Construction Vibration ............................................................................... 16

3.0 INVENTORY OF NOISE- AND VIBRATION-SENSITIVE SITES ............................ 18

4.0 AFFECTED ENVIRONMENT..................................................................................... 18 4.1 Existing Conditions - Noise ................................................................................. 19 4.2 Existing Conditions – Vibration ........................................................................... 24

5.0 REGULATORY FRAMEWORK ................................................................................. 25 5.1 State and Local Noise and Vibration Limits ........................................................ 25 5.2 FTA Noise Impact Criteria .................................................................................. 25 5.3 FTA Impact Criteria for Groundborne Vibration .................................................. 30

6.0 NOISE AND VIBRATION METHODOLOGY ............................................................ 35 6.1 Noise Prediction Model ....................................................................................... 35

6.1.1 Noise from Streetcar Operations ............................................................... 35 6.1.2 Prediction Model, Noise from Audible Warnings ........................................ 37 6.1.3 Ancillary Equipment ................................................................................... 38 6.1.4 Road Traffic Analysis ................................................................................. 38

6.2 Vibration Prediction Model .................................................................................. 38 6.2.1 Vibration Propagation Test Procedure ....................................................... 41 6.2.2 Vibration Propagation Test Sites ............................................................... 42 6.2.3 Applying Vibration Propagation Test Results to Prediction Model ............. 44 6.2.4 FDL ............................................................................................................ 46 6.2.5 Adjustments of Lv for Prediction Model ..................................................... 47 6.2.6 Final Vibration Prediction Model ................................................................ 50 6.2.7 Special Land Uses ..................................................................................... 50

Noise and Vibration Technical Report Page i May 2015 Environmental Assessment Tempe Streetcar

7.0 POTENTIAL OPERATIONAL NOISE AND VIBRATION IMPACTS AND MITIGATION ............................................................................................................... 52

7.1 Streetcar Related Noise ..................................................................................... 52 7.1.1 Operational Noise ...................................................................................... 52 7.1.2 Ancillary Equipment ................................................................................... 56

7.2 Traffic Noise Due to Roadway Changes AND TRAFFIC VOLUME INCREASES58 7.3 Streetcar Operational Vibration .......................................................................... 59 7.4 Operational Noise Mitigation .............................................................................. 63 7.5 Operational Vibration Mitigation .......................................................................... 64

8.0 POTENTIAL CONSTRUCTION NOISE AND VIBRATION IMPACTS AND MITIGATION ............................................................................................................... 65

8.1 Construction Noise ............................................................................................. 65 8.2 Construction Vibration ........................................................................................ 66 8.3 Construction Noise Mitigation ............................................................................. 68 8.4 Construction Vibration Mitigation ........................................................................ 68

9.0 REFERENCES ........................................................................................................... 70

APPENDIX A FUNDAMENTALS OF NOISE AND VIBRATION .................................... 71 A.1. Noise Fundamentals ........................................................................................... 71 A.2. Vibration Fundamentals ...................................................................................... 73

APPENDIX B FORCE DENSITY MEASUREMENT RESULTS ..................................... 76 B.1. Seattle Streetcar Measurements ........................................................................ 76 B.2. Portland Streetcar measurements ...................................................................... 87 B.3. Rail Roughness Measurements .......................................................................... 92 B.4. Force Density Calculations ................................................................................. 95

APPENDIX C STREETCAR NOISE MEASUREMENT RESULTS ................................ 97

APPENDIX D VIBRATION PROPAGATION TEST RESULTS ...................................... 99 D.1. Photos of Vibration Propagation Sites .............................................................. 100 D.2. Test Diagrams of Vibration Sites ...................................................................... 108 D.3. Measured LSTM and Coherences at Each Site ................................................ 113 D.4. LSTM Coefficients for Each Site ....................................................................... 121

APPENDIX E AMBIENT NOISE MEASUREMENT SITES ........................................... 126

APPENDIX F SENSITIVE RECEIVER INVENTORY .................................................... 134

List of Tables Table 1: Tempe Streetcar At-A-Glance ........................................................................... 3

Table 2: Stop Location By Type ...................................................................................... 4

Table 3: Traction Power Substations Location Options ................................................... 4

Table 4: Summary of Predicted Noise Impacts and Mitigation For Streetcar Operations ..................................................................................................................... 13

Noise and Vibration Technical Report Page ii May 2015 Environmental Assessment Tempe Streetcar

Table 5: Summary of Predicted Vibration Impacts and Applicable Mitigation ................ 15

Table 6: Summary of Existing Noise Measurements ..................................................... 24

Table 7: FTA Land Use Categories and Noise Metrics ................................................. 26

Table 8: FTA Noise Impact Criteria ............................................................................... 29

Table 9: Interpretation of Vibration Criteria for Detailed Analysis .................................. 32

Table 10: Groundborne Noise and Vibration Impact Criteria for Special Buildings ....... 32

Table 11: Comparison of Indoor airborne and Groundborne Noise Levels ................... 33

Table 12: Proposed Streetcar Operating Schedule ....................................................... 36

Table 13: LSTM Coefficients for Prediction Model ........................................................ 46

Table 14: Summary of Noise Impact Assessment For Category 1 ................................ 53



Table 17: Predicted TPSS Noise ................................................................................... 58

Table 18: Summary of Vibration Impact Assessment for Category 2 ............................ 60

Table 19: Summary of Vibration Impact Assessment For Category 3 ........................... 62

Table 20: Summary of Vibration Impact Assessment For Special Buildings ................. 63

Table 21: Summary of Vibration Mitigation .................................................................... 64

Table 22: Construction Noise Guidelines ...................................................................... 65

Table 23: Predicted Construction Noise ........................................................................ 66

Table 24: Construction Vibration Damage Risk Criteria ................................................ 67

Table 25: Construction Vibration Predictions ................................................................ 67

Table 26: Line Source Transfer Mobility Coefficients, Site V-3 ................................... 121



Noise and Vibration Technical Report Page iii May 2015 Environmental Assessment Tempe Streetcar


Table 30: Line Source Transfer Mobility Coefficients, Site V-11 ................................. 124




Table 34. Sensitive Receiver Inventory ....................................................................... 134

List of Figures

Figure 1: Build Alternative ............................................................................................... 2

Figure 2: Map of Noise and Vibration Test Sites ........................................................... 19

Figure 3: FTA Noise Impact Criteria .............................................................................. 28

Figure 4: FTA Criteria for Detailed Vibration Analysis ................................................... 31

Figure 5: Schematic of Vibration Propagation Test ....................................................... 41

Figure 6: Measured LSTM at 25 ft and Max, Min, Avg LSTM at 25 ft ............................ 45

Figure 7: Best fit LSTM – Max, Min, Avg of All Sites ..................................................... 45

Figure 8: Streetcar Force Density Level at 25 mph ....................................................... 47

Figure 9: Indoor Vibration Amplification, 1st (Ground) Floor ......................................... 49

Figure 10: Indoor Vibration Amplification, 2nd Floor ..................................................... 49

Figure 11: Predicted Streetcar Vibration Spectrum at 25 mph ...................................... 50

Figure 12: Typical Outdoor and Indoor Noise Level ...................................................... 73

Figure 13: Typical Vibration Levels ............................................................................... 75

Figure 14: SLU Streetcar Force Density measurement Location .................................. 77

Figure 15: LSTM and Coherence, Seattle South Lake Union Park ............................... 78

Figure 16: Measured Train Vibration at 25 feet from NT ............................................... 79


Noise and Vibration Technical Report Page iv May 2015 Environmental Assessment Tempe Streetcar


Figure 19: Measured Train Vibration at 100 feet from NT ............................................. 82

Figure 20: Measured Train Vibration at 125 feet from NT ............................................. 83

Figure 21: Average Seattle Streetcar Vibration ............................................................. 84

Figure 22: Average SLU Streetcar Force Density Levels .............................................. 85

Figure 23: SLU Streetcar Force Density Level .............................................................. 86

Figure 24: SLU Streetcar FDL for Predictions ............................................................... 86

Figure 25: Map of Portland Streetcar FDL Sites A, B and C ......................................... 89

Figure 26: Portland Streetcar Force Density Measurement Site C ................................ 90

Figure 27: LSTM and Coherence, Portland Site C ........................................................ 90

Figure 28: Measured Streetcar Vibration at Site C in Portland ...................................... 91

Figure 29: Portland Streetcar FDL at Site C (2011) ...................................................... 91

Figure 30: Comparison of Portland Streetcar FDL ........................................................ 92

Figure 31: Rail Roughness Measurements in Portland FDL Site C ............................... 94

Figure 32: Rail Condition in Portland ............................................................................. 94

Figure 33: Rail Roughness Measurement Results ........................................................ 94

Figure 34: Measured Streetcar FDL .............................................................................. 96

Figure 35: Measured Streetcar Noise Level at Portland Site C ..................................... 98

Figure 36: Vibration Propagation Site V-3 ................................................................... 100



Figure 39: First Floor Indoor Sensor at Site V-5 .......................................................... 101

Figure 40: Second Floor Indoor Sensor at Site V-5 ..................................................... 102


Noise and Vibration Technical Report Page v May 2015 Environmental Assessment Tempe Streetcar

Figure 42: Vibration Propagation Site V-11 ................................................................. 103



Figure 45: Vibration Propagation Site V-13, Indoor Sensors ....................................... 105


Figure 47: Vibration Propagation Site V-14, Indoor Sensors ....................................... 107

Figure 48: Aerial View of Vibration Propagation Site V-3 ............................................ 108




Figure 52: Aerial View of Vibration Propagation Site V-11 .......................................... 110




Figure 56: Measured LSTM and Coherence at Site V-3 .............................................. 113




Figure 60: Measured LSTM and Coherence at Site V-11 ............................................ 117




Figure 64: N11 24-hr ambient Noise Time History ...................................................... 126

Figure 65: N12 1-hr ambient Noise Time History ........................................................ 127

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Figure 67: N14 1/2-hr ambient Noise Time History ..................................................... 129








Figure 75: Alignment with Areas Labeled (1-4) ........................................................... 137

Figure 76: Alignment with Sensitive Receivers and Test Sites .................................... 138

Figure 77: Area 1 Sensitive Receivers ........................................................................ 139



Figure 80: Area 4 (Mill Ave) Sensitive Receivers ........................................................ 142

Figure 81: Area 4 (Gammage Curve) Sensitive Receivers .......................................... 143

Figure 82: Area 4 (Apache Blvd) Sensitive Receivers ................................................. 144

Noise and Vibration Technical Report Page vii May 2015 Environmental Assessment Tempe Streetcar

1.0 INTRODUCTION

1.1 BACKGROUND

This Noise and Vibration technical report is being prepared to support the Environmental Assessment (EA) for the proposed Tempe Streetcar project in Tempe, Arizona. The proposed project, or Build Alternative, connects the emerging commercial district of Rio Salado Parkway along the Tempe Town Lake front with the traditional downtown core of Tempe and the Mill Avenue District. South of University Drive and downtown Tempe, the alignment continues on Mill Avenue and wraps around the southern portion of ASU’s campus along Apache Boulevard terminating near the current Dorsey/Apache Blvd LRT Station. In total, the Build Alternative consists of a 3.0-mile modern streetcar line.

Described from north to south, the streetcar would operate bi-directionally on Rio Salado Parkway between the new Marina Heights development and the intersection of Mill Avenue and Rio Salado Parkway. The streetcar would then loop around downtown Tempe generally operating in a one-way couplet southbound on Ash Avenue and northbound on Mill Avenue. Specifically, the streetcar would traverse a one-way, counter-clockwise loop west on Rio Salado Parkway, south on Ash Avenue, and east on University Drive. During some special events in downtown Tempe the streetcar would complete the counter-clockwise loop by turning north on Mill Avenue at University Drive and continue to Rio Salado Parkway. However, during normal operations, where the trains on eastbound University Drive intersect with Mill Avenue, they would turn south and travel bi-directionally on Mill Avenue to 11th Street near ASU’s Gammage Auditorium. The bi-directional trackway would then follow the roadway curve around the southwest perimeter of Gammage Auditorium, turning onto Apache Boulevard and continuing in an east-west direction, eventually terminating near the current Dorsey/Apache Blvd LRT Station. The Build Alternative is shown in Figure 1.

The existing number of traffic lanes would be maintained with two exceptions: 1) the short segment along Mill Avenue between University Drive and 11th Street. In that segment, the existing three southbound through lanes would be reduced to two lanes, and a southbound bicycle lane would be added. An additional northbound through lane would be added to provide a total of two northbound through lanes and a bicycle lane. At 10th Street, the left-turn lane would be removed; and 2) Ash Avenue southbound between Rio Salado Parkway and University Drive. In that segment, the existing two southbound through lanes would be reduced to one lane, and the southbound bicycle lane would be moved adjacent to the remaining southbound through lane.

Noise and Vibration Technical Report Page 1 May 2015 Environmental Assessment Tempe Streetcar

FIGURE 1: BUILD ALTERNATIVE

Source: Valley Metro, May 2015.

The proposed streetcar system would operate with a single car and would generally share the existing auto travel lanes, thus minimizing the need to widen the current street rights-of-way (ROW). The project intends to use modern streetcar vehicles, powered by an overhead catenary system. Although a specific vehicle has not been selected, streetcar vehicle lengths typically range for 65 to 80 feet, with passenger capacities of 125 to 150 persons. While the exact type of rail vehicle has not yet been determined, it is anticipated it will have a minimum of two articulations (movable joints within the vehicle) to maneuver tight turns required for in-street operations. A portion of the vehicle will have a low floor to accommodate level boarding from platforms. The vehicle will either have adjustable suspension or bridge plates to accommodate Americans with Disabilities Act (ADA) requirements for vehicle/platform interface. The primary features of the Build Alternative are described in Table 1.


TABLE 1: TEMPE STREETCAR AT-A-GLANCE From – To: Rio Salado Parkway (between the Marina Heights development and

intersection of Mill Avenue and Rio Salado Parkway) – This segment has a double-track configuration. Downtown Tempe (between University Drive and Rio Salado Parkway) – This segment includes a single track, one-way counter-clockwise loop west on Rio Salado Parkway, south on Ash Avenue, and east on University Drive to Mill Avenue. Northbound trains will operate on a single track, one-way alignment north on Mill Avenue. Mill Avenue (south of University Drive to Apache Boulevard) and Apache Boulevard (east of Mill Avenue to Dorsey Lane) – This segment contains a double-track configuration, with the exception of a single track east of Terrace Rd.

Distance 3.0 route miles Number of streetcar stops

14 total stops

Traffic lanes

Shares travel lanes with autos and generally maintains existing numbers of traffic lanes with 2 exceptions: 1) Between University Drive and 11th Street where existing 3 southbound lanes would be reduced to 2 and a bike lane added. Existing 1 northbound lane would be increased to 2 lanes and existing bike lane remains; and 2) Southbound Ash Avenue where 2 southbound lanes are reduced to 1 lane.

Operations begin 2018 Headways Weekdays: 10-minute frequency in each direction most of the day. 20-minute

frequency in each direction in early mornings (5-6 a.m.) and late evenings (7 p.m. and later).

Vehicle capacity Carrying capacity of 125-150 passengers depending on vehicle and seating configuration.

Hours of operation Sunday through Thursday 19 hours (5 a.m. to 12 a.m.) Friday and Saturday 22 hours (5 a.m. to 3 a.m.)

Estimated operational speed

25 mph

Number of vehicles

6 – Includes revenue service vehicles and spares

Operations and maintenance

Uses existing Valley Metro Operations and Maintenance Center (OMC)

Source: Valley Metro, November 2014 and April 2015.


The proposed project’s vehicles will use the current Operations and Maintenance Center (OMC) now used to maintain and store light rail vehicles for the Valley Metro light rail system. The vehicles would use the existing LRT tracks to access the OMC. A total of 14 streetcar stops would be distributed throughout the 3.0-mile corridor as shown in Table 2.

With few exceptions, the streetcar trackway, stops, and lane configurations would remain within the existing public ROW footprint; however ROW would be necessary for traction power substations (TPSS) and signal buildings. The TPSSs would be spaced approximately one-mile apart from one another to provide electrical power for streetcar vehicles and special trackwork. The TPSS facilities convert electrical current to an appropriate type (AC to DC) and level to power streetcar vehicles. The candidate locations for eight TPSSs are listed in Table 3. Each location, with a land need (including setbacks and access drives) of approximately 70 feet by 100 feet, was sited to minimize impacts to the surrounding properties. The project would likely require fewer than eight TPSSs; however, all eight potential sites are in included in the analysis.

TABLE 2: STOP LOCATION BY TYPE Location Platform Type Orientation of Stop

on Street Marina Heights/Rio Salado Pkwy Center platform Center of Street Hayden Ferry/Rio Salado Pkwy Center platform Center of Street Tempe Beach Park/Rio Salado Pkwy Center platform Center of Street 3rd St/Ash Ave Side platform on curbside lane Southbound 5th St/Ash Ave Side platform on curbside lane Southbound University Dr/Ash Ave Side platform on curbside lane Southbound 6th St/Mill Ave Side platform on curbside lane Northbound 3rd St/Mill Ave Side platform on curbside lane Northbound 9th St/Mill Ave Center platform Center of Street 11th St/Mill Ave Center platform Center of Street College Ave/Apache Blvd Center platform Center of Street McAllister Ave/Apache Blvd Center platform Center of Street Rural Rd/Apache Blvd Center platform Center of Street

Dorsey/Apache Blvd Side platform adjacent to inner roadway lane Center of Street

Source: Tempe Streetcar drawings, Valley Metro, November 13, 2014 and April 2015.

TABLE 3: TRACTION POWER SUBSTATIONS LOCATION OPTIONS Abbreviation1 Drawing

Sheet No.1 Location

RS/P Option 1 3 Rio Salado Pkwy-Option 1 RS/P Option 2 2 Rio Salado Pkwy-Option 2 RS/A 4 Rio Salado Pkwy/Ash Ave


3/A 5 3rd St/Ash Ave 3/M 5 3rd St/Mill Ave U/M 7 University Dr/Mill Ave 13/M 9 13th St/Mill Ave A/T 2 Apache Blvd/Terrace Rd

1As shown in the separate package of drawings dated November 13, 2014, Valley Metro.


2.0 SUMMARY The analysis of potential noise and vibration impacts associated with the proposed project follows the FTA guidelines outlined in the FTA Guidance Manual (Ref. 1). This Technical Report documents the findings of the noise and vibration impacts associated with the project. In addition, the document includes the following Appendices:

• Appendix A: Fundamentals of Noise and Vibration • Appendix B: Force Density Measurement Results • Appendix C: Streetcar Noise Measurement Results • Appendix D: Vibration Propagation Test Results • Appendix E: Ambient Noise Measurement Sites • Appendix F: Sensitive Receiver Inventory

2.1 NOISE ASSESSMENT APPROACH

The detailed assessment for noise included the following steps:

1. Identify sensitive receivers. Noise-sensitive land uses along the corridor were identified first using aerial photography. Field visits were then conducted to confirm land uses and gather additional relevant information, such as the presence of second stories, land use in the first floor of mixed use buildings (for example first floor shops and restaurants at the Brickyard Engineering building), and the presence of any intervening structures. Sensitive receivers were grouped together in clusters, where appropriate, based on their location relative to the tracks and land use type. Predictions for each cluster are based on the distance from the proposed project to the closest sensitive receiver. Appendix F (Sensitive Receiver Inventory) details the cluster locations used in the assessment.

2. Determine existing conditions. As discussed in Section 4.0 and Appendix E (Ambient Noise Measurement Sites), existing noise levels were measured along the project corridor at five long-term sites for 24 hours, and at six short-term sites for 1+ hours. The measurements were used to estimate the existing Ldn and daytime Leq at all of the sensitive receiver clusters.

3. Develop prediction models. The noise prediction models are based on formulas provided in the FTA Guidance Manual and noise measurements of the Phoenix Metro (LRT) Starter Line. The predictions of streetcar noise are based on the forecasted future number of daily streetcars and the distribution of these streetcars throughout the day (early morning, daytime, and nighttime), the distance from the tracks, the streetcar speed, the presence of walls, berms, or other structures that


reduce noise levels, and other site-specific conditions. For receivers located within 100 feet of the streetcar stops the predictions of passby noise includes the streetcar bell. A Model was also developed to predict noise from traction power substation (TPSS) units.

4. Estimate future noise levels at the representative receivers. The prediction models were used to predict noise levels from streetcar operations at all clusters of sensitive receivers in the Tempe Streetcar corridor. The predictions were compared to the applicable FTA impact thresholds to identify potential noise impacts (see Section 7.1).

5. Evaluate mitigation options. Mitigation options were evaluated for all locations where the predicted noise levels exceed the FTA impact thresholds (see Section 7.4).

