Download - Element 1: 4-Step Project Selection Process
1Element 1: The Systemic Safety Project Selection Process
Element 1: 4-Step Project Selection Process
Objective
• Develop a prioritized list of locations that could benefit from systemic safety countermeasures– Prioritized = Risk assessment for future crash;
answers to question if all elements are equally at risk.
– Location = Specific sites from focus facility type; including segments, curves, intersections, etc.
2Element 1, Step 2: Screen and Prioritize Candidate Locations
Outcome
• An assessment and rating of the focus facility type(s).
• Identify locations considered for systemic safety improvements.
3Element 1, Step 2: Screen and Prioritize Candidate Locations
Data Needs• Location of focus facility type
– Signalized intersections– Horizontal curves– Divided corridors– Etc.
• Site specific crash information – Severity, – Crash type– Relevant contributing factors
• Traffic and geometric information– At minimum, for risk factors– Additional information may be needed for selecting countermeasure
4Element 1, Step 2: Screen and Prioritize Candidate Locations
Element 1: Step 2
5Element 1, Step 2: Screen and Prioritize Candidate Locations
Element 1: Step 2, Task 1Identify Network Elements Analyzed
Purpose:• Identify the all locations from the focus facilities
– A census, not a sample
Resources:• Road and intersection data• Crash data at statewide and regional levels
Element 1: Step 2, Task 16
Element 1: Step 2, Task 1Identify Network Elements Analyzed
Process:1. Identify ALL locations from focus facility type.
– Curves & Intersections: identify eligible locations – Segments:
Split corridors into elements with consistent traffic and design characteristics (i.e., cross section)
Identify logical segment endpoints
2. Are risk factors feasible for a systemwide analysis?– Did you notice anything that suggests a need to change
risk factors?
Element 1: Step 2, Task 17
Sample Segment & Curve
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Element 1: Step 2, Task 2Conduct Risk Assessment
Purpose:• Document the conditions (i.e., risk factors)
at each location selected for analysis.
Suggestion
• While collecting information about risk factors, consider what data might be needed to assign/select the countermeasure.
Element 1: Step 2, Task 29
Element 1: Step 2, Task 2Conduct Risk Assessment
Resources:• GIS• Electronic inventories of roadway features and traffic
characteristics• Data collected as part of a field review• Archives of as-built plans• Aerial photography/street views• Video logs• Traffic control device inventories• Traffic flow maps
Element 1: Step 2, Task 210
Element 1: Step 2, Task 2Conduct Risk Assessment
Process:1. Record roadway and traffic characteristics for the
selected risk factors2. Document crash history (particularly severe focus
crashes) for each location.
Element 1: Step 2, Task 211
Example Data Collected for Segments
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Video Logs
• Edge Risk Assessment– See photos
• Lane Width• Shoulder Width/Type• Posted Speed Limit• Curve Signing• Sample Percent No
Passing
2 – Usable Shoulder, Roadside with Fixed Objects
1 – Usable Shoulder, Reasonable Clear Zone
3 – No Usable Shoulder, Roadside with Fixed Obstacles 13
Aerial Images for Segments
• Segment Access Points• Curve – Visual Trap and Intersection
146/2011
Aerial Images for Intersections
• Skew• Intersection on/near
horizontal curve• Railroad crossing• Commercial
Development in quadrants
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Element 1: Step 2, Task 3Prioritize Roadway Facilities
Purpose:• Use risk factors to assess locations’ risk.
• Identify top sites considered for countermeasure implementation.
Element 1: Step 2, Task 316
Element 1: Step 2, Task 3 Prioritize Roadway Facilities
Process:1. Prioritize roadway facilities using one of two methods to weight risk
factors:– Equal weight to risk factors
Identify the risk factors present for each location Sum the total number of risk factors for each location Prioritize locations based on number of risk factors present
– Weighted risk factors Assign relative weights to each risk factor Calculate a score for each location Prioritize locations based on total score
