1. Clark County, WA Safety Management Program
Western District ITE
Monterey, CA
June 23rd, 2019

2. Agenda Background Goals Safety Management Program
Systemic Safety Improvement Program
8/9/17

3. Background
Historically County had used traditional method of managing traffic safety
Vision of a reliable and defensible technique to screen and prioritize projects
Traditional methodology dealt with absolutes in terms of safety improvements
Highway Safety Manual can provide quantitative value for nominal safety improvements resulting in estimates for benefit cost ratio
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4. OVERALL: Best use of County Funding
Goals
The Clark County Safety Program was established with the following goals:
Better identify locations for potential safety improvement projects
Use an objective data-driven process to prioritize locations throughout the County
Develop projects for high priority locations
Quantify and compare the benefit-cost ratio of any potential improvements
OVERALL: Best use of County Funding
8/9/17

5. Safety Management Systemic Safety
Safety Program
Data driven
Screening based on reported crashes
Range of improvement options at one specific site
Safety Management
Risk factors identified with reported crashes and roadway characteristics
Focused on low cost improvements at various sites
Systemic Safety
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6. Data – Due Diligence Data located in County’s GIS database: Crash data
Date
Severity
Crash type
Roadway inventory data
County road log number and mileposts
Functional classification
Traffic volume data (ADT)
Posted speed (miles per hour)
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7. Safety Management Program Framework
1) Network Screening
Split into reference populations
Run analysis to calculate performance measures used for ranking
Identify top 5% safety need locations
2) Project Development
Identify top 15 intersections and segments
Crash diagrams and site visit
Identify Contributing Factors
Identify Potential Countermeasures
3) Project Ranking
Calculate project costs
Estimate benefits over design life
Rank by benefit-cost ratio
Based on the AASHTO Highway Safety Manual’s (HSM) Roadway Safety Management Process.
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8. Network Screening Process
A) Establish Reference Populations
Identify distinct roadway characteristics
Group sites (segments or intersections) with similar roadway characteristics into subsets of County
Establish number of populations for network screening
B) Establish Priority Areas
Conduct crash analysis to identify over-represented crash types
List of safety priority areas
C) Select Performance Measures
Measures reflect Priority Areas
Establishes methodology for ranking sites
D) Screen Network
Apply performance measures
Identify sites that exceed performance measure(s)
Rank sites within reference populations
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9. Network Screening – Reference Populations
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10. Network Screening – Reference Populations
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11. Network Screening – Performance Measures
Crash-Critical Crash Rate Ratio
Frequency of Fatal and Severe Injuries
Excess Proportion of Specific Crash Type
Annual Equivalent Property Damage Only Score
Performance measures were selected to account for crash severity, frequency, and types.
8/9/17

12. Network Screening – Excess Proportion Crash Types
Intersection
Segment
Angle*
Angle
Opposite Direction
Opposite Direction*
Fixed Object
Fixed Object*
Bicycle or Pedestrian
Alcohol Impaired
*Primary Crash Type
8/9/17

13. Network Screening – Performance Measures
Description
Maximum
Scoring
Crash-Critical Crash Rate Ratio
Compares crash frequency normalized by ADT to similar facilities
1.0
Frequency of Fatal or Severe Injuries
Accounts for presence of a fatal or Injury A crash (and quantity)
1.5
Excess Proportion of Specific Crash Type
Identifies locations where the proportion of a specific crash type exceeds the average for similar sites
Annual Equivalent Property Damage Only Score
Assigns weight based on frequency of crashes by severity level
Maximum total score of 5.0
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14. Project Development and Ranking Process
Select Sites from Network Screening Results
Diagnose and Select Countermeasures
Evaluate Project Benefit/Cost and Rank Projects
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15. Priority Locations Top 5% of locations from network screening
180 intersections
400 segments
Evaluate top sites based on recent context:
Remove locations where improvements are already identified
Remove locations that may be impacted by other construction
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16. Site Reviews Field visits at priority intersections and corridors
Includes the following items:
Review crash trends to identify potential problems at the site (collision reports)
Observe traffic operations
Measure sight distances, as needed
Drive approaches or corridors to evaluate from users perspective
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17. Crash Prediction Long-Term Expected Average Number of Crashes
minimizes influence of the randomness of crashes
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18. Project Packages and Benefit/Cost
Two tiers: near-term and long-term project packages
Tier I—Lower cost, higher ease of implementation
New signs and striping
Signal timing and phasing changes
Shoulder rumble strips
Tier II—Higher cost, lower ease of implementation
Intersection lighting
Adding turn lanes
Widening shoulders
Guardrails
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19. Project Packages and Benefit/Cost
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20. Intersection Prospectus Sheet
8/9/17

21. Segment Prospectus Sheet
8/9/17

22. Systemic Safety Improvement Program
Provides low cost safety countermeasures that can be applied at various locations with the same risk factors
Toolbox of treatments for County’s most prevalent risk factors:
Rural road curves and grades on high-speed roadways
Rural road fixed objects, including trees, stumps, posts, poles, embankments, or ledges
Rural two-way stop controlled intersections
Urban signalized intersections
Pedestrian crossings on multi-lane urban roadways
8/9/17

23. Top Locations for Consideration
Rural Curves
Rural Two-Way Stop-Controlled Intersection Corridors
NE Lucia Falls Rd between NE 172nd Ave and NE Sunset Falls Rd
NW 199th St between 41st Ave and NE 29th St
NE 119th St between NE 119th St and NE 172nd Ave
Intersections created by NE 82nd St, NE 259th St, NE 72nd St, and NE Manley Rd
NE Risto Rd between NE 207th Ave and NE 227th Ave
NE 182nd St between NE Risto Rd and NE 119th St
Rural Slopes
SE Blair Rd between SE Washougal River Rd and WA-500
NE WH Garner Rd to NE Kelly Rd, continuing to NE Yacolt Mountain Rd
Signalized Intersections
NE Sunset Fall Rd between NE Deer Rd and NE Lucia Falls Rd
NE 99th St and NE HWY 99
NE 78th St and NE HWY 99
Rawson Rd between NE 271st Ave and NE 139th St
NE St Johns Rd and NE 78th St
Rural Fixed Objects
NE Covington Rd and NE 76th St
NE Lucia Falls between NE 172nd Ave and NE Sunset Falls Rd
Pedestrian Corridor
Washougal River Rd between County Line and SE 17th St
NE 99th St between NE Hazel Dell Ave and NE 25th St
Connection between NE 27th Ave at NE Blair Rd and NE 39th St at NE 292nd Ave
NE 78th St between NE Hazel Dell Ave and NE St Johns Rd
NE HWY 99 between Minnehaha St and NE 104th St
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24. 8/9/17

25. 8/9/17

26. Questions
Ejaz Khan, P.E. Clark County, Washington
Courtney Furman, P.E. Clark County, Washington
8/9/17