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The State Route 246Central Avenue Ext. and Purisima Road

Traffic Study

May 2008

Objective of the StudyTo examine the 2030 traffic impacts associated with four roadway improvement alternatives to access the City of Lompoc from Route 246 and to evaluate the critical intersection LOS within in the study area.

Interagency Steering Committee: City of Lompoc, County of Santa Barbara, Caltrans, SBCAG

The Four AlternativesAlt 1 – 2030 No-Build (Programmed Forecast)

Alt 2 – 2030 Central Ave Ext. as a 2-Lane Minor Arterial

Alt 3 – 2030 Central Ave Ext. as a 4-Lane Minor Arterial

Alt 4 – Widen Rt. 246 e/o Rt. 1 to a 4-Lane Minor Arterial

Socioeconomic Forecast for the Study Area

Lompoc & Unincorp Areas 2000 2030 % Incr.Population 46,347 62,846 35.6%Households 14,876 18,918 27.2%Employment 12,030 16,518 37.3%

(03) 8900, PH = 9.2%

(03) 11540, PH = 8.5% (06) 11100. PH = 9.0%

(03) 9200, PH = 12.6% (06) 8600, PH = 9.9 %

(03) 33740, PH = 6.8% (06) 31480, PH = 8.2%

(03) 16240, PH = 8.6% (04) 13800, PH = 8.3%

Daily & PMPH Traffic

8900, Trucks = 4%

11540, Trucks = 4%

9200, Truck = 11%

33740, Trucks = 5.6%

16240, Truck = 6.3%

Traffic and Truck %

Distribution by Truck Type - PM Peak HourCentral Ave e/o H Street - Eastbound

0

5

10

15

20

25

2-4 Axle Unit Truck Semis Tractor-Trailers

Num

ber o

f Tru

cks

File : H:\NewMo del\246Study/Centra l Ave Tk Tx 2002

2002 Traffic Distribution - PM Peak Hour Central Ave e/o H Street - Eastbound

2.0%

68.0

%

23.5

%

0.3% 6.

2%

0%

20%

40%

60%

80%

100%

Motorcyles&Bikes

Auto P.Up Buses Trucks

Truck Traffic

Four Study Alternatives

Traffic Impacts: Alt. 1 vs. Alt. 2

Traffic Impacts on City's Arterials Alt. 1 vs. Alt. 2

-

5,000

10,000

15,000

20,000

25,000

30,000

Alt 1 (No Project) Alt 2 (Central Ext. 2-Ln)

Central e/o O St North w/o H St H St n/o College

Impacts on Central Ave Ext'nAlt. 1 vs. Alt 2

-

5,000

10,000

15,000

20,000

25,000

Alt 1 (No-Build) Alt 2 (Central Ext. 2-Ln)

Central Ext'n w/o Rucker Ocean e/o 7St SR246 e/o Rt1

Traffic Impacts on Central Ext., Rt. 1 & Ocean Alt. 1 vs. Alt. 2

-

10,000

20,000

30,000

40,000

50,000

Alt 1 (No-Build) Alt 2 (Central Ext. 2-Ln)

Central e/o H St Rt. 1 n/o Central Ocean e/o H St

Critical Intersection LOS Analysis

• Focus on P.M. Peak Hour• Forecast

– Growth factors from SBCAG model– Applied to current turning movement count data

• Level of Service (LOS)– Grades A (free-flow conditions) through F (heavy

congestion)– Intersection Capacity Utilization (ICU) Methodology

• Some capacity improvements were assumed to be in place for the Year 2030 scenario

Critical Intersection LOS Analysis

Intersection Improvements Assumed for Analysis

1. Purisima Rd/H St-Rte. 1 One SB through lane added south of intersection *

2. Purisima Rd/Rte 246 Traffic signal*

3. Central Ave/H St Add one left-turn lane on NB and SB approaches*

* Source: Wye Specific Plan EIR

1

23

YEAR 2030 P.M. PEAK HOUR INTERSECTION LOSALTERNATIVE 1

YEAR 2030 P.M. PEAK HOUR INTERSECTION LOSALTERNATIVES 2 & 3

Intersection Improvements Assumed for Analysis

1. Purisima Rd/H St-Rte. 1 One SB through lane added south of intersection *

2. Purisima Rd/Rte 246 Traffic signal*

3. Central Ave/H St Add one left-turn lane on NB and SB approaches*

4. A St/Central Ave Traffic signalWiden NB and EB approaches

5. Central Ave/Rte 246 Traffic signal

* Source: Wye Specific Plan EIR

1

32

45

Intersection Improvements Assumed for Analysis

1. Purisima Rd/H St-Rte. 1 One SB through lane added south of intersection *

2. Purisima Rd/Rte 246 Traffic signal*

3. Central Ave/H St Add one left-turn lane on NB and SB approaches*

* Source: Wye Specific Plan EIR

YEAR 2030 P.M. PEAK HOUR INTERSECTION LOSALTERNATIVE 4

1

2

3

Conclusions• Alt. 2 provides a direct access from Rt.246 to the City of

Lompoc. The Central Ave Ext. has a significant impact in terms of:– Diverting approx. 8,100 ADT (46%) traffic volumes from Rt.246– Providing a primary truck access from Rt. 246 to the City and nearby

communities– Facilitating an alternate route for traffic between Downtown and Mesa

Oaks/Mission Hills– Increasing PM peak volumes on Central Avenue by approx. 15-30%

• Alt. 3 offers no significant benefits with the added capacity on the Central Ave Extension.

• Alt. 4 does not appear to provide any operational benefits.• With adequate capacity improvements in place, most study area

intersections would operate efficiently with Central Avenue Extension except the Central Avenue and H Street intersection.

• Interagency MOU between County, City of Lompoc, and SBCAG for continued study of improvement alternatives. Cost sharing among County and City with SBCAG as Project Manager

• RFP for Feasibility Study to examine costs (e.g. bridge, road improvements), environmental issues (e.g. sensitive habitats), etc. of improvement alternatives

• Feasibility Study subject to public review

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