2. Set a threshold (the number of risk factors present or a weighted value) used to identify high-priority candidates.
3. Flag the locations above the threshold.
Element 1: Step 2, Task 317
Example County Segment Prioritization
Is the County’s entire system at-risk?– No, about 25% of their miles were
determined to be a High Priority
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Totals
# % Mileage %««««« 2 3% 7.4 2%«««« 4 5% 17.9 4%««« 16 21% 75.3 19%«« 28 36% 150.6 38%« 20 26% 108.0 27%
- 7 9% 41.4 10%
77 100% 400.6 100%
Rank Corridor Route # Start End Length ADTADT
RangeRD
DensityAccess Density
Curve CriticalRadius Density
Edge Risk
Totals
Tiebreakers
Edge RiskRD
Density
1 144.01 CNTY 89 CSAH-30 CSAH-30 1.4 480 « « « « « ««««« 3 0.28
2 40.04 CSAH 40NEW LONDON CORP LIM CSAH-2 5.9 450 « « « « « ««««« 2 0.17
3 131.01 CNTY 89 CSAH-30 MNTH-23 0.7 145 « « « « «««« 2 0.29
4 9.02 CSAH 9CR-90 , WILLMAR CORP LIM CSAH-10 5.6 940 « « « « «««« 1 0.14
5 5.06 CSAH 5150TH AVE NW CSAH-29 CSAH-1 10.1 628 « « « « «««« 1 0.14
6 31.02 CSAH 31NEW LONDON CORP LIM MNTH-23 1.6 920 « « « « «««« 1 0.13
7 8.01 CSAH 8RENVILLE COUNTY LINE
LAKE LILLIAN CORP LIM 3.6 750 « « « ««« 2 0.33
8 4.01 CSAH 4 CSAH-8 CSAH-20 6.7 320 « « « ««« 2 0.099 2.05 CSAH 2 CSAH-10 MNTH-23 9.8 385 « « « ««« 2 0.0410 4.04 CSAH 4 CR-98 CSAH-40 2.4 290 « « « ««« 2 0.0011 38.01 CSAH 38 CSAH-40 CSAH-48 2.1 130 « « « ««« 2 0.0012 132.01 CNTY 89 CSAH-8 CSAH-8 2.2 190 « « « ««« 2 0.0013 42.01 CSAH 42 CSAH-7 COUNTY LINE 0.5 120 « « « ««« 2 0.00
14 9.03 CSAH 9 CSAH-10 CSAH-40 , REDWOOD ST 4.9 1,800 « « « ««« 1 0.45
15 25.01 CSAH 25 CSAH-5 USTH-71 3.2 1,315 « « « ««« 1 0.25… … … … … … … … … … … … … … … …… … … … … … … … … … … … … … … …74 1.03 CSAH 1 MNTH-23 PENNOCK CORP LIM 7.0 333 1 0.0375 116.02 CNTY 89 CSAH-3 MNTH-40 7.0 98 1 0.0376 2.04 CSAH 2 ATWATER CORP LIM CSAH-10 6.7 1,018 1 0.0077 28.02 CSAH 28 CSAH-2 COUNTY LINE 2.0 315 1 0.00
Total Stars -- 26 33 34 33 22% That Gets Star -- 36% 46% 47% 46% 31%
Element 1: Step 2, Task 1
Example County Curve Prioritization
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Complete census of 504 curves32 High Priority Curves (6%)138 Curves in Proximity
Chevrons in PlaceStars # % # %
««««« 0 0% 0 0%«««« 7 1% 2 0%««« 25 5% 4 1%«« 108 21% 1 0%« 250 50% 2 0%- 114 23% 5 1%
504 100% 14 3%
Crashes Severe RoR
CurveCount
ID Corridor Segment Total Severe K A B C PDO K ARadius
(ft)Length
Curve (ft)ADT
Intersectionon Curve
ChevronsVisualTrap
Rank ProximityChevron
Candidate
1 001A 1.01 CSAH 1 1 - - - - - 1 - - 92 125 50 - - - 2 001B 1.01 CSAH 1 - - - - - - - - - 557 422 50 - - - « 3 001C 1.01 CSAH 1 - - - - - - - - - 823 493 50 - - - « 4 001D 1.01 CSAH 1 - - - - - - - - - 379 359 50 - - - 5 001E 1.01 CSAH 1 - - - - - - - - - 669 456 50 - - - « 6 001F 1.01 CSAH 1 - - - - - - - - - 270 431 50 - - - 7 001G 1.01 CSAH 1 - - - - - - - - - 314 324 50 - - - 8 001H 1.01 CSAH 1 - - - - - - - - - 545 239 50 - - - « 9 001I 1.01 CSAH 1 - - - - - - - - - 459 225 50 - - - 10 001J 1.01 CSAH 1 - - - - - - - - - 368 274 50 - - - 11 001K 1.01 CSAH 1 1 - - - - - 1 - - 318 390 50 - - - 12 001L 1.01 CSAH 1 - - - - - - - - - 267 399 50 - Yes - Installed13 001M 1.01 CSAH 1 - - - - - - - - - 1,475 345 50 - - - « 14 001N 1.01 CSAH 1 - - - - - - - - - 763 578 130 Yes - - «« 15 001O 1.01 CSAH 1 - - - - - - - - - 859 353 210 Yes - - «« 16 002A 2.02 CSAH 2 1 - - - 1 - - - - 583 752 930 - - - «« Yes Yes17 002B 2.02 CSAH 2 - - - - - - - - - 584 635 930 Yes - - ««« - Yes18 002C 2.02 CSAH 2 - - - - - - - - - 799 665 930 Yes - - ««« - Yes19 002D 2.02 CSAH 2 - - - - - - - - - 963 626 930 - - - «« Yes Yes20 002E 2.02 CSAH 2 - - - - - - - - - 1,234 584 930 - - - «« Yes Yes21 002F 2.02 CSAH 2 - - - - - - - - - 1,188 719 930 - - - «« Yes Yes22 002G 2.02 CSAH 2 1 1 - 1 - - - - 1 938 556 930 - - - ««« - Yes23 002H 2.02 CSAH 2 - - - - - - - - - 1,199 402 930 - - - «« Yes Yes… … … … … … … … … … … … … … … … … … … … … …… … … … … … … … … … … … … … … … … … … … … …… … … … … … … … … … … … … … … … … … … … … …
502 249ZH 249.01 CR 249 - - - - - - - - - 432 301 275 Yes - - Yes Yes503 249ZI 249.01 CR 249 - - - - - - - - - 814 344 275 - - - Yes Yes504 249ZJ 249.01 CR 249 - - - - - - - - - 800 685 275 - - - « Yes Yes
Element 1: Step 2, Task 1
Example County Intersection Prioritization
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Is the County’s entire system equally at-risk?
–No, about 41% of their system is a High Priority
# %««««««« 0 0%«««««« 0 0%««««« 0 0%«««« 8 11%««« 21 30%«« 33 46%« 9 13%- 0 0%
71 100%Element 1: Step 2, Task 1