2.2 VIBRATION ASSESSMENT APPROACH

The detailed assessments for vibration included the following steps:

1. Identify sensitive receivers. Vibration-sensitive land uses along the corridor were identified using the same procedure as the noise analysis. Sensitive receivers were grouped together in clusters based on their location relative to the tracks and land use type. The residential land use clusters were the same for both noise and vibration assessments. Predictions for each cluster are based on the distance from the proposed project to the closest sensitive receiver. Appendix F details the cluster locations used in the assessment. The noise-sensitive institutional land uses are also vibration-sensitive with the exception of open spaces such as parks that are not considered vibration-sensitive land uses. In addition, recording studios and theaters and concert halls that are considered as highly sensitive land uses for noise are considered as “special buildings” for vibration impact evaluation.

2. Develop prediction models. The vibration prediction models are based on the force density level (FDL) measurements from the Portland and Seattle Modern Streetcar systems (performed by ATS in June 2006 and July 2011) and vibration propagation tests at representative sites along the Tempe Streetcar corridor spaced approximately a half-mile apart or less. The vibration prediction models are based on the FTA guidance manual’s detailed vibration assessment methodology.

3. Estimate future vibration levels at the representative receivers. The prediction models were used to predict vibration levels from streetcar operations at all sensitive receivers in the Tempe Streetcar corridor. The predictions were compared to the


applicable FTA impact thresholds to identify potential vibration impacts (see Section 7.3).

4. Evaluate mitigation options. Mitigation options were evaluated for all locations where the predicted vibration levels exceed the FTA impact thresholds (see Sections 7.5).

2.3 NOISE CONCERNS ASSOCIATED WITH THE STREETCAR SYSTEM

The following list summarizes most of the major noise sources associated with operating streetcar systems. See Section 6.0 for more details.

Streetcar Operations: This is the normal noise from the operation of streetcars and includes noise from steel wheels rolling on steel rails (wheel/rail noise) and from propulsion motors, air conditioning, and other auxiliary equipment on the vehicles. At the time of this study the maximum operating speed considered for the streetcar is 25 mph. A key assumption in the noise predictions is that the optimal wheel and rail profiles would be maintained for the Tempe Streetcar system through periodic truing of the wheels and rail grinding.

Traffic Noise: The streetcar shares the right-of-way with vehicular traffic, and the proposed project would result in minimal changes in traffic patterns and volumes in the project area. Therefore only minimal changes in sound levels may be expected from these potential changes. There are no proposed property acquisitions for the project that would require demolishing any current buildings between the roadway and sensitive receivers, and the existing acoustic shielding would not be altered for any noise-sensitive receivers. Therefore, a detailed assessment of impacts from traffic noise is not a part of this study, however, a brief traffic noise analysis was conducted for one area of the alignment where a new roadway lane is being added.

Audible Warnings: The streetcars will be equipped with horns and bells as audible warning devices. The horns will be used in the same manner as on the buses along the alignment to alert pedestrians and motor vehicles of a potential safety risk. The horns are not expected to be used frequently enough to have any effect on the noise exposure. Therefore horn noise has not been included in the noise analysis. Because the bells would be used on a regular basis at stops, bell noise was included in the analysis for all noise-sensitive receivers located within 100 feet of the stops (streetcar stops and stoplights).

Special Trackwork: The Tempe Streetcar corridor will be constructed of continuously welded track, which eliminates the clickety-clack noise associated with older rail


systems. The one exception is the special trackwork for turnouts and crossovers, where two rails must cross. A fixture called a frog is used where rails must cross. The wheel impacts at the gaps in the rails of a standard frog cause noise levels near special trackwork to increase by approximately 6 dB. As is common on streetcar systems, the frogs are “flange bearing.” That is, there is a short ramp before and after the gap where the load is transferred from the wheel tread to the wheel flange. However, the ramps on typical streetcar flange-bearing frogs are short enough that the transfer of the load is quite abrupt and generates substantial noise. Therefore use of well-designed flange-bearing frogs with longer ramps that have a more gradual transfer of the load from the tread to the flange can substantially reduce the impacts that cause high noise and vibration from special trackwork. A “well-designed” flange-bearing frog requires a minimum ramp length of two feet. In addition to a flange-bearing frog, another low-impact version is a monoblock frog. A monoblock frog is machined out of a single block of steel with tight tolerances. Flange-bearing frogs and monoblock frogs each reduce the noise by about half compared to ones that are not low-impact.

Wheel Squeal: Wheel squeal is generated when steel-wheel transit vehicles traverse tight radius curves. It is very difficult to predict when and where wheel squeal will occur. A general guideline is that there is the potential for wheel squeal at any curve with a radius that is less than approximately 600 feet. There is the potential for the Tempe streetcars to generate wheel squeal on the sharper curves along the alignment. Common approaches to controlling wheel squeal include (1) applying a friction modifier to the railhead and/or the wheel tread, (2) applying lubricant to the gauge face of the rail or the wheel flange, and (3) optimizing the wheel and rail profiles. Using resilient wheels and maintaining the tracks will help control wheel squeal; also, periodically truing wheels will maintain an optimum profile and can help minimize wheel squeal.

Ancillary Equipment: The only ancillary equipment associated with the proposed project with potential for creating noise impact are the traction power substations (TPSS). Although fewer TPSS locations are required for the streetcar system, eight potential locations have been identified. A general guideline is that locating the TPSS at least 50 feet from the closest residential land use will avoid noise impacts.

Construction: All the sources discussed above are associated with the operation of the proposed project. Although construction of a streetcar project entails relatively less use of heavy equipment compared to other rail projects, construction activities nevertheless would generate relatively high noise levels. Potential construction noise impacts are assessed separately from operational noise impacts.


2.4 VIBRATION CONCERNS ASSOCIATED WITH THE STREETCAR SYSTEM

The following list summarizes most of the significant vibration sources associated with operating streetcar systems. See Section 6.2 for more details.

Streetcar Operations: Streetcar operations create groundborne vibration that can be intrusive to occupants of buildings that are located close to the tracks. This is particularly important for residential land uses that are located within 50 ft of streetcars operating at 25 mph. The predicted levels of streetcar vibration at all receivers are well below the thresholds used to protect sensitive and fragile historic structures from damage. The potential for vibration from streetcar operations to be annoying to occupants of historic structures is based on the appropriate vibration impact criteria for the current use of the building. The predicted groundborne noise and vibration from the streetcar would not exceed the FTA impact criteria at any of the "special buildings" along the corridor. A key assumption in the vibration predictions is that the optimal wheel and rail profiles would be maintained for the Tempe Streetcar system through periodic truing of the wheels and rail grinding.

Special Trackwork: Turnouts and crossovers, where two rails cross, are the primary source of special trackwork on the alignment. This type of special trackwork, where two rails cross, is sometimes referred to as a “frog.” Standard frogs have gaps, and the train wheels must “jump” across the gap. The wheels striking the ends of the gap increase vibration levels as well as noise levels. The groundborne vibration levels near special trackwork increase by approximately 10 dB due to the wheel impacts at the gaps in the rails. The ramps on typical streetcar flange-bearing frogs are short enough that the transfer of the load is quite abrupt and generates substantial vibration in addition to noise. Use of well-designed flange-bearing frogs with longer ramps can substantially reduce the impacts that cause high vibration from special trackwork. The “well-designed” flange-bearing frog with a minimum ramp length of two feet would be sufficient to reduce vibration. In addition to a flange-bearing frog, another low-impact version is a monoblock frog. A monoblock frog is machined out of a single block of steel with tight tolerances. Flange-bearing frogs and monoblock frogs each reduce the vibration by about half compared to ones that are not low-impact.

Construction: Construction of a streetcar project entails relatively less use of heavy equipment compared to other rail projects. Nevertheless, the construction activities of the project would generate perceptible vibration levels. Potential construction vibration impacts are assessed separately from operational vibration impacts.


2.5 SUMMARY OF NOISE IMPACT ANALYSIS

This section summarizes the results of the noise impact assessment for the Tempe Streetcar project. The predicted noise levels for streetcar operations includes the noise from the steel wheels of the streetcar rolling on the steel rails and the noise from bells as the streetcar arrives and departs from stops or passes through an intersection. The impact analysis does not include noise from warning horns because they will only be used in case of emergency. Noise levels from traction power substation (TPSS) units were assessed separately at noise-sensitive receivers located closest to the sites. The TPSS units are the only ancillary noise source associated with the project.

The noise-sensitive receivers where impact is predicted are presented in Table 4. The FTA guidance manual provides two levels of noise impact: moderate and severe. Below is a summary of the predicted impacts:

• Predicted noise from streetcar operations does not exceed the applicable FTA noise impact threshold at any Category 1 (highly sensitive) land uses.

• Predicted noise from streetcar operations exceeds the applicable FTA moderate noise impact threshold by 1 dB or less at five single-family residences, a hotel, and an ASU residence hall. These receivers are Category 2 (residential) land uses. All of the receivers where impact is predicted are located near the curve as the tracks transition from Mill Avenue onto Apache Boulevard. Predicted streetcar noise levels are higher at sensitive receivers located near a curve because wheel squeal often occurs on curves and can increase noise levels by as much as 10 decibels.

• Predicted noise from streetcar operations does not exceed the applicable FTA noise impact threshold at any Category 3 (institutional) land uses. Category 3 land uses include schools, churches, most parks and other institutional land uses with daytime sensitivity.

• Predicted noise levels at a cluster of noise sensitive receivers (four single-family residences) near one TPSS site exceed the applicable noise impact threshold. The TPSS site (designated as the TPSS U/M Option in the Environmental Assessment conceptual engineering drawings) is located within 50 feet of the facade of the nearest residences on Maple Avenue between University Drive and 9th Street.

To mitigate the predicted noise impacts from streetcar operations, friction control would be included in the design to help reduce the occurrence of wheel squeal on the curve connecting the Mill Ave section to the Apache Blvd section. Friction control may consist of installing lubricators on the rail or using an onboard lubrication system that applies lubrication directly to the wheel. Including friction control in the design would reduce the


predicted noise levels to below the FTA moderate noise impact threshold at all noise-sensitive receivers.

To mitigate the predicted noise impact from the TPSS unit, the TPSS unit would be strategically within the site, with the major noise source, the cooling fans, being as far from the residences as possible. If the TPSS unit is located within the parcel as far as feasible and oriented with the cooling fans facing away from the sensitive receivers, the predicted noise level could be reduced to below the applicable threshold. The cooling fans on the TPSS unit should be facing toward Mill Avenue and located more than 50 feet from the nearest residence to reduce the predicted noise levels to below the impact threshold. If there is not much flexibility on where to locate the unit within the parcel, a sound enclosure would be built around the TPSS unit to reduce noise levels at the sensitive receivers.

Noise mitigation measures should be reviewed and finalized in the final design phase of the project.


TABLE 4: SUMMARY OF PREDICTED NOISE IMPACTS AND MITIGATION FOR

STREETCAR OPERATIONS FTA

Category of Land

Uses

ID Description Exceed FTA Impact Threshold

# of Impacted

Units

Amount Exceeds

Threshold

Mitigation Option

Moderate Severe

Category 1 -- -- -- -- 0 -- --

Category 2

R8 SFR Yes No 1 <1 dB

Friction control for curve

R11 SFR Yes No 1 1 dB R12 SFR Yes No 1 <1 dB R13 SFR Yes No 1 <1 dB R19 SFR Yes No 1 <1 dB R20 Hotel Yes No 72 <1 dB

R21 ASU Residence Hall Yes No 45 1 dB

R35 SFRs Yes1 No 4 <1 dB Noise control at TPSS unit

Category 3 -- -- -- -- 0 -- -- Notes: SFR = Single-family residential, MFR = Multi-family residential. ID identifies a receiver as shown in the maps in Appendix F. 1. Predicted noise level equals the TPSS noise impact threshold (considered an impact). The FTA impact thresholds used to assess impact from train noise is not used to assess impact from TPSS noise.

2.6 SUMMARY OF VIBRATION IMPACT ANALYSIS

This section summarizes the results of the vibration impact assessment for the Tempe Streetcar project. The vibration-sensitive receivers where impact is predicted are presented in Table 5. Below is a summary of the predicted impacts:

• There are no FTA Category 1 (highly sensitive) land uses for groundborne vibration along the Tempe Streetcar corridor.

• Groundborne vibration from streetcar operations is predicted to exceed the FTA impact threshold at two Category 2 (residential) land uses, where there is sensitivity to nighttime noise. The receivers where vibration impact is predicted are located near special trackwork where two rails cross, and typical frogs cause vibration to increase 10 dB. For the special trackwork that would be located on Mill Avenue between 9th and 10th Streets, one multi-family residence and five units at a nearby hotel would be adversely affected without mitigation.


• Predicted vibration levels are below the FTA impact threshold for all Category 3 (institutional) land uses.

• The FTA guidance manual identifies “special buildings” for vibration impact evaluation that fall outside of the land use Categories 1, 2, and 3. These buildings include theaters, auditoriums, recording studios, TV studios, and concert halls. The “special buildings” identified in the project area include the Valley Art Theater, the Gammage Auditorium, and the ASU Music Building. Predicted vibration levels are below the FTA impact thresholds at all of the “special buildings”. Note: For the Valley Art Theater, predictions do not include the building response as the vibration propagates from the façade to the screening room (could not gain access to do related measurements); indoor measurements during final design could clarify whether or not the building response would change the predicted vibration levels.

To mitigate for operational vibration, low-impact frogs would be installed at the special trackwork near vibration-sensitive receivers. Low-impact frogs can reduce vibration levels by creating a smoother transition through the gap in the rails at the special trackwork. Examples of low-impact frogs include monoblock frogs or flange-bearing frogs. Installing low-impact frogs would reduce the predicted vibration levels to below the FTA impact threshold at all sensitive receivers. Vibration mitigation measures should be reviewed and finalized in the final design phase of the project.

Note that historic structures that do not fall into the FTA land use categories are not included in the assessment for vibration impact from streetcar operations. The vibration impact thresholds are based on annoyance, and the primary concern for historic structures is the risk of damage. The recommended limit in the FTA guidance manual for buildings extremely susceptible to damage is 90 VdB, which is 18 decibels higher than the limit for Category 2 (residential) land uses. Vibration from streetcar operations will be well below the limit for buildings extremely susceptible to damage at all historic resources.


TABLE 5: SUMMARY OF PREDICTED VIBRATION IMPACTS AND APPLICABLE MITIGATION

FTA Category of Land Uses

ID Description Amount Exceeds FTA

Impact Threshold

# of Impacted Units Without

Mitigation

Mitigation

Category 1 -- -- -- -- --

Category 2 R6 Motel 5 3 Low-impact frogs for special

trackwork on Mill Avenue between 9th Street and 10th

Street R7 SFR 1 1

Category 3 -- -- -- -- --

Special Buildings -- -- -- -- --

Notes: SFR = Single-family residential, MFR = Multi-family residential. ID identifies sensitive receivers as shown in the maps in Appendix F.

2.7 SUMMARY OF CONSTRUCTION NOISE AND VIBRATION IMPACT ANALYSIS

2.7.1 Construction Noise Construction noise levels depend on the number of pieces and type of equipment, their general condition, the amount of time each piece operates per day, and the location of the construction equipment relative to the sensitive receivers. The majority of these variables are left to the contractor. Therefore, it is only possible to roughly estimate construction noise levels at this stage of the project.

Construction noise levels were predicted using estimates of the types of equipment likely to be used during the noisiest periods of track construction. The predicted construction noise level exceeds the FTA impact threshold for construction noise by 4 decibels at 50 feet. Given that there are many residences in the project area that are within 50 feet of the alignment, construction noise impacts are likely unless the contractor is required to implement noise control measures when working near residences.

Listed below are some typical approaches to reducing noise levels associated with the construction phase of major projects. Requiring the contractor to employ these methods should leave the contractor with enough flexibility to perform the work without undue financial or logistical burdens while protecting adjacent noise sensitive receivers from excessive construction noise levels.

• Avoid nighttime construction unless a variance is issued by the City. This is a requirement of the City of Tempe noise ordinance.


• Use specialty equipment with enclosed engines and/or high-performance mufflers.

• Locate equipment and staging areas as far from noise-sensitive receivers as possible.

• Limit unnecessary idling of equipment.

• Install temporary noise barriers. This approach can be particularly effective for stationary noise sources such as compressors and generators.

• Reroute construction related truck traffic away from local residential streets. Specific measures to be employed to mitigate construction noise impacts should be developed by the contractor and presented in the form of a Noise Control Plan.

2.7.2 Construction Vibration The primary concern regarding construction vibration is potential damage to structures. The thresholds for potential damage are much higher than the thresholds for evaluating potential annoyance used to assess impact from operational vibration. At a distance of 50 feet from buildings, the predicted vibration levels from construction are below the damage risk criteria for even those buildings most sensitive to damage. At a distance of 25 feet, the vibration level from high vibration generating equipment, such as a vibratory roller, is predicted to exceed the impact threshold for timber and masonry buildings, and those buildings most susceptible to damage.

It is unlikely that high vibration generating equipment, such as a vibratory roller, will be operated closer than 25 feet of the nearest buildings. However, the following precautionary vibration mitigation strategies would be implemented to minimize the potential for damage to any structures in the corridor:

1. Pre-Construction Survey: The survey should include inspection of building foundations and taking photographs of pre-existing conditions. The survey can be limited to buildings within 25 feet of high-vibration generating construction activities. The only exception is if an important and potentially fragile historic resource is located within approximately 200 feet of construction, in which case it should be included in the survey.

2. Vibration Limits: The FTA guidance manual suggests vibration limits in terms of peak particle velocity (PPV) ranging from 0.12 in/sec for “buildings extremely susceptible to vibration damage” to 0.5 in/sec for “Reinforced-concrete, steel or timber” buildings. The contract specifications should limit construction vibration to a maximum of 0.5 in/sec for all buildings in the corridor. Should the pre-construction survey identify any buildings that are particularly sensitive to vibration, such as the Hayden House (most recently known as Monti’s La Casa Vieja), the vibration at these structures should be limited to 0.12 in/sec.


3. Vibration Monitoring: The contractor should be required to monitor vibration at any buildings where vibratory rollers or similar high vibration-generating equipment would be operated within 25 feet of buildings and at any location where complaints about vibration are received from building occupants.

4. Alternative Construction Procedures: If high-vibration construction activities would be performed close to structures, it may be necessary for the contractor to use an alternative procedure that produces lower vibration levels. Examples of high-vibration construction activities include the use of vibratory compaction or hoe rams next to sensitive buildings. Alternative procedures include use of non-vibratory compaction in limited areas and a concrete saw in place of a hoe ram to breakup pavement.

An historic adobe structure, the Hayden House, is located at the corner of Rio Salado Parkway and Mill Avenue, about 50 feet from the proposed streetcar tracks. As discussed above, predicted vibration levels from construction equipment do not exceed the construction vibration limit for buildings extremely susceptible to damage at 50 feet. No adverse effect from construction vibration is predicted for the Hayden House. Although no adverse effect is predicted, the Hayden House would be included as part of the Pre-Construction Survey to document existing conditions.


3.0 INVENTORY OF NOISE- AND VIBRATION-SENSITIVE SITES Noise and vibration sensitive receivers were identified using the FTA guidance manual’s definitions of noise and vibration sensitive land uses. Existing noise-sensitive receivers in the Tempe Streetcar corridor consist of many single- and multi-family residences, hotels, schools, religious and cultural churches or institutions, parks, post office, ASU academic buildings, Gammage Auditorium and the Valley Art Theater. A full list of sensitive receivers can be found in Appendix F; the list includes those potentially sensitive to streetcar noise and vibration, as well as those potentially sensitive to the TPSSs. The parks, which are outdoor land uses, are not sensitive to vibration. All other receivers which are indoor land uses are sensitive to vibration. The indoor land uses consist of 739 existing dwelling units plus units in Lennar Development near the alignment, 13 institutional land uses, and three special buildings (theaters and concert halls, considered highly sensitive land uses). In addition, the Hayden House, an historic adobe structure, was assessed for the potential for damage from vibration.

4.0 AFFECTED ENVIRONMENT A noise and vibration test and measurement program was developed to characterize the ambient noise and vibration in the project area. The tests were conducted in two phases: Phase 1 of the test program included vibration propagation tests at six sites and ambient vibration measurements that included train and bus passby measurements. These tests were conducted by ATS between May 16 and 19, 2011. At the vibration propagation test sites, the ambient vibration was measured to verify if the background vibration was below the test signals. These vibration propagation measurements are documented in Appendix D.

Phase 2 of the test program was performed between December 8 and 12, 2014, before winter break at ASU. This second test program was conducted for two reasons: 1) to characterize the current noise environment throughout the alignment, and 2) to characterize ambient vibration and vibration propagation at sites not previously tested. This set of measurements included vibration propagation tests at four sites, and 11 noise measurements (both long and short term). The Phase 2 measurements are documented in Appendix D and Appendix E.

To distinguish the measurements by date, the sites have been designated numerically: numbers below 10 designate measurements from Phase 1 (those performed in 2011), while numbers above 10 designate measurements from Phase 2 (those performed in 2014).

