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Element 1: 4-Step Project Selection Process

Element 1: 4-Step Project Selection Process. Element 1: The Systemic Safety Project Selection Process. Objective. Develop a prioritized list of locations that could benefit from systemic safety countermeasures

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Element 1: 4-Step Project Selection Process

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  1. Element 1: 4-Step Project Selection Process Element 1: The Systemic Safety Project Selection Process

  2. 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. Element 1, Step 2: Screen and Prioritize Candidate Locations

  3. Outcome • An assessment and rating of the focus facility type(s). • Identify locations considered for systemic safety improvements. Element 1, Step 2: Screen and Prioritize Candidate Locations

  4. 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 Element 1, Step 2: Screen and Prioritize Candidate Locations

  5. Element 1: Step 2 Element 1, Step 2: Screen and Prioritize Candidate Locations

  6. 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 1

  7. Element 1: Step 2, Task 1Identify Network Elements Analyzed Process: • 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 1

  8. Sample Segment & Curve

  9. 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 2

  10. 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 2

  11. Element 1: Step 2, Task 2Conduct Risk Assessment Process: • Record roadway and traffic characteristics for the selected risk factors • Document crash history (particularly severe focus crashes) for each location. Element 1: Step 2, Task 2

  12. Example Data Collected for Segments

  13. Video Logs 1 – Usable Shoulder, Reasonable Clear Zone • 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  3– No Usable Shoulder, Roadside with Fixed Obstacles 13

  14. Aerial Images for Segments • Segment Access Points • Curve – Visual Trap and Intersection     

  15. Aerial Images for Intersections • Skew • Intersection on/near horizontal curve • Railroad crossing • Commercial Development in quadrants

  16. 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 3

  17. Element 1: Step 2, Task 3 Prioritize Roadway Facilities Process: • 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 • Set a threshold (the number of risk factors present or a weighted value) used to identify high-priority candidates. • Flag the locations above the threshold. Element 1: Step 2, Task 3

  18. 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 Element 1: Step 2, Task 1

  19. Example County Curve Prioritization • Complete census of 504 curves • 32 High Priority Curves (6%) • 138 Curves in Proximity Element 1: Step 2, Task 1

  20. Example County Intersection Prioritization Is the County’s entire system equally at-risk? • No, about 41% of their system is a High Priority Element 1: Step 2, Task 1

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