A map of the noise and vibration test sites are shown in Figure 2, and the details of the measurements are discussed in the rest of this section. Noise and Vibration Technical Report Page 18 May 2015 Environmental Assessment Tempe Streetcar

FIGURE 2: MAP OF NOISE AND VIBRATION TEST SITES

*Special land uses include the following: Valley Arts Theater, ASU New Music Building, and Gammage Auditorium. These fall into different categories for noise and vibration due to the sensitivities to each. Also shown as a special land use is the historic structure Hayden House (Monti's La Casa Vieja), evaluated only for construction vibration.

4.1 EXISTING CONDITIONS - NOISE

The FTA noise impact analysis is based on the existing ambient noise in the project area. The Tempe Streetcar project area has several transportation-related noise sources including vehicular traffic, light rail, freight rail, and airplane noise as listed below:

• The primary source of traffic noise is vehicles on Mill Avenue, Ash Avenue, Rio Salado Parkway, and Apache Boulevard, including major intersections.

• Freight train noise on Ash Avenue involves train passby noise and the horn noise near the grade crossings at 1st Street, 5th Street and University Drive.


• Light rail is a major noise source on 3rd Street. It includes the use of bells at the traffic light on Ash Avenue and when the trains approach and leave the 3rd Street LRT Station near Mill Avenue.

• Airplanes are a major noise source north of 5th Street because this area is below the flight path for arrival traffic to runways 25L and 25R at Phoenix Sky Harbor International Airport.

The existing ambient noise levels along the project corridor were documented through a series of noise measurements performed at a number of representative sensitive receivers. In 2014, noise measurements were performed by ATS at five long-term sites for a period of 24 hours and at six short-term sites for durations ranging from 30 minutes to 1 hour. The results of the measurements are summarized in Table 6, and more detailed measurement information is included in Appendix E.

The next few paragraphs give a brief overview of noise measurement terminology, while the details of noise fundamentals are discussed in Appendix A: Fundamentals of Noise and Vibration. A logarithmic scale, known as the decibel scale (dB), is used to quantify sound intensity and compress the scale to a more convenient range. To better approximate the sensitivity of human hearing, the A-weighted decibel scale has been developed and abbreviated as “dBA”. Some key metrics of sound are presented here and more details of sound fundamentals are presented in Appendix A.

Equivalent Sound Level (Leq): The equivalent sound level (Leq) is the most common means of characterizing community noise. Leq represents a constant sound that, over a specified period of time, has the same sound energy as the time-varying sound. In other words, it is a sound energy average over a specified period of time. Leq is used by FTA to evaluate noise impacts at institutional land uses, such as schools, churches, and libraries, from proposed transit projects.

Daytime Sound Level (Leq daytime): The daytime sound level (Leq day) is the Leq measured over a specified period of time during the day between the hours of 7:00 AM and 10:00 PM.

Nighttime Sound Level (Leq nighttime): The nighttime sound level (Leq night) is the Leq measured over a specified period of time during the night between the hours of 10:00 PM and 7:00 AM.

Day-Night Sound Level (Ldn): Ldn is basically a 24-hour Leq with an adjustment to reflect the greater sensitivity of most people to nighttime noise. The adjustment is a 10 dB penalty for all sound that occurs between the hours of 10:00 PM to 7:00 AM. The effect of the penalty is that, when calculating Ldn, any event that occurs during the nighttime is equivalent to ten occurrences of the same event during the daytime. Ldn is Noise and Vibration Technical Report Page 20 May 2015 Environmental Assessment Tempe Streetcar

the most common measure of total community noise over a 24-hour period and is used by FTA to evaluate residential noise impacts from proposed transit projects.

Maximum Sound Level (Lmax): Lmax is the maximum sound level that occurs during an event such as a train passing. For this analysis Lmax is defined as the maximum sound level using the slow setting on a standard sound level meter. In other words, the Lmax is the maximum one-second Leq during the measurement.

Sound Exposure Level (SEL): SEL is a measure of the acoustic energy of an event such as a train passing. In essence, the acoustic energy of the event is compressed into a 1-second period. SEL increases as the sound level of the event increases and as the duration of the event increases. It is often used as an intermediate value in calculating overall metrics such as Leq and Ldn.

The locations of the measurement sites are provided in Figure 2. Site labels for noise are designated in green and their prefix varies based on the type of noise measurement it was. Sites labeled with “N” designate a noise measurement site measured in 2014 and can be either long-term or short-term measurement sites. The results of the noise measurements are summarized in Table 6. Since the FTA impact criteria for receivers where a quiet nighttime noise environment is required (i.e. hotels and residences) uses Ldn, the noise metric presented is Ldn for residential receivers and Leq otherwise (note that for sites with a 24-hour Ldn presented, a 24-hour Leq is also presented for informational purposes). The details of each measurement site follow.

N-11 Bridgeview Condos: This long-term noise measurement was performed on the southwest terrace of the Bridgeview Condos at the same level as “first floor” residences. The microphone was 50 feet from the near lane of Rio Salado Pkwy which was the primary noise source during the measurement. The secondary noise source was airplanes. The chosen location was in line with the building façade facing the road and about 15 feet from the closest outdoor use on the property. The measured 24-hour Ldn was 68 dBA.

N-12 Tempe Beach Park: This short-term noise measurement was performed on top of a hill on the south end of the Tempe Beach Park. The distance to the near lane of Rio Salado Parkway was 70 feet. Primary noise sources were vehicular traffic on Rio Salado Pwky and airplanes. There was pedestrian use of the park at a minimum distance of 50 feet, but vehicular and airplane noise sources dominated the measurement. The measured 1-hour Leq was 68 dBA.

N-13 Hayden Square Condos: This long-term measurement was performed at the Hayden Square Condominiums on 3rd Street on the side closest to the future alignment. It was intended to update the noise levels from the previous recordings made


at this site in 2011. Unfortunately, a complete comparison could not be made since eight hours of the 2014 measurement were not recorded due to an error in the noise monitor. However, by comparing to the previous measurements, we were able to interpolate an estimation of the missing data. The resulting Ldn was 70 dBA.

N-14 Courtyard Marriott: These short-term measurements were performed near the Courtyard Marriott on Ash Avenue. To avoid inflation of noise levels from construction nearby, the recording was started after work hours and lasted only 30-minutes. The primary noise source was vehicular traffic on Ash Avenue. The microphone was located at the corner of the hotel property closest to Ash Avenue. This recording included no construction noise and no freight train noise. The Leq for this 30-minute measurement was 66 dBA. Compared to the previous measurement at the same location, the levels are very similar. The noise at this site was found to be similar to that of the equivalent hour of site N13, so N13 was used to represent the receivers of the area.

N-15 Valley Art Theater: This short-term noise measurement was performed adjacent to the Valley Art Theater, in line with the theater façade. The microphone was 29 feet from the near lane of Mill Avenue. The primary noise source was vehicular traffic on Mill Ave and secondary noise sources were pedestrian foot traffic between the microphone and the street. The measured 1-hour Leq was 65 dBA.

N-16 941 S Mill: This long-term noise measurement was performed at the property edge of a parking lot on Mill Avenue (37 feet from the near lane of Mill Ave). The microphone was placed in the sparse tree line between the parking lot and the sidewalk next to Mill Avenue. The site was opposite the University Inn and another residential sensitive receiver along the alignment. Vehicular traffic on Mill Avenue was the primary noise source. The measured 24-hour Ldn was 69 dBA.

N-17 1104 S Mill: This short-term noise measurement was performed on the southwest corner of 11th St / Mill Ave near the residence at 1104 S Mill Avenue. The microphone was placed next to the 11th St sidewalk 41 feet from the near lane of Mill Avenue, which was also the setback distance of the property lines for residential sensitive receivers on that block of Mill Avenue. The primary noise source was vehicular traffic on Mill Avenue. The measured 1-hour Leq was 66 dBA. This site was originally planned to be a 24-hour measurement, but access to the property could not be attained so a short-term measurement was performed on the public sidewalk next to the residence.

N-18 Vista del Sol: This long-term noise measurement was performed near the Vista del Sol student housing tower K. The microphone was located in a planter between the building and the sidewalk, 47 feet from the near lane of Apache Blvd. The primary noise source was vehicular traffic on Apache Blvd. Secondary noise sources included


pedestrian foot traffic, gardening equipment, student security vehicles, and vehicles turning into the parking lot nearby. The measured 24-hour Ldn was 69 dBA.

N-19 Ten40 Church: This long-term noise measurement was performed at the property edge of the Ten40 Church closest to Apache Blvd. The microphone was 43 feet from the near traffic lane on an island between the sidewalk and the church parking. The measured Ldn was 69 dBA.

N-20 Sonoran Ridge Apartments: This short-term noise measurement was performed at the property edge of the Sonoran Ridge Apartments closest to the future alignment on Apache Blvd. The microphone was 47 feet from the near traffic lane above a 3 foot brick wall dividing the parking lot from the sidewalk. The measured 1-hour Leq was 63 dBA. It should be noted that this measurement location also represents the Lennar Development, which will replace the Sonoran Ridge Apartments.

N-21 1303 S Mill: This short-term noise measurement was performed on a grassy area between 13th Street and the residence at 1303 S Mill Avenue. The microphone was placed 105 feet from the near lane of Mill Avenue and 57 feet from the near lane of 13th Street. The primary noise source was the vehicular traffic from Mill Avenue, while the secondary noise source was vehicular traffic on 13th Street. The measured 1-hour Leq was 62 dBA. In order to predict the Ldn at nearby receivers, the data from this site was combined with that of site N-18 to estimate an equivalent Ldn. This was done by first comparing the measured hour to the equivalent hour at site N-18 and then applying that correction factor to the hourly data of N-18. When these estimated hourly levels were combined, the resultant Ldn was 70 dBA.


TABLE 6: SUMMARY OF EXISTING NOISE MEASUREMENTS

Site Location Date Dur.1 Start Time, hh:mm

Dist. from Near

Lane of Adjacent Street, ft2

Leq at 50 ft, dBA

Ldn at 50 ft, dBA

N-11 Bridgeview Condos 12/9/14 24-hr. 12:00 PM 50 66 68 N-12 Tempe Beach Park 12/11/14 1-hr. 1:33 PM 70 68 --

N-13 Hayden Square Condos 12/10/14 24-hr. 4:00 PM 135 675 705

N-14 Courtyard Marriott 12/10/14 1/2-hr. 3:58 PM 32 664 -- N-15 Valley Art Theater 12/10/14 1-hr. 10:05 AM 29 65 -- N-16 941 S Mill Ave 12/8/14 24-hr. 5:30 PM 37 65 69 N-17 1104 S Mill Ave 12/9/14 1-hr. 2:37 PM 41 66 -- N-18 Vista del Sol K 12/10/14 24-hr. 9:00 AM 47 65 69 N-19 Ten40 Church 12/9/14 24-hr. 4:00 PM 43 66 69

N-20 Sonoran Ridge Apartments 12/11/14 1-hr. 3:04 PM 47 63 --

N-21 13th St / Mill Ave 12/11/14 1-hr. 3:53 PM 105 66 706

Source: ATS Consulting (2014). 1 Duration of measurement. 2 The distance of the microphone from the centerline of nearest lane of Mill Avenue/Ash Avenue/3rd Street/Rio Salado Pkwy/Apache Blvd. Leq and Ldn levels shown have been normalized to 50 ft using the correction factor: +10*LOG10(Dist_from_Near_Lane/50).

3 Freight train passby noise excluded to create a more conservative lower existing noise level. 4 Excludes freight train passby noise and excludes construction noise 5

8 hours of data at this site failed to record due to equipment failure. These were replaced with interpolated data based on previous measurements.

6 The Ldn for this site was extrapolated using data from N-18.

4.2 EXISTING CONDITIONS – VIBRATION

The potential adverse effects of streetcar groundborne vibration include perceptible building vibration, rattle noises, reradiated noise (groundborne noise), and cosmetic or structural damage to buildings. Existing vibration sources in the project corridor primarily consist of vehicular traffic. Secondary sources include LRT and freight rail operations, and intermittent construction activities. When vehicular traffic causes perceptible vibration, the source usually is traced to potholes, wide expansion joints, or other “bumps” in the roadway surface.

The FTA assessment procedures for vibration from rail transit projects do not require measurements of existing vibration levels. The criteria for vibration impact are independent of existing vibration levels. Therefore, existing vibration levels were used only to internally validate the measurement data gathered from the vibration prediction model test sites in Section 6.2.


5.0 REGULATORY FRAMEWORK

5.1 STATE AND LOCAL NOISE AND VIBRATION LIMITS

There are no state statutes related to noise and vibration that apply to the operation of the proposed project. The FTA Noise and Vibration guidelines are used for this evaluation. The FTA guidelines, analysis methods, and criteria reflect the best available research on the topic. The City of Tempe Noise Ordinance places limits on construction noise, and these limits are discussed in Section 8.1 as part of the construction noise impact assessment.

5.2 FTA NOISE IMPACT CRITERIA

The noise impact criteria for use on federally financed transit projects are defined in the FTA Guidance Manual. The FTA criteria are based on the best available research on community response to noise. This research shows that characterizing the overall noise environment using measures of noise exposure provides the best correlation with human annoyance. Noise exposure characterizes noise levels over a period of time.

The FTA provides different thresholds for different land uses. Table 7 lists the three FTA land-use categories and the applicable noise metric for each category. For Category 2 land uses (residential areas where people sleep), noise exposure is characterized using Ldn. In calculating Ldn, noise generated during nighttime hours is more heavily weighted than daytime noise to reflect residents’ greater sensitivity to noise during those hours. For Category 1 and Category 3 land uses (areas with primarily daytime use), noise exposure is characterized using the peak hour Leq, which is a time-averaged sound level over the noisiest hour of transit related activity. Appendix A provides background information on the Ldn and Leq noise descriptors.


TABLE 7: FTA LAND USE CATEGORIES AND NOISE METRICS Land Use Category

Noise Metric (dBA)

Description of Land Use Category

1 Outdoor Leq(h)a

A tract of land where quiet is an essential element of their intended purpose. This category includes lands set aside for serenity and quiet and such land uses as outdoor amphitheaters and concert pavilions, as well as national historic landmarks with significant outdoor use. Also included are recording studios and concert halls.

2 Outdoor Ldn Residences and buildings in which people sleep. This category includes homes, hospitals, and hotels, where a nighttime sensitivity to noise is assumed to be of utmost importance.

3 Outdoor Leq(h)a

Institutional land uses with primarily daytime and evening use. This category includes schools, libraries, and churches, where it is important to avoid interference with such activities as speech, meditation, and concentration on reading material. Places for meditation or study associated with cemeteries, monuments, museums, campgrounds, and recreational facilities can also be considered to be in this category. Certain historical sites and parks are also included.

Source: FTA Guidance Manual, May 2006. Note: aLeq for the noisiest hour of transit-related activity during hours of noise sensitivity.

The FTA noise impact threshold is a sliding scale based on existing noise exposure and land use of sensitive receivers. The basic concept of the FTA noise impact criteria is that more project noise is allowed in areas where existing noise is higher. However, in areas where existing noise exposure is higher the allowable increase above the existing noise exposure decreases. For example, in an area with an existing noise level of 55 dBA, the allowable increase in noise level is 3 dBA which will result in a total future noise level of 58 dBA. For an area with an existing noise level of 60 dBA, the allowable increase in noise level is only 2 dBA, which will result in a total future noise level of 62 dBA.

FTA defines two levels of noise impact: moderate and severe. In accordance with the FTA Guidance Manual, mitigation to reduce noise levels must be considered for both degrees of impact. The manual also states that for severe impacts “…there is a presumption by FTA that mitigation is incorporated into the project unless there are truly extenuating circumstances which prevent it.” In considering mitigation for severe impacts in this study, the goal is to reduce noise levels to below the moderate impact threshold. FTA allows more discretion for mitigation of moderate impacts based on the consideration of factors including cost, number of sensitive receivers affected, community views, the amount by which the predicted levels exceed the impact threshold, and the sensitivity of the affected receivers.


The FTA noise impact criteria are given in tabular format in Table 8 with the thresholds rounded off to the nearest decibel. The criteria are shown graphically in Figure 3 for the different categories of land use along with an example of how the criteria are applied. The two graphs on the left are for nonresidential land uses where Leq(h) represents the noise exposure metric, and the top right graph is for residential land uses where Ldn represents the noise exposure metric. As shown in Figure 3, the impact threshold is a sliding scale and it typically increases with an increase in existing noise exposure. The existing noise appears on the horizontal axis, and the amount of new noise that the project can create is on the vertical axis. The lower curve (blue) defines the threshold for moderate impact and the upper curve (red) defines the threshold for severe impact.

The sample graph located in the bottom right corner of Figure 3 may help clarify the concept of a sliding scale for noise impact. Assume that the existing noise has been measured at 60 dBA Ldn. This is the total noise from all existing noise sources over a 24-hour period: traffic, aircraft, lawn mowers, children playing, birds chirping, etc. Starting at 60 dBA on the horizontal axis, follow the vertical line up to where it intersects the moderate and severe impact curves. Then refer to the left axis to see the impact thresholds. An existing noise of 60 dBA Ldn gives thresholds of 57.8 dBA Ldn for moderate impact and 63.4 dBA Ldn for severe impact. Note that the values are measured in tenths of a decibel to avoid confusion from rounding off; in reality, one cannot perceive a tenth of a decibel change in sound level.

Note that the curves in Figure 3 are defined in terms of project-only noise (on the vertical axes) and the existing noise (on the horizontal axes). The project-only noise is the noise introduced into the environment by the project; it is not the future noise levels with the project. The project-only noise does not include noise from existing noise sources in the area that won’t change as a result of the project such as automobile traffic and airplanes.

For TPSS units, the noise limit applied is more stringent than the FTA noise impact criteria to ensure no impacts are overlooked. A noise impact is indicated when the predicted TPSS nighttime Leq noise level exceeds the existing nighttime Leq minus 5 decibels.


FIGURE 3: FTA NOISE IMPACT CRITERIA


TABLE 8: FTA NOISE IMPACT CRITERIA Existing Noise

Exposure, Leq or Ldn Project Noise Exposure Impact Thresholds, Leq or Ldn

(dBA) Category 1 or 2 Land Uses Category 3 Land Uses

Moderate Impact Moderate Impact

Severe Impact

Moderate Impact

Severe Impact

<43 Ambient+10 Ambient+15 Ambient+15 Ambient+20 43 52 58 57 63 44 52 58 57 63 45 52 58 57 63 46 53 59 58 64 47 53 59 58 64 48 53 59 58 64 49 54 59 59 64 50 54 59 59 64 51 54 60 59 65 52 55 60 60 65 53 54 60 60 65 54 55 61 60 66 55 56 61 61 66 56 56 62 61 67 57 57 62 62 67 58 57 62 62 67 59 58 63 63 68 60 58 63 63 68 61 59 64 64 69 62 59 64 64 69 63 60 65 65 70 64 61 65 66 70 65 61 66 66 71 66 62 67 67 72 67 63 67 68 72 68 63 68 68 73 69 64 69 69 74 70 65 69 70 74 71 65 70 71 75 72 66 71 71 76 73 66 71 71 76 74 66 72 71 77 75 66 73 71 78 76 66 74 71 79 77 66 74 71 79

>77 66 75 71 80 Source: FTA Guidance Manual, May 2006. Note: Ldn is used for land uses where nighttime sensitivity is a factor; maximum one hour Leq is used for land use involving only daytime activities.


5.3 FTA IMPACT CRITERIA FOR GROUNDBORNE VIBRATION

The potential adverse effects of rail transit groundborne vibration include perceptible building vibration, rattle noises, reradiated noise (groundborne noise), and cosmetic or structural damage to buildings. The vibration caused by modern streetcar operations is well below what is considered necessary to damage buildings. Therefore, the criteria for building vibration caused by transit operations are only concerned with potential annoyance of building occupants.

The FTA vibration impact criteria are based on the maximum indoor vibration level as a train passes. There are no impact criteria for outdoor spaces such as parks. The FTA Guidance Manual (Ref. 1) provides two sets of criteria: one based on the overall vibration velocity level for use in General Vibration Impact Assessments and one based on the maximum vibration level in any 1/3 octave band (the band maximum level) for use with a Detailed Vibration Assessment. A 1/3 octave band is a range of frequencies and each 1/3 octave band is referred to by the center frequency in that band. Predicted vibration on a 1/3 octave band basis allows vibration mitigation to be designed for the frequency range in which it will be most effective. This study uses the Detailed Vibration Assessment criteria.

The criteria for use with Detailed Vibration Assessments are shown in Figure 4. The predicted vibration levels are compared to the criteria curves shown in Figure 4 to determine whether there is impact and the frequency range over which vibration mitigation is required. Impact is identified when the predicted vibration velocity in any 1/3 octave band exceeds the applicable curve. The VC-A through VC-E curves are used to specify acceptable vibration limits for sensitive equipment such as electron microscopes. The “Residential (Night)” curve is applied to residential land uses, similar to the Category 2 land use defined for the noise analysis. The “Residential (Day)” curve is applied to institutional land uses with primarily daytime use such as schools, libraries, and churches, and is similar to the Category 3 land use defined for the noise analysis. Table 9 provides a brief description of each of the curves shown in Figure 4.

The use of the criteria is illustrated by the example vibration spectra (the dashed blue line) shown in Figure 4. The maximum example level exceeds the “Residential (Night)” curve in the 50 and 63 Hz 1/3 octave bands. For this example, impact would be predicted for residential land uses, and vibration mitigation would be evaluated. However, no impact would be predicted for institutional land uses, because the example spectra does not exceed the “Residential (Day)” curve in any 1/3 octave band.

There are some buildings, such as concert halls, recording studios and theaters, which can be very sensitive to vibration but are not associated with the curves in Figure 4. Due to the sensitivity of these buildings, they usually warrant special attention during the Noise and Vibration Technical Report Page 30 May 2015 Environmental Assessment Tempe Streetcar

environmental evaluation of a transit project. Table 10 gives the FTA criteria for acceptable levels of groundborne vibration and groundborne noise for various categories of special buildings. These criteria are for limits on the overall vibration or noise levels, not the 1/3 octave band spectra.

The buildings along the project corridor where special building criteria apply are the Valley Art Theater, ASU Music Building and the Gammage Auditorium. The criteria for recording studios and concert halls listed in Table 10 have been used to evaluate potential vibration impacts to the ASU Music Building and the Gammage Auditorium, respectively. The criterion for theaters was applied to the Valley Art Theater.

FIGURE 4: FTA CRITERIA FOR DETAILED VIBRATION ANALYSIS


TABLE 9: INTERPRETATION OF VIBRATION CRITERIA FOR DETAILED ANALYSIS

Criterion Curve Max Lv1 (VdB)

Description of Uses

Workshop 90 Distinctly feelable vibration. Appropriate to workshops and non-sensitive areas.

Office 84 Feelable vibration. Appropriate to offices and non-sensitive areas.

Residential Day 78 Barely feelable vibration. Adequate for computer equipment and low-power optical microscopes (up to 20X).

Residential Night, Operating Rooms

72 Vibration not feelable, but groundborne noise may be audible inside quiet rooms. Suitable for medium-power optical microscopes (100X) and other equipment of low sensitivity.

VC-A 66 Adequate for medium- to high-power optical microscopes (400X), microbalances, optical balances, and similar specialized equipment.

VC-B 60 Adequate for high-power optical microscopes (1000X), inspection and lithography equipment to 3 micron line widths.

VC-C 54 Appropriate for most lithography and inspection equipment to 1 micron detail size.

VC-D 48 Suitable in most instances for the most demanding equipment, including electron microscopes operating to the limits of their capability.

VC-E 42 The most demanding criterion for extremely vibration-sensitive equipment.

Source, FTA 2006 (Ref. 1) Table 8-3 Notes: 1 Maximum allowed vibration velocity in any 1/3 octave band over the range of 8 to 80 Hz.

TABLE 10: GROUNDBORNE NOISE AND VIBRATION IMPACT CRITERIA FOR

SPECIAL BUILDINGS

Location Groundborne Vibration Impact Levels (VdB re 1 micro-inch/sec)

Groundborne Noise Impact Levels

(dB re 20 micro Pascals) Concert Halls 65 VdB 25 dBA

TV Studios 65 VdB 25 dBA

Recording Studios 65 VdB 25 dBA

Auditoriums 72 VdB 30 dBA

Theaters 72 VdB 35 dBA Source: FTA 2006 (Ref. 1) Table 8-2

The FTA guidance manual also presents criteria for assessing ground-borne noise impact for the sensitive land use categories other than the special buildings. Groundborne noise is caused by the vibration of room surfaces radiating sound waves. When audible groundborne noise occurs, it sounds like a low-frequency rumble. When the tracks are above ground, the groundborne noise is usually masked by the normal


airborne noise radiated from the rails and it is not necessary to assess impact from groundborne noise.

Table 11 shows the predicted groundborne noise level and indoor airborne noise level for a sensitive receiver located 50 feet from the tracks. The predicted levels are based on the noise and vibration models presented in Section 6.0. The indoor airborne noise levels assume a 25 decibel outdoor to indoor reduction in noise, which is typical for buildings with the windows closed. Table 11 shows the indoor noise would be about 11 decibels higher than the groundborne noise. Building specific factors influence both the indoor airborne and groundborne noise levels, so the predicted difference would vary throughout the corridor. However, it is unlikely the groundborne noise levels would be discernable above the airborne noise levels at most buildings throughout the corridor. Therefore, this report only assesses potential for impact from groundborne noise at the “special buildings” that typically have higher than normal outdoor to indoor noise reduction.

TABLE 11: COMPARISON OF INDOOR AIRBORNE AND GROUNDBORNE NOISE LEVELS

Train Noise Level, Lmax (dBA), 50 ft, 50 mph

Airborne noise level, indoors 47

Groundborne noise level, indoors1 36

Difference 11 Notes: 1 Assumes a Krad (room absorption) value of -5 dBA.

The FTA vibration thresholds do not specifically account for existing vibration. Although there are substantial volumes of vehicular traffic including buses and trucks in the project area, it is relatively rare that rubber-tired vehicles will generate perceptible ground vibration unless there are irregularities in the roadway surface such as potholes or wide expansion joints. As such, it is expected that current conditions along the proposed project corridor do not include more than isolated cases where traffic generated groundborne vibration is perceptible.

Note that historic structures that do not fall into the FTA land use categories are not included in the assessment for vibration impact from streetcar operations. The vibration impact thresholds are based on annoyance, and the primary concern for historic structures is the risk of damage. The recommended limit in the FTA guidance manual for buildings extremely susceptible to damage is 90 VdB, which is 18 decibels higher than the limit for Category 2 (residential) land uses. Vibration from streetcar operations Noise and Vibration Technical Report Page 33 May 2015 Environmental Assessment Tempe Streetcar

will be well below the limit for buildings extremely susceptible to damage at all historic resources.


6.0 NOISE AND VIBRATION METHODOLOGY

6.1 NOISE PREDICTION MODEL

This section describes the models that were used to predict noise related to the modern streetcar operations.

6.1.1 Noise from Streetcar Operations The noise prediction model follows the noise impact assessment methodology for detailed noise predictions presented in the FTA Guidance Manual and incorporates assumptions on operating conditions specific to the project, including speeds, vehicle type, and train frequencies.

For well-maintained streetcar systems, the wheel-rail noise dominates above 20 mph and the noise from propulsion motors, air conditioning, and other auxiliary equipment on the vehicles dominate below 20 mph. Streetcar noise is similar to light rail systems operating on embedded track. The noise predictions for this analysis are based on reference noise level measurements from the embedded sections of the Phoenix Metro (LRT) Starter Line with operating speeds similar to the major sections of the proposed streetcar alignment (please refer to Appendix C for further discussion on the reference data used for the noise predictions). The reference levels used for this analysis are:

• Maximum sound level (Lmax) of a one-car streetcar operating at 35 mph on embedded track at a distance of 50 ft: 77 dBA

• Streetcar speed: 25 mph • Streetcar length: 60 ft • Noise amplification from crossover frogs: +6 dB • Noise amplification from wheel squeal: +10 dB for any curve with radius less than

600 feet

These values were used with formulas included in the FTA Guidance Manual to predict the noise levels at each cluster of sensitive receivers. The principal formulas are:

Relationship between Lmax and the Sound Exposure Level (SEL):

( )( ) 3.32sin2log10max +

+×−= aa

lengthspeedLSEL

where: speed = Velocity in mph length = Length of the vehicle α = tan-1(length/2y), where y is the distance from receiver


to track centerline

Change in sound level with speed:

=∆

1

2log20 speedspeedSEL

where: 1speed = Reference speed (35 mph)

2speed = Predicted speed (25 mph) SEL∆ = Change in SEL for speed change from speed1 to speed2

The above speed relationship is valid for train speeds higher than 20 mph. The streetcars would be traveling about 25 mph, the posted speed limit for all roads. Because streetcars can accelerate to 25 mph fairly quickly, we assume a speed of 25 mph for all sensitive receivers.

Calculation of Ldn and hourly Leq from SEL:

𝐿𝐿𝐿𝐿𝐿𝐿 = 𝑆𝑆𝑆𝑆𝐿𝐿𝑟𝑟𝑟𝑟𝑟𝑟 + 10 log(𝑁𝑁𝑇𝑇𝑟𝑟𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇 + 𝑁𝑁𝑇𝑇𝑟𝑟𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝐺𝐺𝐺𝐺𝑇𝑇 × 10) − 10 log �𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷 𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝑟𝑟𝑟𝑟𝑟𝑟� � − 49.4

𝐿𝐿𝐿𝐿𝐿𝐿(ℎ𝑜𝑜𝑜𝑜𝑜𝑜) = 𝑆𝑆𝑆𝑆𝐿𝐿𝑟𝑟𝑟𝑟𝑟𝑟 + 10 log(𝑁𝑁𝑇𝑇𝑟𝑟𝑇𝑇𝑇𝑇𝑇𝑇𝐺𝐺𝑇𝑇𝑇𝑇𝑇𝑇) − 10 log �𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷 𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝑟𝑟𝑟𝑟𝑟𝑟� � − 35.6

where: NTrainDAY = Number of streetcars during daytime hours (7 AM to 10 PM) NTrainNIGHT = Number of streetcars during nighttime hours (10 PM to 7 AM) NTrainHOUR = Number of streetcars during one hour Dist = Distance from streetcar tracks to the sensitive receiver Distref = Reference distance (50 feet)

The proposed operating schedule is shown in Table 12. The predicted noise levels in Section 7.0 include streetcar operations between 12 AM and 3 AM to reflect worst-case noise conditions.

TABLE 12: PROPOSED STREETCAR OPERATING SCHEDULE Hours Frequency

5 AM - 6 AM 20 minutes 6 AM - 7 PM 10 minutes 7 PM - 12 AM 20 minutes 12 AM - 3 AM 20 minutes (Friday and Saturday only)


6.1.2 Prediction Model, Noise from Audible Warnings The bells would be installed at both ends of the streetcar vehicles and may be activated at the front or both front and rear ends. The noise from bells is modeled based on the bell sound level for the Phoenix LRT vehicles and the assumption that the bells are point sound sources. The bell reference sound level is assumed to be a maximum sound level (Lmax) of 80 dBA at a distance of 50 ft from the bell. Although the bells are mounted on the trains, the bells are modeled as a point sound source because it is expected that, in normal use, they will be sounded in two short intervals only 1) when stopping and starting from the streetcar stops and 2) at stoplights when the streetcar starts after stopping for the signals. A reasonable assumption is that approximately half of the trains would sound the bell at signaled intersections since the bells would only be sounded when the signal requires the streetcar to stop at an intersection. The bell noise model also assumes that the bells will be sounded by all trains when stopping and starting from streetcar stops.

The principal formulas used for this analysis are:

Relationship between Lmax and SEL: [ ]TLSEL log10max ×+=

where: T = Duration of the maximum bell noise

Calculation of Ldn and hourly Leq from SEL:

𝐿𝐿𝐿𝐿𝐿𝐿 = 𝑆𝑆𝑆𝑆𝐿𝐿𝐵𝐵𝑟𝑟𝐵𝐵𝐵𝐵 + 10 log(𝑁𝑁𝑇𝑇𝑟𝑟𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇 + 𝑁𝑁𝑇𝑇𝑟𝑟𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝐺𝐺𝐺𝐺𝑇𝑇𝑥𝑥10) − 20 log �𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷 𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝑟𝑟𝑟𝑟𝑟𝑟� � − 49.4

𝐿𝐿𝐿𝐿𝐿𝐿(ℎ𝑜𝑜𝑜𝑜𝑜𝑜) = 𝑆𝑆𝑆𝑆𝐿𝐿𝐵𝐵𝑟𝑟𝐵𝐵𝐵𝐵 + 10 log(𝑁𝑁𝑇𝑇𝑟𝑟𝑇𝑇𝑇𝑇𝑇𝑇𝐺𝐺𝑇𝑇𝑇𝑇𝑇𝑇) − 20 log �𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷 𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝑟𝑟𝑟𝑟𝑟𝑟� � − 35.6

where: NTrainDAY = Number of trains sounding bell during daytime hours NTrainNIGHT = Number of trains sounding bell during nighttime hours NTrainHOUR = Number of trains sounding bell during one hour Dist = Distance from the bell to the sensitive receiver Distref = Reference distance (50 feet)


6.1.3 Ancillary Equipment The only ancillary equipment expected to have the potential of causing noise impacts are the traction power substation (TPSS) units. The primary noise sources from the TPSS units are the transformer hum and noise from cooling systems. On most modern TPSS units the transformer hum is minimal so only the ventilation and cooling system has potential to cause noise impacts.

A recent noise measurement of a TPSS unit used in a residential area along the Los Angeles Metro Gold Line showed that the ventilation fan generated a sound level of 51 dBA at a distance of 40 feet from the fan, which is equivalent to an Leq of 49 dBA at a distance of 50 feet (the measurement was not done at 50 feet because of obstructions). The measured noise level is consistent with the limit of 50 dBA at 50 feet from any side of the TPSS that has been included in the purchase specifications for TPSS units on several recently completed light rail systems. It has been assumed that similar units will be used on the Tempe Streetcar project.

The following formula is used to estimate TPSS noise for this project:

×−= Dref

DLpLp ref log20

where: D = Distance to receiver from the TPSS unit cooling fan Dref = Reference distance from the TPSS unit cooling fan (50 ft) Lp = Level of TPSS noise at receiver Lpref = TPSS sound level at reference distance (50 dBA)

6.1.4 Road Traffic Analysis Road traffic noise is analyzed using the FHWA Traffic Noise Model (TNM). This is done only at one location, as described further in Section 7.2.

6.2 VIBRATION PREDICTION MODEL

Localized geologic conditions such as such soil stiffness, soil layering, and depth to bedrock, have a strong effect on groundborne vibration. However, it is difficult to obtain information on subsurface conditions in sufficient detail that computer models can be used to accurately predict ground vibration. As a result, most detailed predictions of ground vibration are based largely on empirical methods that involve measuring vibration propagation in the soil.


The predictions of groundborne vibration for this study follow the Detailed Vibration Assessment procedure of the FTA Guidance Manual (Ref. 1). This is an entirely empirical method based on testing of the vibration propagation characteristics of the soil in the project corridor and measurements of the vibration characteristics of a similar streetcar vehicle. The quantity derived from propagation tests is referred to as the Line Source Transfer Mobility (LSTM). The LSTM is used with the Force Density Level (FDL)—a measure of how much vibration energy trains generate—to predict the vibration energy received by the sensitive receivers.

The basic relationship used for the vibration predictions is:

Lv = FDL + LSTM

where: Lv = Train vibration velocity measured at the ground surface LSTM = Measured line source transfer mobility FDL = Force density function that characterizes the vibration forces generated by the train and track (All quantities are expressed in decibels using a consistent set of decibel reference values)

To predict impacts, this Lv is combined with receiver-specific adjustments—such as speed, special trackwork, coupling loss, floor amplification, and other factors—and compared against the regulatory limits discussed in Section 5.3. These adjustments are discussed in a later section.

The FDL used for this project was developed from measurements of trains running on the existing Seattle SLU Streetcar and Portland Streetcar systems. Appendix B is a summary of the results of the streetcar measurements in Seattle and Portland and the derived FDL.

The LSTM was calculated at eight locations that were selected to represent the vibration sensitive receivers along the Tempe Streetcar corridor. The sites were spaced by approximately 0.5 miles. The measurements included transfer mobilities into indoor spaces at four of the locations. Figure 2, on Page 19, shows where the vibration sites are located along the alignment.

The average LSTM of all measured sites along the alignment was used in the vibration prediction model. The variation in the measured LSTM among sites was factored into the prediction model using a safety factor discussed in Section 6.2.5.


The LSTM and FDL are both empirically derived quantities. The methodology used to derive these values for each receiver in the prediction model is discussed in the following subsections.


6.2.1 Vibration Propagation Test Procedure The vibration predictions for the Tempe Streetcar project are based on the Detailed Assessment approach recommended in the FTA Guidance Manual. The FTA Detailed Vibration Assessment uses state-of-the-art tools to characterize how localized soil conditions affect the levels of groundborne vibration. A vibration propagation test is conducted to measure how vibration is transmitted from the streetcar tracks through the ground and into the foundations of nearby buildings (see Figure 5).

FIGURE 5: SCHEMATIC OF VIBRATION PROPAGATION TEST

The test procedure consists of creating an impact force using a dropped weight and determining the transfer function relationship between the force generated by the dropped weight and the resulting vibration pulse. The impacts using the dropped weight are performed in a line located as close to the planned track centerline as possible and vibration sensors are located at several distances from the impact line. Sensors may also be located inside nearby buildings to provide information on the propagation path from the track centerline to the building’s occupied spaces. Vibration propagation tests were performed at eight locations in Tempe, each using a line of 11 impact positions at intervals of 15 ft (marked as the line of impacts in Figure 5).

The relationship between the exciting force and the resulting vibration level is referred to as the “transfer mobility,” which indicates how easily vibration travels through the earth. Each of the 11 impact positions yield a point-source transfer mobility. Numerically integrating the 11 point-source transfer mobilities yields a line-source transfer mobility (LSTM). Each accelerometer yield its own LSTM at a different distance which can be fit to a LSTM-vs-log(distance) curve to predict LSTM as a function of distance.


6.2.2 Vibration Propagation Test Sites The eight locations for the vibration propagation tests were selected to represent the vibration sensitive receivers along the Tempe Streetcar corridor. The sites were spaced by approximately a half- mile. The measurements included transfer mobilities into indoor spaces at four of the locations. The location of sensors and force-impacts at each measurement site is shown in Figure 48 through Figure 55 in Appendix D.2.

The details of the vibration propagations sites are discussed below:

V-3 St. Luke Hospital: This measurement was performed at the St. Luke Hospital in the northern parking area. The line of impacts was located on the western curbside of Mill Avenue. Two sensors were located on the front lawn outside the hospital property line and four sensors were located in the parking area of the hospital. The sensors were located at 25, 37, 50, 75, 100 and 150 feet from the impact line. Figure 48 shows the aerial view of vibration propagation test site V-3.

V-4 ASU Music Building: This measurement was performed at the ASU Music Building located adjacent to the Gammage Auditorium. This site included five outdoor measurement positions and two indoor measurement positions. The indoor positions were included at this site to determine the effects of groundborne noise and vibration at the music facilities. The impact line was located on the eastern curbside of Mill Avenue. The outdoor sensors were mounted at 25, 37, 50, 75 and 90 feet from the impact line. The 90-feet sensor position was the setback distance of the Music Building. In addition, one sensor was mounted on the 1st floor of the Music Building in the Jazz Rehearsal Hall and a second sensor was located on the 2nd floor in the W 230 Electronic Music Studio No.1. Figure 49 shows the aerial view of vibration propagation test site V-4.

V-5 University Inn: This measurement was performed at the University Inn located at the southwest intersection of Mill Avenue and E 9th Street. The impact line at this site was located along the western curbside of Mill Avenue and the hotel building was setback 15 feet from the impact line. All accelerometers were mounted within the hotel property line. Vibration sensors were placed along the outdoor patio/parking area of the hotel at distances of 25, 50, 75 and 100 feet from the impact line. In addition one sensor was placed in the 1st floor office space which is an extension of the living area of the hotel owner, and another sensor was placed in the 2nd floor guest room 201. Figure 50 shows the aerial view of vibration propagation test site V-5.

V-6 Ash Avenue/5th Street: This measurement site was located north of the intersection at Ash Avenue and E 5th Street. The impact line was located on the eastern curbside of Ash Avenue and the sensors were mounted on the parking lot located west of Hayden Square Condos. The sensors were located at 25, 37, 50, 75, 100 and 150


feet from the impact line. Figure 51 shows the aerial view of vibration propagation test site V-6.

V-11 Bridgeview Condos: This measurement was performed at the Bridgeview Condos at 140 E Rio Salado Parkway. An empty lot to the west of the complex—where a hotel is planned for construction—was used. The line of impacts ran across the southern edge of the lot on the dirt, about 3 feet from the sidewalk. This site included six outdoor sensors and two indoor sensors. The outdoor sensors were located at 25, 37, 50, 75, 100 and 150 feet from the impact line. The indoor sensors were located in the hall outside Room 201, in the middle of the club room on floor 1, and in a parking space at ground level. Figure 52 shows the aerial view of vibration propagation test site V-11.

V-12 Valley Art Theater: This measurement location differed from that made for the noise measurement (permission to gain access to the property to conduct vibration measurements could not be obtained during the time that noise measurements were made). This measurement was located near the intersection of S Mill Avenue and 4th Street. The impact line ran along the eastern (northbound) shoulder of Mill Avenue. The sensors were mounted at 25, 37, 50, 75, 100 and 150 feet from the impact line. Figure 53 shows the aerial view of vibration propagation test site V-12.

V-13 Vista Del Sol Apts: This measurement was performed at the Vista Del Sol apartment complex on E Apache Blvd between S McAllister Ave and Paseo del Saber. The impact line ran along the sidewalk on the south-side of Apache Blvd, about 10 feet from the curb. The sensors ran along the emergency access alley between Towers I and J. Six sensors were placed outdoor and 2 were placed indoor. The outdoor sensors were located 25, 37, 55, 80, 100 and 150 feet from the impact line. The apartment building was in line with the 37-feet sensor. The indoor sensors were placed in rooms 1119 and 2119, which are respectively at ground level and one floor above ground level. Figure 54 shows the aerial view of vibration propagation test site V-13.

V-14 Sonoran Ridge Apts: This measurement site was located at the Sonoran Ridge Apartments at 1205 E Apache Blvd. The impact line was located on the sidewalk between Apache Blvd and the apartment complex. The line of sensors ran from the impact line into apartment unit 110. Four outdoor sensors, two indoor sensors, and two backyard sensors were used. The outdoor sensors were located at 25, 37, 50, and 100 feet from the impact line. The indoor sensors were located in the ground-level kitchen and the upstairs bedroom closest to the street. The backyard sensors were placed on the back patio and in the yard approximately 137 and 143 feet from the impact line. The indoor sensors were about 110 feet from the impact line. Figure 55 shows the aerial view of vibration propagation test site V-6. It should be noted that this measurement location also represents the Lennar Development, which will replace the Sonoran Ridge Apartments.


6.2.3 Applying Vibration Propagation Test Results to Prediction Model The measured LSTMs and coherences for each vibration propagation test site are shown in Appendix D.3. The LSTMs for each site were used to create best-fit curves of LSTM vs log-distance. The best-fit coefficients are presented in Appendix D.4.

Figure 6 shows two plots. On the left is the LSTM at 25 ft produced using the coefficients found at each site. On the right are three lines representing the max, mean, and min for each 1/3 octave band of the plot on the left.

Below is a summary of the key observations from Figure 6: • The LSTMs across test sites have spectral peaks around 40 Hz. • All test sites have a single-peak, broad-shaped spectrum except for site V-11

which appears to have a secondary smaller peak around 16 Hz and/or a valley around 20 Hz. This peak is more prominent in the closer sensor positions and may be caused by a localized condition. The averaging of the eight sites minimizes this affect.

• The difference between the maximum and average is typically less than 5 dB on most bands, especially those of higher coherence and importance to the model.

• The standard deviation among LSTM values at 40 Hz is about 3 dB. The average standard deviation among all bands is closer to 5 dB.

• The LSTMs tend to fall off with distance at similar rates across test sites, which is why the average of all tests sites for each location is used.

Figure 7 shows the maximum, mean, and minimum for 4 setback distances. The goal of these plots is to illustrate the distribution of measured values across the alignment and provide the basis for the calculation of the final best-fit LSTM curve coefficients. The mean LSTM (labeled “Avg Band Value” on the plot) is very similar in shape and amplitude to several measured LSTMs (compare to V-13, V-14, V-5) and therefore was chosen as the most logical choice for representing the predicted LSTM in shape and amplitude. At the spectral maxima (around the 31.5 Hz to 40 Hz bands) the difference between the maximum and average was no more than 5 dB. This margin was taken into account in the safety factor as discussed in Section 6.2.5.

To construction the final LSTM curve used in the prediction model, the average LSTM for each distance (shown in Figure 7) were incorporated into a best-fit curve for LSTM-vs-log(distance) for each 1/3 octave band. The best fit coefficients are shown in Table 13.


FIGURE 6: MEASURED LSTM AT 25 FT AND MAX, MIN, AVG LSTM AT 25 FT

FIGURE 7: BEST FIT LSTM – MAX, MIN, AVG OF ALL SITES


The equation used for the fit is as follows:

LSTM(d) = A + B*log(d) + C*log(d)2

where: LSTM = Line Source Transfer Mobility in dB re 1 (µin/sec)/(lb/ft1/2) d = Distance in feet

TABLE 13: LSTM COEFFICIENTS FOR PREDICTION MODEL

Frequency A B C 6.3 27.5 -12.7 8 30.1 -14.2 10 35.7 -13.8

12.5 42.2 -12.0 16 40.7 -7.5 20 50.1 -11.5 25 60.7 -15.7

31.5 -39.3 117.8 -41.4 40 36.0 31.4 -16.6 50 -4.6 89.2 -37.2 63 30.1 43.5 -24.4 80 20.8 46.0 -25.2

100 49.1 16.6 -20.1 125 114.9 -61.0 160 104.0 -58.7 200 98.7 -56.6 250 68.3 -39.7 315 48.6 -31.2

6.2.4 FDL Force density level (FDL) is derived by measuring Vibration Levels (Lv) and Line Source Transfer Mobility (LSTM) at a site where there are already streetcar operations and calculating the FDL using the equation: Lv = FDL + LSTM. Since this project is a new streetcar project, it does not benefit from having existing streetcars. Instead, the prediction model relies on FDLs from similar systems with streetcars. For this project, the FDL of the Portland and Seattle Streetcar systems were measured in July 2011 and combined with Portland Streetcar measurements from July 2006. The results of the FDL measurements at this site are shown in Figure 8 for streetcar speeds of 25 mph. Details of the FDL tests and results are given in Appendix B. The FDL does not show any remarkable peaks across the spectrum (Figure 8). As discussed in Appendix B, a low


FDL can be maintained in streetcar systems through a program that manages optimal streetcar wheel-rail profile and pro-actively eliminates potential for wheel deformations.

FIGURE 8: STREETCAR FORCE DENSITY LEVEL AT 25 MPH

6.2.5 Adjustments of Lv for Prediction Model After determining the FDL and LSTM discussed in the previous sections, the following adjustments were incorporated into the prediction model to estimate vibration levels in occupied spaces of buildings:

• Speed Adjustment: The streetcar is expected to have a top speed of 25 mph along the corridor. As a worst case scenario, this speed has been used in the predictions across the entire project regardless of whether trains are expected to slow down when approaching a stop. Since the composite FDL represents a train traveling at 25 mph, no additional adjustments for speed are necessary. As a note, the composite FDL was formed using trains traveling at 25 mph or whose levels were normalized to 25 mph using a speed adjustment factor of 15*log(speed).

• Special Trackwork: The additional vibration at special trackwork was accounted for by adding 10 decibels to the predicted vibration levels when the special trackwork frog will be located less than 100 feet from a sensitive receiver.

• Theoretical Coupling Loss and Floor Amplification: Two things happen as vibration is transmitted from the ground, into the building foundation, and through the building into occupied spaces. First, the interaction at the soil/foundation


interface tends to reduce the vibration amplitudes transmitted into the building foundation. Second, when the vibration reaches occupied spaces of the building, various resonances in the building components can amplify the vibration. Both of these effects can be substantial and are difficult to predict. The FTA Manual suggests +6 dB for floor amplification and −2 dB per floor for floor-to-floor attenuation up to five floors above grade. For coupling loss, the FTA Manual suggests a −5 dB adjustment for lightweight wood-frame structures and a −10 dB adjustment for large masonry buildings. Combining the adjustment factors for a wood-frame structure such as a residence, there is −5 dB for the coupling loss, +6 dB for floor amplification, and an additional −1 to −2 dB for each floor above the grade level. This leads to a net adjustment of between −1 to +1 dB for the vibration inside a typical residence. Therefore, no adjustment is applied to account for coupling loss and floor amplification in the prediction model.

• Measured Building Amplification and Safety Factor: Figure 9 and Figure 10 show the measured indoor amplification for 1st (ground) floor sensors and 2nd floor sensors along the Tempe Streetcar project. In general, there appears to be a net average absorption on first floor receivers and a net average amplification on second floor receivers. The degree of these amplifications is extremely variable and dependent on the specifics of the building measured. It is not feasible to consider each receiver individually without a considerable amount of additional measurements. Therefore, in order to account for potential amplification effects from buildings and other possible sources of error in the predictions a safety factor of +5 dB was added to each 1/3 octave band. This is a conservative approach that ensures that in the majority of cases the predicted vibration levels are higher than what will occur after the proposed project is operational.


FIGURE 9: INDOOR VIBRATION AMPLIFICATION, 1ST (GROUND) FLOOR

FIGURE 10: INDOOR VIBRATION AMPLIFICATION, 2ND FLOOR


6.2.6 Final Vibration Prediction Model Figure 11 presents the predicted vibration level, Lv, with a +5 VdB safety factor (see Section 6.2.5 for explanation) at various distances. Also plotted are two FTA criteria for impact for residential land uses. Figure 11 illustrates how, using this model, residential receivers within 50 feet of the alignment will exceed the FTA Residential (night) criteria. Only a single 1/3 octave band Lv needs to exceed 72 VdB for the residential receiver to be considered an impact. Note that the FTA criteria for a detailed vibration impact assessment uses the Residential (Night) criteria curve for land uses where people sleep including residences and hotels and the Residential (Day) criteria curve for institutional land uses like schools and churches.

FIGURE 11: PREDICTED STREETCAR VIBRATION SPECTRUM AT 25 MPH (Curves include a +5 VdB safety factor)

6.2.7 Special Land Uses In some cases, site-specific measurement results were used to evaluate vibration impact at the land uses classified in the FTA guidance manual as “special buildings”. Following is a description of the assumptions used in the prediction models for the “special buildings”:

• The Valley Art Theater on Mill Ave used an LSTM curve from one of the eight measurement sites. The closest measurement site was V-12, which was about 550 feet north on Mill Ave from the theater. The LSTM from this site alone was


used instead of the one derived from the average of all sites’ LSTMs. The distance used to estimate the vibration levels for this site is that from the future streetcar alignment to the screening room. There may be additional energy entering the screening room from building affects and other circumstances unique to this property. Additional testing during final design could clarify if this is an issue.

• The ASU Music Building on Mill Ave used measurements at the site in the rooms of interest to predict vibration levels. The LSTM calculated from the sensors placed in the Jazz Rehearsal Hall and Room W230 (Electronic Music Studio No. 1) were used to predict vibration levels in these rooms.

• The Gammage Auditorium did not have site-specific measurements so the generic approach was used.

These “special buildings” uses also required the assessment of groundborne noise. The process of calculating the groundborne noise is as follows.

• First, find the predicted groundborne vibration levels using the approach above. • Second, apply an A-weighting to the 1/3 octave spectrum. • Third, add a Krad factor of -5 decibels to account for the acoustical absorption in

the room. • Fourth, sum the sound energy into an overall noise level which represents the

groundborne noise level. • Fifth, compare this value to the FTA criteria for groundborne noise for “special

buildings”.


7.0 POTENTIAL OPERATIONAL NOISE AND VIBRATION IMPACTS AND MITIGATION

7.1 STREETCAR RELATED NOISE

7.1.1 Operational Noise The noise sensitive land uses for FTA Categories 1, 2 and 3 along the Tempe Streetcar project have been grouped into clusters. The clusters group similar land uses that are about the same distance from the tracks and are small enough that streetcar speeds and other operational parameters are the same for all receivers in the cluster. The locations of the clusters and buildings included in each cluster are shown in Appendix F Sensitive Receiver Inventory. The noise predictions are based on the sensitive receiver within each cluster that is closest to the Tempe Streetcar project.

Table 14 shows the predicted noise levels from streetcar operations for Category 1 land uses. Table 15 presents the predicted noise levels from streetcar operations for Category 2 land use clusters, and Table 16 presents the predictions for Category 3 land use clusters. Category 1 (highly sensitive) land uses along the corridor include the ASU Music Building, the Gammage Auditorium, and the Valley Art Theater. Category 2 land uses include residences and hotels. Category 3 land uses include a school, places of worship, institutional offices, Tempe Post Office, a clinic, and two parks that are not sensitive to noise during nighttime hours.

The columns in the tables provide the following information:

• ID: Identification for sensitive receiver cluster. Note that identification numbers were not used for Category 1 land use.

• Desc.: Describes the type of land use or name of the receiver. • Near Track Dist: Distance in feet from the near track centerline to the closest part

of the noise sensitive building or group of buildings. • Speed: Maximum expected train speed on the track closest to the sensitive

receiver. The speeds were based on the projected speed profile. The actual train speeds would often be lower near streetcar stops and signal stops.

• Exist Noise Site: Indicates which noise measurement site was used to represent the existing noise.

• Existing: Estimated existing noise level (Leq for Categories 1 and 3, Ldn for Category 2) at each sensitive receiver cluster based on the existing noise measurement results.

• Project: Predicted future Leq or Ldn from train noise. The noise predictions include bell noise from the streetcars at stops and stoplights. The streetcar bell


noise is included for all sensitive receivers that are located within 100 feet of a streetcar stop or an intersection with stoplights.

• Impact Threshold: The FTA impact thresholds for moderate and severe impact are based on the existing noise levels.

• Number of Impacts: The number of dwelling units for each sensitive receiver where the predicted levels of streetcar noise exceed the Moderate (Mod) and Severe impact thresholds.

Following is the summary of the noise impact assessment of the proposed Build Alternative:

• No noise impacts are predicted from streetcar operations at Category 1 land uses (Table 14).

• Moderate noise impacts of 1 dB or less are predicted from streetcar operations at seven Category 2 land uses (residential or other sensitive receivers with both daytime and nighttime use, e.g., residences, hotels, motels) as shown in Table 15. Five of these land uses are single-family residences, one is a hotel (72 units impacted), and one is an ASU residence hall (45 units impacted). All of the receivers where impact is predicted are located near the curve as the tracks transition from Mill Avenue onto Apache Boulevard. Predicted streetcar noise levels are higher at sensitive receivers located near a curve because wheel squeal often occurs on curves and can increase noise levels by as much as 10 decibels.

• No noise impacts are predicted from streetcar operations at Category 3 (Institutional with primarily daytime use) land uses as shown in Table 16.

TABLE 14: SUMMARY OF NOISE IMPACT ASSESSMENT FOR CATEGORY 1

Desc.a Near Track Dist. (ft)

Speed

(mph) Exist Noise Site

Leq, (dBA) # of Impacts

Existing Project b Impact

Threshold Mod Severe Mod Severe

Valley Art Theater 27 25 N15 68 55 63 68 -- -- ASU Music Building 96 25 N17 64 55c 60 66 -- --

Gammage Auditorium 258 25 LT3 59 48 57 63 -- -- Notes: a. Desc.= Name of receiver. b. Maximum 1-hour Leq during daytime when facility is in use. c. Includes streetcar bell noise at the stoplights or streetcar stops.



ID* Desc.a Near Track Dist. (ft)

Sensitive Receiver Location

Speed

(mph)

Exist Noise Site

Ldn b, (dBA) # of Impactsd

Existing Project c Impact


R1 MFR 75 Bridgeview Condos E Rio Salado Pkwy 25 N11 68 53 63 68 -- --

R2 MFR 222 Hayden Condos 154 W 5th St 25 N13 64 46 60 66 -- --

R3 Hotel 59 Courtyard Hotel 25 N13 74 55f 65 73 -- -- R4 MFR 196 111 6th St Condos 25 N13 65 46 61 66 -- --

R5 MFR 198 Encore on Farmer Senior Housing

25 N13 64 46 60 65 -- --

R6 Hotel 51 University Inn & Suites

25 N16 73 62 e,f 65 72 -- --

R7 MFR 66 918 S Mill Ave 25 N16 70 58 e 65 70 -- -- R8 SFR 70 1100 S Mill Ave 25 N16 70 64 f,g 64 69 1 -- R9 SFR 68 1104 S Mill Ave 25 N16 70 63 g 64 69 -- -- R10 SFR 70 1110 S Mill Ave 25 N16 70 63 g 64 69 -- --

R10A SFR 71 1112 S Mill Ave 25 N16 70 63 g 64 69 -- -- R11 SFR 83 1160 S Mill Ave 25 N16 67 63 g 62 68 1 -- R12 SFR 95 1170 S Mill Ave 25 N16 67 62 g 62 67 1 -- R13 SFR 107 1190 S Mill Ave 25 N16 66 62 g 62 67 1 -- R14 SFR 155 1202 S Mill Ave 25 N21 65 60 g 61 66 -- -- R15 SFR 182 1204 S Mill Ave 25 N21 65 60 g 61 66 -- -- R16 SFR 219 1208 S Mill Ave 25 N21 64 59 g 60 65 -- -- R17 SFR 210 21 E 13th St 25 N21 64 59 g 60 65 -- -- R18 SFR 173 25 E 13th St 25 N21 65 60 g 61 66 -- -- R19 SFR 142 33 E 13th St 25 N21 66 61 g 61 67 1 -- R20 Hotel 128 Graduate Hotel 25 N18 65 61 g 61 66 72 --

R21 MFR 88 ASU Residence Halls Hayden 25 N18 67 63 f, g 62 67 45 --

R22 MFR 50 ASU Student Housing Villas at Vista Del Sol 25 N18 69 60 f 64 69 -- --

R23 MFR 70 ASU Student Housing Vista Del Sol Towers

I, J, & K 25 N18 68 57 f 63 68 -- --

R24 MFR 61 ASU Student Housing Adelphi Commons

25 N18 68 54 63 68 -- --

R25 MFR 58

ASU Residence Halls Chuparosa, Jojoba,

Agave, Sage, Cereus, Cottonwood, Juniper

25 N18 70 58 f 64 69 -- --

R26 MFR 43 922 E Apache Blvd 25 N19 71 57 f 65 70 -- -- R27 MFR 48 977 E Apache Blvd 25 N19 70 55 65 70 -- -- R28 Hotel 66 Super 8 Hotel 25 N19 68 54 63 68 -- -- R29 Hotel 87 Holiday Inn Express 25 N19 67 52 62 68 -- -- R30 MFR 68 1123 E Apache Blvd 25 N19 68 54 63 68 -- -- R33 MFR 140 Sunset Villas Apts 25 N19 71 55 65 70 -- -- R34 Hotel 175 Tempe Mission Palms 25 N13 65 47 61 66 -- --

R35 SFR (4) 220 S Maple Avenue Homes 25 N16 63 49 60 65 -- --




Speed

(mph)

Exist Noise Site

Ldn b, (dBA) # of Impactsd

Existing Project c Impact


R36 MFR 44 Lennar Development 25 N19 73 58 65 71 -- -- Notes: a. Desc.=Type of land use, SFR=single-family residence, MFR=multi-family residence. b. Ldn values are rounded off to the nearest whole number unless shown otherwise. c. Project Ldn is the additional noise that would be created by the streetcar operations. d. Number of Impacts. This is a count of the number of SFR in the cluster plus the estimated number of residential units in multi-family buildings, rooms in motels/hotels where people sleep. e. Includes +6 dB amplification from special trackwork. f. Includes streetcar bell noise at the stoplights or streetcar stops. g. Includes wheel squeal noise from small radius curves. Note that the sensitive receiver locations are provided in Appendix F (Sensitive Receiver Inventory). * R31 and R32 are not listed in this table; the Sonoran Ridge Apartments (R31) and Days Inn (R32) are replaced with the Lennar Development (R36).



ID* Receiver Near Track Dist. (ft)

Speed

(mph) Exist Noise Site

Leq, (dBA) # of Impacts

Existing Project a Impact


I1 Tempe Beach Park 54 W Rio Salado Pkwy 24 25 N12 72 52 70 76 -- --

I2 Brickyard Engr. Bldg. 699 S Mill Ave

40 25 N16 66 53 c 67 72 -- --

I3 Tempe Post Office 500 S Mill Ave

80 25 N15 65 52c 66 71 -- --

I4

ASU building (use unknown, previously

Ceramic Research Center) 10th and Mill

81 25 N16 63 57 b,c 65 70 -- --

I5 Hillel Jewish Student

Center 1012 S Mill Ave

57 25 N16 68 58 b,c 68 73 -- --

I6 Alleluia Lutheran Student

School 1034 S Mill Ave

69 25 N16 66 53 b,c 67 72 -- --

I8 Birchett Park

adjacent to Gammage Curve

30 25 N21 70 63 d 70 75 -- --

I9 7th Day Adventist Church 41 E 13th St 110 25 N21 63 58 d 65 70 -- --

I10 Ten40 Church 1040 E Apache Blvd 170 25 N19 61 46 63 69 -- --

I11 Southwest Institute of Healing Arts (school) 1100 E Apache Blvd

98 25 N19 63 49 65 70 -- --

I12 Southwest Institute of

Natural Aesthetics (school) 1112 E Apache Blvd

163 25 N19 61 47 63 69 -- --

I13 New School for the Arts

and Academics 2016 E Apache Blvd

96 25 N20 62 48 b 64 70 -- --

Notes: a. Maximum 1-hour Leq that would be created by the streetcar operations during daytime when facility is in use. b. Includes +6 dB amplification from special trackwork. c. Includes streetcar bell noise at the stoplights or streetcar stops. d. Includes wheel squeal noise from small radius curves. * There is no I7 listed in this table; this identification was previously assigned to Chabad at ASU, which appears to now be located farther from the alignment. The sensitive receiver is now a residential land use, listed as receiver R10A in Category 2.

7.1.2 Ancillary Equipment Traction power substation (TPSS) units are the only ancillary equipment associated with the proposed project with the potential to cause noise impacts. A total of eight optional locations for the TPSSs are under consideration although the project will likely require


fewer than eight TPSS units along the 3.1-mile alignment. The locations of the TPSS units are shown in the receiver drawings in Appendix F. Several of the selected sites are adjacent to residential land uses. It is common to include noise limits in the purchase specifications for TPSS units to minimize the potential for noise impacts from TPSS noise. The specifications generally include maximum noise limits for potential noise generators, such as the transformer hum and any cooling systems. The cooling fans are the major noise source on many modern TPSS units and the transformer hum is usually inaudible except very close to the TPSS unit.

The typically adopted design goal for noise from TPSS units is at least 5 decibels lower than the nighttime ambient level. This is lower than the FTA noise impact criteria, but is appropriate because controlling TPSS noise usually is straightforward and rarely adds more than marginally to the cost. The first step in controlling TPSS noise is to include a noise limit in the purchase specifications for TPSS units. The recommended limit is that the maximum noise level not exceed 50 dBA at a distance of 50 feet from any part of a TPSS unit. In addition, the cooling fans should be oriented away from the nearest receiver in order to minimize the noise.

Table 17 shows the predicted levels of TPSS noise at the residence nearest to each of the proposed TPSS sites along with the measured nighttime Leq for the site. A noise impact is indicated when the predicted TPSS nighttime Leq noise level exceeds the existing nighttime Leq minus 5 decibels. This approach for assessing TPSS noise impact is more stringent than the FTA impact criteria and ensures no impacts are overlooked. As seen in Table 17, impact is predicted at the sensitive receivers closest to the University Drive / Mill Avenue TPSS site, where the predicted level matches the criteria. This TPSS site (designated as the U/M Option in the Environmental Assessment conceptual drawings) is located within 50 feet of the facade of the nearest home of the four grouped-together single-family residences on Maple Avenue between University Drive and 9th Street (identified as receiver R35; see Appendix F for map). (Note: Although the receiver near TPSS unit 7, 13th/Mill is closer to the nearest residence than the one with the predicted impact, TPSS unit 6, the existing noise levels are higher near unit 7, which results in no predicted impact in that area.)


TABLE 17: PREDICTED TPSS NOISE TPSS Unit Site

Location Nearest Residence

Existing Nighttime Leq (dBA)a

Predicted TPSS Leq

(dBA) b

Impact Threshold

(dBA) Impact

1 Rio Salado Pkwy / Packard OPTION 2 1020 ft -- -- -- No

2 Rio Salado Pkwy / Packard OPTION 1 850 ft -- -- -- No

3 Rio Salado Pkwy / Ash Ave 300 ft 58 34 53 No

4 3rd St / Ash Ave 120 ft 58 42 53 No 5 3rd St / Mill Ave 190 ft 53 38 48 No 6 University Dr / Mill Ave 50 ft 55 50 50 Yes 7 13th St / Mill Ave 40 ft 61 52 56 No

8 Terrance Rd / Apache Blvd 95 ft 56 44 51 No

Notes: a Nighttime Leq measured between the hours of 10pm to 7am. b Predicted TPSS noise is based on a maximum noise level of 50 dBA at 50 ft from any part of the TPSS.

7.2 TRAFFIC NOISE DUE TO ROADWAY CHANGES AND TRAFFIC VOLUME INCREASES

The Tempe Streetcar project involves a few roadway changes as described in the Introduction. Only one change has the potential to increase received road traffic noise levels, and this is the only section of the alignment that warrants a traffic noise analysis. As part of the project, a roadway travel lane (through lane) is being added to the East of the existing travel lane in the northbound section of Mill Avenue between University and 11th Streets. Roadway vehicles and the streetcar would share the existing travel lane, and roadway vehicles would then also be able to use the new travel lane. This results in part of the traffic being one lane width closer to sensitive receivers on the northbound side in that section of Mill Avenue. A traffic noise model analysis using the FHWA Traffic Noise Model (TNM) shows that the change in noise that would result in half of the traffic shifting closer to the receivers (outward one lane width) is minimal (less than one decibel). Therefore, the change in noise level that would result from the change in traffic patterns is not included as a noise source in the analysis (road traffic noise is not included in project noise predictions).

Note that the Tempe Streetcar project will not result in a 10% change (up or down) in traffic in 2035 (compared to the No-Build case) due to the streetcar project itself; this is based on the region’s travel demand model traffic projections, the ASU Master Plan Update, and the Tempe Transportation Master Plan. Because the change in traffic volume due to the project is negligible, a traffic noise analysis related to volume is not warranted.


7.3 STREETCAR OPERATIONAL VIBRATION

As discussed in 5.3, the FTA guidance manual provides two criteria for assessing vibration impacts. The first criterion is based on the overall vibration velocity level and is intended for use with a General Assessment. The second FTA criterion is based on the 1/3 octave band spectrum of the predicted vibration. FTA indicates that the second criterion is intended for use with a Detailed Assessment when vibration propagation testing has been performed and the predictions include the vibration spectrum. Note that there are no impact criteria for outdoor spaces.

As discussed in Section 6.2 (Vibration Prediction Model), vibration propagation tests were performed at eight locations in the project corridor and used as the basis for the vibration prediction model. Therefore, it is appropriate to apply the Detailed Assessment criteria to more accurately identify potential vibration impacts.

The key thresholds applicable to the Tempe Streetcar are a maximum vibration level of 72 VdB for Category 2 (residential) land uses and 78 VdB for Category 3 (institutional) land uses. The thresholds apply to 1/3 octave frequencies on the range of 8 to 80 Hz. This means that for residential land uses, an impact would occur if any 1/3 octave band level between 8 and 80 Hz is predicted to exceed 72 VdB. (Note that there are no vibration Category 1 properties along the corridor, which would include vibration-sensitive research and manufacturing, hospitals with vibration-sensitive equipment, and university research operations. Results for special buildings—concert halls, theaters, etc.—are shown after the Category 3 results.)

The vibration predictions are presented in Table 18 and Table 19 for Category 2 and Category 3 land uses, respectively. The data presented in the tables include:

• ID: Identification number. The location of each sensitive receiver cluster is presented in the maps in Appendix F.

• Desc: Describes the type of land use or name of the receiver.

• Near Track Dist: Distance in feet from the near track centerline to the facade of the closest vibration sensitive building. This is the primary dependent variable in predicted streetcar vibration level since the speed is assumed to be constant and an average LSTM curve is applied to all sensitive receivers.

• Max Band (Hz): The 1/3 octave band corresponding to the maximum 1/3 octave vibration level.

• Max Lv (VdB): The predicted level of Streetcar vibration. These predictions are a single value representing the 1/3 octave band maximum level vibration level. This value is compared to the FTA Detailed Assessment criteria to determine impact.


• Detail Assess Impact?: Whether the spectrum of the predicted vibration exceeds the applicable Detailed Assessment criterion curve.

• # of Units: The number of dwelling units within a listed sensitive receiver where the predicted levels of streetcar vibration exceed the applicable impact threshold.

As shown in Table 18, vibration impact is predicted at two sensitive receivers in Category 2: R6 and R7. Receiver R6 is the University Inn and Suites (five units impacted), and Receiver R7 is the adjacent multi-family residence (one or more units impacted – exact number of units is unknown). Receivers R6 and R7 are within 100 feet of the special trackwork on Mill Avenue between 9th Street and 10th Street. Special trackwork can cause vibration levels to increase by 10 decibels.

As shown in Table 19, no vibration impact is predicted at Category 3 land uses.

Table 20 presents the predicted levels for the sensitive receivers in the “special buildings” category. As discussed in Section 5.3, “special buildings” are assessed for both groundborne vibration and groundborne noise impact. “Special buildings” include the Gammage Auditorium, the ASU Music Hall, and the Valley Art Theater. No groundborne noise or groundborne vibration impact is identified at any of the “special buildings”. Note: For the Valley Art Theater, predictions do not include the building response as the vibration propagates from the façade to the screening room (could not gain access to do related measurements); as mentioned in Section 6.2.7, indoor measurements during final design could clarify whether or not the building response would change the predicted vibration levels.

Note that historic structures that do not fall into the FTA land use categories are not included in the assessment for vibration impact from streetcar operations. The vibration impact thresholds are based on annoyance, and the primary concern for historic structures is the risk of damage. The recommended limit in the FTA guidance manual for buildings extremely susceptible to damage is 90 VdB, which is 18 decibels higher than the limit for Category 2 (residential) land uses. Vibration from streetcar operations will be well below the limit for buildings extremely susceptible to damage at all historic resources.

TABLE 18: SUMMARY OF VIBRATION IMPACT ASSESSMENT FOR CATEGORY 2



Speed

(mph) Max

Band (Hz)

Max Lv

(VdB)

Impact Thresh. (VdB)

Detail Assess. Impact?

# Unitsb

R1 MFR 75 Bridgeview Condos E Rio Salado Pkwy 25 40 61 72 - -

R2 MFR 222 Hayden Condos

154 W 5th St 25 25 49 72 - - R3 Hotel 59 Courtyard Hotel 25 40 65 72 - -




Speed

(mph) Max

Band (Hz)

Max Lv

(VdB)



# Unitsb

R4 MFR 196 111 6th St Condos 25 25 50 72 - -

R5 MFR 198 Encore on Farmer

Senior Housing 25 25 50 72 - - R6 Hotel 51 University Inn & Suites 25 40 77** 72 Y 5 R7 MFR 66 918 S Mill Ave 25 40 73** 72 Y 1+ R8 SFR 70 1100 S Mill Ave 25 40 62 72 - - R9 SFR 68 1104 S Mill Ave 25 40 63 72 - -

R10 SFR 70 1110 S Mill Ave 25 40 62 72 - - R10A SFR 71 1112 S Mill Ave 25 40 62 72 - - R11 SFR 83 1160 S Mill Ave 25 40 60 72 - - R12 SFR 95 1170 S Mill Ave 25 40 58 72 - - R13 SFR 107 1190 S Mill Ave 25 25 56 72 - - R14 SFR 155 1202 S Mill Ave 25 25 53 72 - - R15 SFR 182 1204 S Mill Ave 25 25 51 72 - - R16 SFR 219 1208 S Mill Ave 25 25 49 72 - - R17 SFR 210 21 E 13th St 25 25 50 72 - - R18 SFR 173 25 E 13th St 25 25 51 72 - - R19 SFR 142 33 E 13th St 25 25 53 72 - - R20 Hotel 128 Graduate Hotel 25 25 54 72 - -

R21 MFR 88 ASU Residence Halls

Hayden 25 40 59 72 - -

R22 MFR 50 ASU Student Housing Villas at Vista Del Sol 25 40 68 72 - -

R23 MFR 70

ASU Student Housing Vista Del Sol Towers I,

J, and K 25 40 62 72 - -

R24 MFR 61 ASU Student Housing

Adelphi Commons 25 40 65 72 - -

R25 MFR 58

ASU Residence Halls Chuparosa, Jojoba,

Agave, Sage, Cereus, Cottonwood, Juniper 25 40 65 72 - -

R26 MFR 43 922 E Apache Blvd 25 40 70 72 - - R27 MFR 48 977 E Apache Blvd 25 40 68 72 - - R28 Hotel 66 Super 8 Hotel 25 40 63 72 - - R29 Hotel 87 Holiday Inn Express 25 40 59 72 - - R30 MFR 68 1123 E Apache Blvd 25 40 63 72 - - R33 MFR 55*** Sunset Villas Apts 25 40 66*** 72 - - R34 Hotel 175 Tempe Mission Palms 25 25 51 72 - - R35 SFR 220 S Maple Avenue Homes 25 25 49 72 - - R36 MFR 44 Lennar Development 25 40 70 72 - -

Notes: a. Desc.=Type of land use, SFR=single-family residence, MFR=multi-family residence.


b. Number of impacted units. Note that only units that are within the impact distance and where people sleep are counted for the vibration impacts.

* R31 and R32 are not listed in this table; the Sonoran Ridge Apartments (R31) and Days Inn (R32) are replaced with the Lennar Development (R36). ** The predicted vibration includes +10 dB for amplification from special trackwork. *** 55 ft assumes a worst case scenario where the night-time movement of Streetcars onto the LRT alignment

requires the trains to be passing R33 (although not likely, 25 mph is assumed as a highest vibration level scenario). The other vibration potentially affecting the receiver is from the special trackwork at the Apache terminus; the trackwork is located about 140 ft away from the receiver, and associated maximum vibration levels are lower than from the operations 55 ft away. Note that the sensitive receiver diagrams are provided in Appendix F.

TABLE 19: SUMMARY OF VIBRATION IMPACT ASSESSMENT FOR CATEGORY 3



Speed

(mph) Max

Band (Hz)

Max Lv

(VdB)



# Unitsb

I2 SC 40 Brickyard Engr. Bldg.

699 S Mill Ave 25 40 71 78 - -

I3 80 Tempe Post Office

500 S Mill Ave 25 40 60 78 - -

I4 SC 81

ASU building (use unknown, previously Ceramic Research

Center) 10th and Mill 25 40 70c 78 - -

I5 CH 57

Hillel Jewish Student Center

1012 S Mill Ave 25 40 76c 78 - -

I6 SC 69

Alleluia Lutheran Student School 1034 S Mill Ave 25 40 63 78 - -

I9 CH 110

7th Day Adventist Church

41 E 13th St 25 25 56 78 - -

I10 CH 170 Ten40 Church

1040 E Apache Blvd 25 25 52 78 - -

I11 SC 98

Southwest Institute of Healing Arts (school) 1100 E Apache Blvd 25 40 57 78 - -

I12 SC 163

Southwest Institute of Natural Aesthetics

(school) 1112 E Apache Blvd 25 25 52 78 - -

I13 SC 130

New School for the Arts and Academics

2016 E Apache Blvd 25 25 54 78 - - Notes: a. Desc.=Type of land use, SFR=single-family residence, MFR=multi-family residence. b. Number of impacted units. c. The predicted vibration levels include an adjustment of +10 dB to account for amplification from special trackwork.


* There is no I7 listed in this table; this identification was previously assigned to Chabad at ASU, which appears to now be located farther from the alignment. The sensitive receiver is now a residential land use, listed as receiver R10A in Category 2.

TABLE 20: SUMMARY OF VIBRATION IMPACT ASSESSMENT FOR SPECIAL BUILDINGS

Desc.a Near Track Dist. b

(ft)

Speed

(mph)

FTA Impact Criteria

Predicted Vibration

Vibration Impact

GBV c GBN c GBV c GBN c GBV c GBN c Valley Art Theater 80d 25 72 35 65 32 No No

ASU Music Building (Jazz Rehearsal Hall) 95 25 65 25 53 17 No No ASU Music Building

(W230 Electronic Music Studio No. 1) 95 25 65 25 50 24 No No

Gammage Auditorium 255 25 65 25 48 13 No No Notes: a. Desc.= Name of receiver. b. Distance to the near track is rounded off to the nearest 5 ft. c. GBV = Groundborne vibration, GBN = Groundborne noise. d. Distance from the track centerline to the seating area of the building. Note that the criterion for the "Special Buildings" apply to the screening area and not to the lobby and concession stands.

7.4 OPERATIONAL NOISE MITIGATION

All of the sensitive receivers where noise impact from streetcar operations is predicted are located near the curve as the tracks transition from Mill Avenue onto Apache Boulevard. Predicted streetcar noise levels are higher at sensitive receivers located near a curve because wheel squeal often occurs on curves and can increase noise levels by as much as 10 decibels. To mitigate noise impacts from streetcar operations friction control would be included in the design to help reduce the occurrence of wheel squeal. Two approaches to friction control are (1) applying a friction modifier to the rail head and/or the wheel tread, or (2) applying lubricant to the gauge face of the rail or the wheel flange. Including friction control at the curve at Mill Avenue and Apache Boulevard would reduce predicted noise levels to below the moderate impact threshold.

Noise impact is also predicted at one location, R35, adjacent to the U/M TPSS site; R35 is a group of 4 single-family residences. To mitigate the noise impact from the TPSS unit, the TPSS unit would be strategically located within the site, with the major noise source, the cooling fans, being as far from the residences as possible. If the TPSS unit is located within the parcel as far as feasible and oriented with the cooling fans facing away from the sensitive receivers, the predicted noise level could be reduced to below the applicable threshold. The cooling fans on the TPSS unit should be facing toward Mill


Avenue and located more than 50 feet from the nearest residence to reduce the predicted noise levels to below the impact threshold. If there is not much flexibility on where to locate the unit within the parcel, a sound enclosure would be built around the TPSS unit to reduce noise levels at sensitive receivers.

Noise mitigation measures should be reviewed and finalized in the final design phase of the project.

7.5 OPERATIONAL VIBRATION MITIGATION

All of the sensitive receivers where vibration impact is predicted are located near special trackwork. The gaps in the rail associated with typical special trackwork can cause vibration levels to increase by up to 10 decibels. To mitigate for operational vibration, low-impact frogs would be installed at the special trackwork near vibration-sensitive receivers. Low impact frogs can reduce vibration levels by creating a smoother transition through the gap in the rails at the special trackwork. Examples of low-impact frogs include monoblock frogs or flange-bearing frogs. If a flange-bearing frog is used, the recommended length of the ramp in the frog is a minimum of two-feet. Installing low-impact frogs would reduce the predicted vibration levels to below the FTA impact threshold at all sensitive receivers. A summary of the mitigation is presented in Table 21.

Vibration mitigation measures should be reviewed and finalized in the final design phase of the project.

TABLE 21: SUMMARY OF VIBRATION MITIGATION

ID Location Number of Units Impacted Before

Mitigation Mitigation

R6 Between 9th St. and 10th St. on

Mill Ave.

3 Low-impact frogs for special trackwork on Mill

Avenue between 9th Street and 10th Street R7 1


8.0 POTENTIAL CONSTRUCTION NOISE AND VIBRATION IMPACTS AND MITIGATION

8.1 CONSTRUCTION NOISE

The use of heavy equipment during project construction has the potential to result in substantial, yet temporary, increases in local noise levels along the corridor. The FTA Guidance Manual recommends using local construction noise limits, if possible. The noise ordinance of the City of Tempe restricts the hours of operation for construction, demolition or excavation equipment within a residential zone or any property within a radius of 500 feet of a residential zone. The limits on construction noise in the ordinance are:

• Allowed construction hours from April 15 to October 15 inclusive: 5 AM to 7 PM. • Allowed construction hours during weekdays of the remaining months of the

year: 6 AM to 7 PM. • Allowed construction hours during weekends and legal holidays throughout the

year: 7 AM to 7 PM.

Restricted permits for regular or emergency construction during prohibited hours may be obtained from the City Manager or his authorized representative of the City of Tempe. The City Manager will determine if construction during the prohibited hours would be less objectionable to the neighborhood and less interfering to traffic before issuing a permit.

The City of Tempe noise ordinance does not provide limits that can be used to define an impact threshold. While the FTA Guidance Manual does not include any standardized limits for construction noise levels; FTA does provide the guidelines shown in Table 22 for evaluating the potential community response to construction noise. The guidelines are based on an average Leq over a typical 8-hour workday. The FTA recommended limit of 80 dBA for the daytime Leq has been used in this assessment as the threshold for impact for residential areas.

TABLE 22: CONSTRUCTION NOISE GUIDELINES

Land Use Noise Limit,

8 hr Leq (dBA) Daytime Nighttime

Residential 80 70 Commercial 85 85

Industrial 90 90 Source: FTA (2006) Ref 1


Construction noise levels depend on the number of pieces and type of equipment, their general condition, the amount of time each piece operates per day, the presence or lack of noise attenuating features such as walls and berms, and the location of the construction activities relative to the sensitive receivers. The majority of these variables are left to the discretion of the construction contractor. Therefore, it is not possible to accurately estimate construction noise levels at this stage of the project.

The construction of streetcar track requires use of heavy earth-moving equipment, pneumatic tools, generators, concrete pumps, and similar equipment. Table 23 shows the equipment likely to be used during the noisiest periods of track construction, the typical noise generated by this equipment, the usage factors, and the estimated work-shift Leq. The combined work-shift Leq for the construction scenario shown in Table 23 is 84 dBA at a distance of 50 feet. Given that residences along the corridor are often within 50 ft of the alignment, it is clear that there is a high probability that the contractor would exceed the impact threshold of 80 dBA for the work-shift Leq. This analysis shows that impacts are likely unless the contractor is required to implement noise control measures when working near residences.

TABLE 23: PREDICTED CONSTRUCTION NOISE

Equipment Sound Level @ 50 ft under Load

Source Usage Factor (% Time

Under Full Load) Leq (8hr Work

Shift)

Earthmover (bulldozer, front-end loader, etc.) 82 dBA 40% 78 dBA

Mobile Crane 81 dBA 20% 74 dBA Dump Truck 76 dBA 40% 72 dBA Pneumatic Tools 85 dBA 30% 80 dBA Generator 78 dBA 40% 74 dBA Compressor 81 dBA 40% 77 dBA TOTAL 84 dBA

8.2 CONSTRUCTION VIBRATION

The primary concern regarding construction vibration is potential damage to structures. The thresholds for potential damage are much higher than the thresholds for evaluating potential annoyance used to assess impact from operational vibration. The FTA Guidance Manual limits for construction vibration are shown in Table 24. It is important to note that the vibration limits in Table 24 are the levels at which there is a risk for damage for each building category, not the level at which damage would occur. These limits should be viewed as criteria that should be used during the impact assessment phase to identify problem locations that must be addressed during final design.


Predicted vibration levels for different pieces of construction equipment are shown in Table 25. At a distance of 50 feet from buildings, the predicted vibration level for all pieces of equipment is below the damage risk criteria for even those buildings most susceptible to damage. At a distance of 25 feet, the vibration level from a vibratory roller is predicted to exceed the damage criteria for Building Categories III and IV.

Vibration generated from the vibratory roller could result in an adverse effect if it is operated within 25 feet of non-engineered timber or masonry buildings. Mitigation measures for construction vibration are presented in Section 8.4. In the event that other vibration generating equipment needs to be used for a sustained period of time closer than 25 feet to sensitive receivers the Construction Management Plan should also include measures to minimize those potential vibration impacts during construction.

An historic adobe structure, the Hayden House (most recently known as Monti’s La Casa Vieja), is located at the corner of Rio Salado Parkway and Mill Avenue, about 50 feet from the proposed streetcar tracks. As discussed above, predicted vibration levels from construction equipment do not exceed the construction vibration limit for buildings extremely susceptible to damage at 50 feet. No adverse effect from construction vibration is predicted for the Hayden House. Although no adverse effect is predicted, the Hayden House would be included as part of the Pre-Construction Survey to document existing conditions.

TABLE 24: CONSTRUCTION VIBRATION DAMAGE RISK CRITERIA Building Category Peak Particle

Velocity (in/sec) I. Reinforced-concrete, steel or timber (no plaster) 0.5

II. Engineered concrete and masonry (no plaster) 0.3

III. Non-engineered timber and masonry buildings 0.2

IV. Buildings extremely susceptible to vibration damage 0.12

Source: FTA (2006)

TABLE 25: CONSTRUCTION VIBRATION PREDICTIONS Equipment PPV at 25 ft (in/sec) PPV at 50 ft (in/sec)

Vibratory Roller 0.21 0.07 Hoe Ram 0.09 0.03

Large Bulldozer 0.09 0.03 Caisson Drilling 0.09 0.03 Loaded Trucks 0.08 0.03


Equipment PPV at 25 ft (in/sec) PPV at 50 ft (in/sec) Jackhammer 0.04 0.01

Small Bulldozer 0.003 0.001

8.3 CONSTRUCTION NOISE MITIGATION

Listed below are some typical approaches to reducing noise levels associated with the construction phase of major projects. Requiring the contractor to employ these methods should leave the contractor with enough flexibility to perform the work without undue financial or logistical burdens while protecting adjacent noise sensitive receivers from excessive construction noise levels.

• Avoid nighttime construction unless a variance is issued by the City. This is a requirement of the City of Tempe noise ordinance.

• Use specialty equipment with enclosed engines and/or high-performance mufflers.

• Locate equipment and staging areas as far from noise-sensitive receivers as possible.

• Limit unnecessary idling of equipment.

• Install temporary noise barriers. This approach can be particularly effective for stationary noise sources such as compressors and generators.

• Reroute construction related truck traffic away from local residential streets.

• Avoid impact pile driving where possible. Where geological conditions permit, the use of drilled piles or a vibratory pile driver is generally quieter.

Specific measures to be employed to mitigate construction noise impacts would be developed by the contractor and presented in the form of a Noise Control Plan.

8.4 CONSTRUCTION VIBRATION MITIGATION

Construction related vibration activities are unlikely to exceed the impact thresholds shown in Table 24. However, the following precautionary vibration mitigation strategies would be implemented to minimize the potential for damage to any structures in the corridor:

• Pre-Construction Survey: The survey should include inspection of building foundations and taking photographs of pre-existing conditions. The survey can be limited to buildings within 25 feet of high-vibration generating construction activities. The only exception is if an important and potentially fragile historic


resource is located within approximately 200 feet of construction, in which case it should be included in the survey.

• Vibration Limits: The FTA guidance manual (Ref. 1) suggests vibration limits in terms of peak particle velocity (PPV) ranging from 0.12 in/sec for “buildings extremely susceptible to vibration damage” to 0.5 in/sec for “Reinforced-concrete, steel or timber” buildings. The contract specifications should limit construction vibration to a maximum of 0.5 in/sec for all buildings in the corridor. Should the pre-construction survey identify any buildings that are particularly sensitive to vibration, such as the Hayden House, the vibration at these structures should be limited to 0.12 in/sec.

• Vibration Monitoring: The contractor should be required to monitor vibration at any buildings where vibratory rollers or similar high vibration-generating equipment would be operated within 25 feet of buildings and at any location where complaints about vibration are received from building occupants.

• Alternative Construction Procedures: If high-vibration construction activities would be performed close to structures, it may be necessary for the contractor to use an alternative procedure that produces lower vibration levels. Examples of high-vibration construction activities include the use of vibratory compaction or hoe rams next to sensitive buildings. Alternative procedures include use of non-vibratory compaction in limited areas and a concrete saw in place of a hoe ram to breakup pavement.


9.0 REFERENCES References:

1. Federal Transit Administration Office of Planning and Environment (FTA0. 2006. Transit Noise and Vibration Impact Assessment. Document FTA-VA-90-1003-06, May.


APPENDIX A FUNDAMENTALS OF NOISE AND VIBRATION

A.1. NOISE FUNDAMENTALS

Sound is mechanical energy transmitted by pressure waves in a compressible medium such as air. Typically, noise is defined as unwanted or excessive sound. Sound can vary in intensity by over one million times within the range of human hearing. Therefore, a logarithmic scale, known as the decibel scale (dB), is used to quantify sound intensity and compress the scale to a more convenient range.

Sound is characterized by both its amplitude and frequency (or pitch). The human ear does not hear all frequencies equally. In particular, the ear deemphasizes low and very high frequencies. The A-weighted decibel scale (dBA) better approximates the sensitivity of human hearing. On this scale, the human range of hearing extends from approximately 3 dBA to around 140 dBA. As a point of reference, Figure 12 includes examples of A-weighted sound levels from common indoor and outdoor sounds.

Using the decibel scale, sound levels from two or more sources cannot be directly added together to determine the overall sound level. Rather, the combination of two sounds at the same level yields an increase of 3 dB. The smallest recognizable change in sound level is approximately 1 dB. A 3 dB increase in the A-weighted sound level is considered generally perceptible, whereas a 5 dB increase is readily perceptible. A 10 dB increase is judged by most people as an approximate doubling of the perceived loudness.

The two primary factors that reduce levels of environmental sounds are (1) increasing the distance between the sound source and the receiver and (2) having intervening obstacles such as walls, buildings, or terrain features that block the direct path between the sound source and the receiver. Factors that act to make environmental sounds louder include moving the sound source closer to the receiver, sound enhancements caused by reflections, and focusing caused by various meteorological conditions.

The following are brief definitions of the measures of environmental noise used in this report:

Maximum Sound Level (Lmax): Lmax is the maximum sound level that occurs during an event such as a streetcar passing. For this analysis, Lmax is defined as the maximum sound level using the slow setting on a standard sound level meter.

Equivalent Sound Level (Leq): Environment sound fluctuates constantly. The equivalent sound level (Leq) is the most common means of characterizing community Noise and Vibration Technical Report Page 71 May 2015 Environmental Assessment Tempe Streetcar

noise. Leq represents a constant sound that, over a specified period of time, has the same sound energy as the time-varying sound. Leq is used by FTA to evaluate noise impacts at institutional land uses, such as schools, churches, and libraries, from proposed transit projects.

Day-Night Sound Level (Ldn): Ldn is a 24-hour Leq with an adjustment to reflect the greater sensitivity of most people to nighttime noise. The adjustment is a 10 dB penalty for all sound that occurs between the hours of 10:00 PM to 7:00 AM. The effect of the penalty is that, when calculating Ldn, any event that occurs during the nighttime is equivalent to ten occurrences of the same event during the daytime. Ldn is the most common measure of total community noise over a 24-hour period and is used by FTA to evaluate residential noise impacts from proposed transit projects.

Lxx: This is the percent of time a sound level is exceeded during the measurement period. For example, the L99 is the sound level exceeded 99 percent of the measurement period. For a one hour period, L99 is the sound level exceeded for all except 36 seconds of the hour. L1 represents typical maximum sound levels, L33 is approximately equal to Leq when free-flowing traffic is the dominant noise source, L50 is the median sound level, and L99 is close to the minimum sound level.

Sound Exposure Level (SEL): SEL is a measure of the acoustic energy of an event such as a train passing. In essence, the acoustic energy of the event is compressed into a one second period. SEL increases as the sound level of the event increases and as the duration of the event increases. It is often used as an intermediate value in calculating overall metrics such as Leq and Ldn.

Sound Transmission Class (STC): STC ratings are used to compare the sound insulating effectiveness of different types of noise barriers, including windows, walls, etc. Although the amount of attenuation varies with frequency, the STC rating provides a rough estimate of the transmission loss from a particular window or wall.


FIGURE 12: TYPICAL OUTDOOR AND INDOOR NOISE LEVEL

A.2. VIBRATION FUNDAMENTALS

One potential community impact from the proposed project is vibration that is transmitted from the tracks through the ground to adjacent houses. This is referred to as groundborne vibration. When evaluating human response, groundborne vibration is expressed in terms of decibels using the root mean square (RMS) vibration velocity. RMS is defined as the average of the squared amplitude of the vibration signal. To avoid confusion with sound decibels, the abbreviation VdB is used for vibration decibels. All vibration decibels in this report use a decibel reference of 1 micro-inch/second (µin/sec.).1

The potential adverse impacts of rail transit groundborne vibration are as follows:

1 One µin/sec= 10 -6 in/sec.


Perceptible Building Vibration: The vibration of the floor or other building surfaces that the occupants feel. Experience shows that the threshold of human perception is around 65 VdB and that vibration that exceeds 75 to 80 VdB is perceived as intrusive and annoying to occupants.

Rattle: The building vibration can cause rattling of items on shelves and hangings on walls, and various rattle and buzzing noises from windows and doors.

Reradiated Noise: The vibration of room surfaces radiates sound waves that are audible to humans (groundborne noise). Groundborne noise sounds like a low-frequency rumble. Usually, for a surface rail system such as the proposed streetcar, the groundborne noise is masked by the normal airborne noise radiated from the transit vehicle and the rails.

Damage to Building Structures: Although it is conceivable that vibration from a streetcar system can damage fragile buildings, the vibration from rail transit systems is one to two orders of magnitude below the most restrictive thresholds for preventing building damage. Hence the vibration impact criteria focus on human annoyance, which occurs at much lower amplitudes than does building damage.

Vibration is an oscillatory motion that is described in terms of the displacement, velocity, or acceleration of the motion. The response of humans to vibration is very complex. However, the general consensus is that for the vibration frequencies generated by streetcars, human response is best approximated by the vibration velocity level. Therefore, this study uses vibration velocity to describe streetcar-generated vibration levels.

Figure 13 shows typical vibration levels from rail and non-rail sources as well as the human and structure response to such levels.

Although there is relatively little research into human and building response to groundborne vibration, there is substantial experience with vibration from rail systems. In general, the collective experience indicates that:

It is rare that groundborne vibration from transit systems results in building damage (even minor cosmetic damage). Therefore, the primary consideration is whether or not the vibration is intrusive to building occupants or interferes with interior activities or machinery.

The threshold for human perception is approximately 65 VdB. Vibration levels in the range of 70 to 75 VdB often are noticeable but acceptable. Beyond 80 VdB, vibration levels are considered unacceptable.


For human annoyance, there is a relationship between the number of daily events and the degree of annoyance caused by groundborne vibration. The FTA Guidance Manual includes an 8 VdB higher impact threshold if there are fewer than 30 events per day and a 3 VdB higher threshold if there are fewer than 70 events per day.

FIGURE 13: TYPICAL VIBRATION LEVELS

Often it is necessary to determine the contribution at different frequencies when evaluating vibration or noise signals. The 1/3-octave band spectrum is the most common procedure used to evaluate frequency components of acoustic signals. The term octave is borrowed from music, where it refers to a span of eight notes. The ratio of the highest frequency to the lowest frequency in an octave is 2:1. For a 1/3-octave band spectrum, each octave is divided into three bands, where the ratio of the lowest frequency to the highest frequency in each 1/3-octave band is 21/3:1 (1.26:1). An octave consists of three 1/3 octaves.

The 1/3-octave band spectrum of a signal is obtained by passing the signal through a bank of filters. Each filter excludes all components except those that are between the upper and lower range of one 1/3-octave band.


APPENDIX B FORCE DENSITY MEASUREMENT RESULTS This appendix provides the results of the streetcar vibration testing that was performed at the South Lake Union (SLU) Streetcar system in Seattle, WA and the Portland, OR streetcar system. Both of these systems are modern streetcars. The equipment (vehicles and track design) that would be used for the Tempe modern streetcar are expected to be similar to the equipment that is in use at the SLU and Portland streetcar systems.

The purpose of the testing in Portland and Seattle was to characterize the vibration forces generated by representative modern streetcar systems. As discussed below, the vibration forces are characterized by the force density level (FDL) that is derived from measurements of streetcar vibration and transfer mobility at an operating streetcar system. The FDL is used as the source vibration for the vibration predictions.

B.1. SEATTLE STREETCAR MEASUREMENTS

FDL measurements were performed in Seattle along the South Lake Union Streetcar alignment on July 22, 2011. The test was performed at a section east of the South Lake Union Park Station on Valley Street with two tracks: eastbound (EB) and westbound (WB). Two streetcar vehicles, referred to here as the blue and purple vehicles, were operating on the SLU system during the measurements.

Following is a summary of the tests performed to derive a force density for the Seattle Streetcar:

1. Streetcar vibration was measured at five distances from the track. The accelerometers were placed at distances ranging from 25 to 125 ft north of the WB track, which was the near track (NT). The EB track was 12 ft south of the WB track.

2. The root mean square (rms) streetcar vibration at each measurement position was determined on a 1/3 octave band basis over the frequency range of 5 to 315 Hz. The measured 1/3 octave band rms vibration levels were adjusted to obtain the maximum 1-second rms value for the streetcar vibration.

3. Transfer mobility was measured using a line of impacts. The impact line consisted of 11 locations separated by 15 ft for a total length of 150 ft. The same accelerometer positions used for the train vibration were used for the transfer mobility tests. The impact line was offset from the NT and was 5 ft closer to the accelerometers. The point source transfer mobilities at the 11 impact points were


combined to obtain the line source transfer mobility (LSTM) at each accelerometer position.

4. The FDL from each train passby was calculated as the difference between the measured train vibration level and the LSTM after adjusting the LSTM for the 5 ft offset distance from the WB track and the 17 ft offset from the EB track. The vibration data from frequency bands where the streetcar vibration did not exceed the background vibration was not used in the FDL calculation. Also LSTM data with poor coherence (lower than 0.3) was not used in the FDL calculations. The result was a series of FDL spectra over the 25 to 160 Hz frequency range.

5. At each accelerometer position, the FDL estimates for each vehicle and track were energy averaged.

6. The final FDLs for the two vehicles were estimated by using the maximum of the energy averaged force densities of all sensor positions. This approach was taken to ensure that the final FDLs would be an upper bound of the true FDL and would tend to over predict streetcar vibration levels rather than under predict vibration levels.

FIGURE 14: SLU STREETCAR FORCE DENSITY MEASUREMENT LOCATION


Transfer Mobility Tests

The measured transfer mobility and coherence functions from the propagation tests are given in Figure 15. The transfer mobilities were measured using accelerometers mounted at distances of 25, 50, 75, 100 and 125 ft from the WB track centerline. The impact line was located 5 ft from the track centerline. As expected, the transfer mobilities decreased with distance from the impact line. There was good coherence over the 8 to 125 Hz range at all except the 125 ft measurement position. The transfer mobility at 125 ft had poor coherence above 80 Hz.

FIGURE 15: LSTM AND COHERENCE, SEATTLE SOUTH LAKE UNION PARK

Streetcar Vibration

Streetcar vibration was measured at the same locations as the transfer mobility measurements. There were two tracks at the measurement location. The WB track was the NT and the EB track centerline was 12 ft from the WB track centerline. As discussed earlier, the vibration sensors were located at 25, 50, 75, 100 and 125 ft from the WB track centerline and were identified as Channels 2, 3, 4, 5, and 6, respectively.

During the measurement period, there were three blue car passbys on the WB track, five blue car passbys on the EB track, and four purple car passbys on the EB and WB tracks. The streetcar speeds were measured with a radar gun and ranged from 12 to 16 mph. The measurement results are shown in Figure 16 through Figure 21. Observations from the streetcar vibration results are:

1. Below 25 Hz and above 160 Hz the streetcar vibration did not exceed the background vibration. Therefore, this frequency range was excluded from the FDL calculation.


2. At the 125 ft position (Channel 6), the streetcar vibration had attenuated enough that it did not exceed the background vibration at any frequencies (see Figure 20). Therefore the data from this measurement position were not used in the FDL calculation.

3. Blue car passby T2 on the WB track had unusually high vibration and appears to have been corrupted by vibration from another source. The results for T2 were excluded from the averages.

4. Vibration levels from the purple car were consistently 5 to 10 decibels in the 80 and 100 Hz 1/3 octave bands compared to the blue car. The differences occurred at all of the measurement positions where streetcar vibration exceeded the background vibration. The differences are most distinct in the results at the 25 ft measurement position (see Figure 16).

FIGURE 16: MEASURED TRAIN VIBRATION AT 25 FEET FROM NT


FIGURE 21: AVERAGE SEATTLE STREETCAR VIBRATION


Force Density

Figure 22 shows the average FDL from each measurement position for the blue and purple cars on the WB and EB tracks. The maximum spectra on 1/3 octave band basis of these average FDLs are shown in Figure 23. From Figure 23 it is clear that the FDL for the purple car has peaks at 80 and 100 Hz that do not appear in the blue car FDL. The peaks at 80 and 100 Hz correspond to a surface corrugation with a wavelength of approximately 2.5 inches. Because the blue and purple vehicles were similar and the track conditions were comparable, it is reasonable to infer that the purple train FDL peaks were caused by a sub-optimal wheel surface on the purple vehicle with wavelength of approximately 2.5 inches.

FIGURE 22: AVERAGE SLU STREETCAR FORCE DENSITY LEVELS


FIGURE 23: SLU STREETCAR FORCE DENSITY LEVEL

FIGURE 24: SLU STREETCAR FDL FOR PREDICTIONS FDLs adjusted to a speed of 25 mph


B.2. PORTLAND STREETCAR MEASUREMENTS

Force density measurements were performed on the Portland Streetcar alignment at three sites:

• Site A – Northrup in 2007 • Site B – Riverarea in 2007 • Site C – South Waterfront in 2011

The FDL measurement locations on the streetcar alignment are shown in Figure 25. The details of the measurements performed at Sites A and B were documented in the Noise and Vibration Technical Report prepared for the environmental assessment of the Tucson Streetcar project.2

FDL Measurements at Site C

Force density measurements at Site C along the Portland Streetcar alignment was performed on July 28, 2011. The measurement was performed at Caruthers Park on Bond Street between Curry Street and Gaines Street. This section of the streetcar alignment has one track and the streetcar speed during the measurements ranged from 10 to 15 mph.

Vibration propagation tests were performed at this site with the impact line located at track centerline. The impacts were performed at 11 locations separated by 15 ft for a total impact line length of 150 ft. The sensors were placed at 25, 37.5, 50, 75, 100 and 150 ft from the track centerline and were identified as Channel 2, 3, 4, 5, 6 and 7, respectively. The measured LSTM and coherence curves are shown in Figure 26. The LSTM attenuated with distance as expected. The measured data showed good coherence between 8 and 125 Hz for all measurement positions. The coherence drops rapidly at higher and lower frequencies.

Streetcar vibration was measured for 10 passbys. During three of the passbys the streetcars stopped near the measurement location. These measurements were excluded from the analysis. Because of an equipment problem, streetcar vibration was recorded only on Channels 5, 6 and 7. The streetcar vibration data at Channels 5 and 6 are shown in Figure 28. The streetcar vibration levels were above the background vibration between 25 and 125 Hz. For Channel 7, the streetcar vibration was always

2 Appendix E, Tucson Urban Corridor Environmental Assessment and Section 4(f) Evaluation, January 18, 2008.


less than the background vibration. Therefore the Channel 7 data could not be used to help estimate FDL.

The FDL results from Site C in Portland are shown Figure 29. As shown in Figure 29, the FDL at Site C showed a peak at 100 Hz. The FDL from the three different tests in Portland are shown in Figure 30. As can be seen there is a wide variation in the FDL, particularly in the 63 to 125 frequency range. The strong peak at 100 Hz for the Site B FDL did not appear at the other two sites, which indicates that the peak is probably something related to the track at Site B. The most likely cause of this peak is a corrugation wavelength in the rail of approximately 2 inches. Unfortunately, rail roughness was not measured when the FDL measurement was performed in 2007 at Site B so the source of the peak at 100 Hz cannot be confirmed.


FIGURE 25: MAP OF PORTLAND STREETCAR FDL SITES A, B AND C


FIGURE 26: PORTLAND STREETCAR FORCE DENSITY MEASUREMENT SITE C

FIGURE 27: LSTM AND COHERENCE, PORTLAND SITE C


FIGURE 28: MEASURED STREETCAR VIBRATION AT SITE C IN PORTLAND

FIGURE 29: PORTLAND STREETCAR FDL AT SITE C (2011)


FIGURE 30: COMPARISON OF PORTLAND STREETCAR FDL (Levels have been adjusted to a speed of 25 mph assuming a speed

dependence of 20*log(speed))

B.3. RAIL ROUGHNESS MEASUREMENTS

The wheel and rail surfaces are never completely and their unevenness causes the rail and wheel to move relative of each other causing acoustic excitation. Roughness is the term used to refer to these surface unevenness. The frequency of acoustic excitation created by rail roughness depends on the wavelength of roughness and the streetcar speed. Depending on the frequency of excitation, the problems can occur either in the noise or vibration regime. This relationship is shown here:

𝑓𝑓𝑜𝑜𝐿𝐿𝐿𝐿𝑜𝑜𝐿𝐿𝐿𝐿𝑓𝑓𝑓𝑓 =𝑣𝑣𝐿𝐿𝑣𝑣𝑜𝑜𝑓𝑓𝐷𝐷𝐷𝐷𝑓𝑓

𝑤𝑤𝑤𝑤𝑣𝑣𝐿𝐿𝑣𝑣𝐿𝐿𝐿𝐿𝑤𝑤𝐷𝐷ℎ

In the above equation, wavelength is the length of roughness on the rail or wheel. For streetcars traveling at 15 mph, 2 inch (50.8 mm) roughness wavelength translates to excitation at about 130 Hz. Longer wavelengths lead to lower frequency excitation, and higher speeds will cause higher frequency excitation.

The rail roughness was measured on the westbound track of the Seattle Streetcar and the single Portland Streetcar track at Site C during the force density measurements.

The results of the measurements are provided in Figure 33. The roughness levels are represented in decibels with reference to 1 µin and plotted against the wavelength of the rail roughness expressed in mm. The roughness levels are compared with the rail Noise and Vibration Technical Report Page 92 May 2015 Environmental Assessment Tempe Streetcar

roughness spectrum recommended by ISO 3095.3 Rails with roughness levels exceeding the ISO recommended levels are expected to result in higher acoustic excitation. If the speeds are low enough or the length of the track surface deformation is high enough to cause vibration excitation, the vibration levels from train passbys can be expected to be higher than on rails with optimal profiles.

Figure 31 and Figure 32 are photographs taken during the roughness measurements in Portland. The results of the roughness measurements in Seattle and Portland are in Figure 33. The key points from the roughness measurements shown Figure 33 in are:

• The roughness results in Portland and Seattle are remarkably similar. • The rail roughness at both Portland and Seattle were higher than the ISO 3095

standard across the spectrum. • Because the roughness spectrum did not show any peaks, the acoustic

excitation from the rough rail surface can be expected to be a broadband excitation.

• There is potential for reducing the streetcar noise and vibration for the Tempe Streetcar project by implementing a track maintenance program that maintains the rail roughness to levels below the ISO 3095 standard. It is noteworthy that rail smoothness needs to be accompanied with optimal wheel surface to minimize noise and vibration excitation.

3 ISO 3095, Second edition, 2005-08-15, “Railway applications - Acoustics - Measurement of noise emitted by railbound vehicles, Annex A, Rail roughness measurement specifications.”


FIGURE 31: RAIL ROUGHNESS MEASUREMENTS IN PORTLAND FDL SITE C

FIGURE 32: RAIL CONDITION IN PORTLAND

FIGURE 33: RAIL ROUGHNESS MEASUREMENT RESULTS Seattle WB, NR: Westbound track, north rail Seattle WB, SR: Westbound track, south rail


Portland NB, ER: Northbound track, east rail Portland NB, WR: Northbound track, west rail ISO 3095: Recommended roughness limit

B.4. FORCE DENSITY CALCULATIONS

The measured streetcar FDL for two different streetcar vehicles in Seattle and three different sites in Portland are shown in Figure 34. The key points from the streetcar FDL measurements are:

• Both in Seattle and Portland similar vehicles provided very different FDL spectrum indicating potential variations in the wheel-rail interface.

• The streetcar FDL varied widely between 40 and 125 Hz. Much of this variation is likely to be due to rail corrugation at one site in Portland and problems with the wheels for one of the Seattle vehicles.

• Because the rail roughness did not show dominant unevenness at any particular frequency, the difference in FDL between the purple and blue vehicles in Seattle is most likely due to problems with the wheels of the purple vehicle.

• It is feasible to keep the FDL at a minimum level between 40 and 125 Hz through the maintenance of an optimal wheel-rail interface.

A composite streetcar FDL was derived by combining the Seattle blue car FDL between 25 and 125 Hz with the highest available FDL outside this frequency range. It is


noteworthy that the blue car FDL was selected over the Site A measurements from Portland as the baseline FDL between 25 and 125 Hz because detailed data was available for the measurements in Seattle. For Site A in Portland no rail roughness data was available.

FIGURE 34: MEASURED STREETCAR FDL


APPENDIX C STREETCAR NOISE MEASUREMENT RESULTS Both streetcar noise and LRT noise measurements are described below. The streetcar measurements are discussed and shown for reference only (in case actual low-speed streetcar spectra are of use in future analyses). These below 20 mph data were not used in the Tempe Streetcar noise predictions; instead, Phoenix LRT Starter Line data were used for the Tempe Streetcar predictions, explained in the following paragraphs.

Streetcar noise measurements were performed in Portland at the Caruthers Park (Site C) during the force density measurements. The microphone was located 50 ft from the track centerline. A total of 10 streetcar passbys were recorded and two of the passbys were removed from the analysis due to interference from background noise. The streetcar speeds ranged from 10 to 15 mph and during two of the passbys the streetcars with approximately 10 mph stopped and accelerated near the measurement location. The measured A-weighted maximum sound level is shown in Figure 35. The A-weighted spectrum shows that the streetcar sound spectrum was independent of speed and except for the trains that stopped the levels were comparable for all speeds. There was a peak at 4000 Hz for all passbys. Because the rail roughness measurements did not show any unusual characteristics corresponding to 4000 Hz, the noise peaks are inferred to be an attribute of the streetcar vehicles.

The general trend for train noise is that at speeds below 20 mph the vehicle transmission noise dominates and is independent of speed. Above 20 mph, the rolling noise due to metal to metal contact at the wheel-rail interface dominates. As a result, extrapolating the noise measurements performed at speeds below 15 mph to streetcar speeds of 25 mph would likely over-predict the streetcar noise. Therefore, for the Tempe Streetcar noise analysis the Lmax measurements performed on the Phoenix Metro Starter Line (LRT embedded track) was used as the reference noise. This approach was taken because the proposed operating speed for the Tempe Streetcar is 25 mph and for a given speed the LRT noise from an embedded track would be comparable to the streetcars. The noise measurements from the Phoenix Metro (LRT) Starter Line are documented in the Noise and Vibration Appendix of the Final Environmental Assessment for the Central Mesa LRT Extension, May 2011.


FIGURE 35: MEASURED STREETCAR NOISE LEVEL AT PORTLAND SITE C


APPENDIX D VIBRATION PROPAGATION TEST RESULTS This section provides photos of the vibration propagation test sites, measured line source transfer mobility (LSTM) and coherence at each site, and the best fit coefficients derived from the measured LSTM at each site. Photos of the vibration propagation sites are shown in Figure 36 through Figure 47, in Section D.1.

Aerial diagrams of the vibration propagation sites are shown in Figure 48 through Figure 55 in Section D.2.

The measured LSTM and coherence are shown in Figure 56 through Figure 63, in Section D.3.

The table of coefficients for the best fit curves are shown in Table 26 through Table 33, in Section D.4.


D.1. PHOTOS OF VIBRATION PROPAGATION SITES

FIGURE 36: VIBRATION PROPAGATION SITE V-3




FIGURE 39: FIRST FLOOR INDOOR SENSOR AT SITE V-5


FIGURE 40: SECOND FLOOR INDOOR SENSOR AT SITE V-5




FIGURE 45: VIBRATION PROPAGATION SITE V-13, INDOOR SENSORS


FIGURE 47: VIBRATION PROPAGATION SITE V-14, INDOOR SENSORS


D.2. TEST DIAGRAMS OF VIBRATION SITES

Provided in this section are diagrams of the vibration propagation test at each site. The yellow Xs indicated where the drop-weight hit the ground. The circles with A# in them indicate where vibration sensors (accelerometers) were placed. The solid yellow lines indicate the imaginary impact line and line of accelerometers. The impact line is intended to simulate a line-source train vibration. The line of accelerometers is used to derive the LSTM quantity as a function of distance away from the line-source.

FIGURE 48: AERIAL VIEW OF VIBRATION PROPAGATION SITE V-3


D.3. MEASURED LSTM AND COHERENCES AT EACH SITE

FIGURE 56: MEASURED LSTM AND COHERENCE AT SITE V-3


D.4. LSTM COEFFICIENTS FOR EACH SITE

TABLE 26: LINE SOURCE TRANSFER MOBILITY COEFFICIENTS, SITE V-3 Frequency A B C

6.3 17.2 -9.4 -- 8 25.9 -13.7 -- 10 29.0 -12.9 --

12.5 43.5 -17.3 -- 16 53.2 -19.1 -- 20 72.1 -26.2 -- 25 78.1 -27.5 --

31.5 86.2 -32.3 -- 40 80.3 -30.3 -- 50 67.8 -25.8 -- 63 61.9 -25.2 -- 80 63.9 -29.3 -- 100 61.3 -30.8 -- 125 58.6 -32.3 -- 160 37.5 -25.4 -- 200 21.3 -21.1 -- 250 13.6 -16.6 -- 315 12.8 -16.1 --



6.3 29.0 -16.3 -- 8 25.9 -14.0 -- 10 47.7 -24.7 --

12.5 69.1 -33.1 -- 16 101.7 -47.7 -- 20 75.1 -27.9 -- 25 92.5 -35.9 --

31.5 108.9 -44.3 -- 40 116.8 -49.3 -- 50 77.1 -28.4 -- 63 74.4 -31.4 -- 80 33.0 -8.4 -- 100 40.4 -13.3 -- 125 39.3 -15.4 -- 160 52.2 -26.0 -- 200 51.4 -29.4 -- 250 8.2 -10.5 -- 315 -28.6 8.7 --


6.3 11.1 -5.9 -- 8 9.6 -5.5 -- 10 15.7 -7.2 --

12.5 25.8 -10.7 -- 16 37.4 -13.5 -- 20 38.3 -8.2 -- 25 46.3 -7.0 --

31.5 79.5 -26.5 -- 40 94.7 -36.2 -- 50 91.1 -37.0 -- 63 90.2 -39.7 -- 80 85.6 -40.9 -- 100 79.4 -39.5 -- 125 70.2 -35.7 -- 160 81.4 -45.9 -- 200 74.5 -46.3 -- 250 70.4 -45.4 --


315 62.3 -40.5 --

TABLE 29: LINE SOURCE TRANSFER MOBILITY COEFFICIENTS, SITE V-6

Frequency A B C 6.3 20.9 -11.1 -- 8 18.6 -7.4 -- 10 25.4 -9.8 --

12.5 39.4 -14.1 -- 16 45.4 -12.0 -- 20 55.4 -13.0 -- 25 5.9 55.6 -21.5

31.5 -5.8 71.5 -26.6 40 65.4 -6.0 -6.0 50 -0.2 77.3 -32.1 63 -23.8 91.2 -34.3 80 -27.2 89.8 -33.3 100 87.4 -38.1 -- 125 91.4 -42.6 -- 160 93.2 -47.7 -- 200 99.1 -54.4 -- 250 80.0 -47.3 -- 315 41.3 -26.0 --



6.3 -0.3 0.2 -- 8 -1.9 0.5 -- 10 17.0 -11.5 --

12.5 25.4 -13.9 -- 16 58.2 -22.2 -- 20 60.1 -19.9 -- 25 50.7 -15.8 --

31.5 58.0 -19.9 -- 40 68.5 -23.6 -- 50 92.5 -35.2 -- 63 97.4 -38.5 -- 80 85.3 -33.1 --

100 85.9 -35.5 -- 125 85.7 -36.6 -- 160 89.6 -40.6 -- 200 87.9 -41.7 -- 250 68.9 -33.8 -- 315 41.8 -22.7 --


Frequency A B C 6.3 2.7 -0.1 -- 8 11.5 -4.6 -- 10 1.8 1.1 --

12.5 3.1 4.8 -- 16 14.1 -3.6 -- 20 22.9 -4.7 -- 25 42.6 -8.4 --

31.5 62.3 -15.3 -- 40 69.3 -18.9 -- 50 83.3 -27.7 -- 63 88.6 -32.2 -- 80 86.9 -33.4 -- 100 85.2 -35.4 -- 125 84.6 -38.1 -- 160 88.9 -43.2 -- 200 90.8 -46.2 -- 250 81.0 -43.3 -- 315 64.4 -36.6 --



6.3 4.3 -0.5 -- 8 4.1 -2.0 -- 10 11.8 -6.2 --

12.5 15.2 -6.3 -- 16 24.1 -6.8 -- 20 35.6 -7.7 -- 25 64.9 -19.3 --

31.5 81.4 -26.4 -- 40 86.6 -29.7 -- 50 97.9 -37.9 -- 63 105.4 -44.8 -- 80 100.9 -43.9 -- 100 95.6 -43.0 -- 125 88.2 -41.7 -- 160 75.7 -39.4 -- 200 87.0 -47.5 -- 250 79.4 -44.6 -- 315 88.5 -49.6 --


Frequency A B C 6.3 7.3 -3.0 8 14.5 -8.2 10 18.8 -10.5

12.5 25.8 -11.0 16 36.5 -13.0 20 48.5 -13.5 25 49.2 -9.9

31.5 67.1 -19.7 40 79.8 -26.5 50 93.5 -35.5 63 89.3 -34.6 80 95.0 -39.3 100 88.5 -39.0 125 72.5 -32.4 160 53.3 -23.4 200 50.7 -26.3 250 61.8 -36.1 315 45.4 -29.5


APPENDIX E AMBIENT NOISE MEASUREMENT SITES This section provides the detailed ambient noise data for the sites discussed in Section 4.0. A map of the test sites is provided in Figure 2. All data shown here was collected in December 2014.

FIGURE 64: N11 24-HR AMBIENT NOISE TIME HISTORY



It should be noted that some ambient data collected in 2011, which was equivalent to the N13 location, was used for examining the day/night pattern of sound levels in that area of the project; this allowed for estimation of a full 24-hour Ldn for N13. (Equipment malfunction resulted in the loss of 8 hours of data at N13.)


FIGURE 67: N14 1/2-HR AMBIENT NOISE TIME HISTORY



APPENDIX F SENSITIVE RECEIVER INVENTORY Table 34 lists the sensitive receivers potentially affected by the streetcar operations/construction and also the Traction Power Substations (TPSS). Figure 97 shows the area labels. Figure 98 through Figure 104 show the sensitive receivers along the proposed alignment, first for the whole alignment followed by areas of the alignment.

TABLE 34. SENSITIVE RECEIVER INVENTORY

Area ID* Location

Distance to

near track or or TPSS

(ft)

FTA category Type No. of

units

Streetcar

1 R1 Bridgeview Condominiums, E Rio Salado Pkwy 75 2 - residential MF 26

2 R2 Hayden Condos 154 W 5th St, SE corner of 3rd and Ash (NB side of st)

222 2 - residential MF 18

2 R3 Courtyard Hotel (NB side of st) 59 2 - residential HT 12 2 R4 111 6th St Condos (NB side of st) 196 2 - residential MF 96 2 R5 Encore on Farmer Senior Housing 198 2 - residential MF 24 4 R6 University Inn and Suites 51 2 - residential HT 3

4 R7 918 S Mill Ave - unclear if this is residence or business 66 2 - residential MF 1+

4 R8 1100 S Mill Ave 70 2 - residential SF 1 4 R9 1104 S Mill Ave 68 2 - residential SF 1 4 R10 1110 S Mill Ave 70 2 - residential SF 1 4 R10A 1112 S Mill Ave 71 2 - residential SF 1 4 R11 1160 S Mill Ave 83 2 - residential SF 1 4 R12 1170 S Mill Ave 95 2 - residential SF 1 4 R13 1190 S Mill Ave 107 2 - residential SF 1 4 R14 1202 S Mill Ave 155 2 - residential SF 1 4 R15 1204 S Mill Ave 182 2 - residential SF 1 4 R16 1208 S Mill Ave 219 2 - residential SF 1 4 R17 21 E 13th St 210 2 - residential SF 1 4 R18 25 E 13th St 173 2 - residential SF 1 4 R19 33 E 13th St 142 2 - residential SF 1 4 R20 Graduate Hotel 128 2 - residential HT 72 4 R21 ASU residence halls - Hayden 88 2 - residential MF 45

4 R22 ASU student housing - Villas at Vista Del Sol 50 2 - residential MF 44

4 R23 ASU student housing - Vista Del 70 2 - residential MF 44


Sol Towers I, J, and K

4 R24 ASU student housing - Adelphi Commons 61 2 - residential MF 12

4 R25 ASU residence halls - includes Chuparosa, Jojoba, Agave, Sage, Cereus, Cottonwood, Juniper


4 R26 apartments, 922 E Apache Blvd 43 2 - residential MF 44 4 R27 apartments, 977 E Apache Blvd 48 2 - residential MF 30 4 R28 Super 8 Hotel 66 2 - residential HT 8 4 R29 Holiday Inn Express Hotel 87 2 - residential HT 2 4 R30 apartments, 1123 E Apache Blvd 68 2 - residential MF 10 4 R33 Sunset Villas Apartments 55 2 - residential MF 12 3 R34 Tempe Mission Palms (Hotel) 175 2 - residential HT 20 4 R35 S Maple Avenue Homes 220 2 - residential SF 4 4 R36 Lennar Development 44 2 - residential MF

2 I1 Tempe Beach Park 54 W Rio Salado Pkwy 24 3 - institutional PK -

3 I2 Brickyard Engr. Bldg. 699 S Mill Ave 29 3 - institutional SC -

3 I3 Tempe Post Office 500 S Mill Ave 80 3 - institutional - -

4 I4

ASU building (use unknown, previously Ceramic Research Center) 10th and Mill

81 3 - institutional SC -

4 I5 Hillel Jewish Student Center 1012 S Mill Ave 57 3 - institutional CH -

4 I6 Alleluia Lutheran Student School 1034 S Mill Ave 69 3 - institutional SC -

4 I8 Birchett Park adjacent to Gammage Curve 30 3 - institutional PK -

4 I9 7th Day Adventist Church 41 E 13th St 110 3 - institutional CH -

4 I10 Ten40 Church 1040 E Apache Blvd 170 3 - institutional CH -

4 I11 Southwest Institute of Healing Arts (school) 1100 E Apache Blvd


4 I12 Southwest Institute of Natural Aesthetics (school) 1112 E Apache Blvd


4 I13 New School for the Arts and Academics 2016 E Apache Blvd


3 Special 1 Valley Art Theater 509 S Mill Ave 80 3 - institutional - -

4 Special 2 ASU New Music Building 50 E Gammage Pkwy 95 3 - institutional - -

4 Special 3 Gammage Auditorium 255 3 - institutional - -


1200 S Forest Ave

TPSS 2 I1 Tempe Beach Park 30 3 - institutional PK -

2 R2 Hayden Condos 154 W 5th St, SE corner of 3rd and Ash (NB side of st)


3 R34 Tempe Mission Palms (Hotel) 190 2 - residential HT 20 4 R35 S Maple Avenue Homes 50 2 - residential SF 4

4 (NA – TPSS only)

1303 S Mill Ave 40 2 - residential SF 1

4 I12 Southwest Institute of Natural Aesthetics (school) 1112 E Apache Blvd


1SF=single-family, MF=multi-family, HT=hotel, SC=school, PK=park, CH=church 2For the vibration analysis, receiver R31 used distance to special trackwork (100 ft) instead of distance to track to predict worst-case vibration level. * There is no I7 listed in this table; this identification was previously assigned to Chabad at ASU, which appears to now be located farther from the alignment. The sensitive receiver is now a residential land use, listed as receiver R10A. Also, R31 and R32 are not listed in this table; the Sonoran Ridge Apartments (R31) and Days Inn (R32) are replaced with the Lennar Development (R36).


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FIGURE 77: AREA 1 SENSITIVE RECEIVERS


FIGURE 80: AREA 4 (MILL AVE) SENSITIVE RECEIVERS


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appendix f noise and vibrationtechnical report - valley metro...appendix f . noise and...

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