1 / 55

Road Safety Management Process

Road Safety Management Process. Roadway Safety Management Process. Prioritization of Improvement Projects. Network Screening. Countermeasure Selection. Network Screening. 6. 7. 9. 5. 8. 4. Diagnosis. Economic Appraisal. Safety Effectiveness Evaluation. Methods for Identifying Sites.

neve-wagner
Download Presentation

Road Safety Management Process

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Road Safety Management Process

  2. Roadway Safety Management Process Prioritization of Improvement Projects Network Screening Countermeasure Selection Network Screening 6 7 9 5 8 4 Diagnosis Economic Appraisal Safety Effectiveness Evaluation

  3. Methods for Identifying Sites The identification, examination and effective treatment of well-chosen sites will yield safety improvements…

  4. Methods for Identifying Sites • Goal – Identify and rank “sites with promise” • Those sites that, if treated, will experience decreases in crashes • Example methods • Public involvement? Political pressure? • High crash frequency history • High crash rate • Severity-weighted frequency (based on crash costs) • Excess crashes • Etc.

  5. Example: Excess Crashes • Compare actual crashes to expected crashes for this category of sites (e.g., two-lane rural intersections) • More details in Unit 4

  6. Network Screening • Identify sites that may benefit the most from a treatment • Establish Focus • Specific crash types (e.g., wet weather crashes) • Specific facility types (e.g., intersections) • Specific area/corridor • Select reference population • Groups of sites with similar characteristics • Select performance measures • Select screening method and do the screening

  7. Performance Measures • 13 performance measures listed in the Highway Safety Manual • Range from very simple measures based on average crash frequency to advanced measures based on the empirical Bayes method

  8. How to Select a Performance Measure? • Data Availability • Is traffic volume data available? • Are Safety Performance Functions available? If no, can they be estimated? • Does the performance measure account for Regression-to-the-Mean Bias

  9. How to Identify Sites with Promise? • Expected Number of Crashes • Excess Expected Difference compared to the average for comparable sites (also called deviation from the norm) • Can be used Identify deviant sites • Can use empirical Bayes method to estimate expected crashes

  10. Determining deviant sites Expected crashes (based on EB method) Excess A Crashes per Unit Time SPF representing average for comparable sites (norm) Traffic Volume

  11. Diagnosis • Crash Factors • Human • Roadway • Vehicle • Environmental • Collision Type • Run-off Road • Rear End • Head On • Sideswipe Same Direction

  12. Site Review Methods • Engineering Road Safety Audits • Immediate improvements (maintenance) • Low cost safety improvements • High cost safety improvements • Crash history • Collision diagram

  13. Example Collision Diagram

  14. Motives for Action • Economic Efficiency • Professional and Institutional Responsibility • Fairness

  15. Countermeasure Selection

  16. Tools For Identifying Countermeasures • Engineering studies • Road safety audits • The Australian Safe Systems Approach • The Haddon matrix

  17. Engineering Studies • Step 1: Examine the Crash Data • Step 2: Conduct a Field Study • Step 3: Identify Potential Countermeasures • Step 4: Prioritize Countermeasures • Step 5: Implement the Chosen Countermeasure(s) • Step 6: Evaluate the countermeasure impact

  18. Road Safety Audits • Used for Roadway Corridors, Both Existing and New (Canada) • Characteristics of RSAs • A formal examination with a structured process; • Conducted independently by professionals who are not currently involved with the project; • Completed by a team of qualified professionals representing appropriate disciplines; • Focuses solely on safety issues; and • Examines the transportation site with respect to all potential road users.

  19. The Australian “Safe Systems Approach” • How? • Safer vehicles • Safety roads and roadsides • Controlling speeds • Can’t Prevent All Crashes • But Try To Assure No Serious Injuries or Deaths

  20. The Haddon Matrix • Crash-Related Factor Categories • Human • Vehicle • Roadway • Environmental • Crash Time • Pre Crash • Crash • Post Crash

  21. The Haddon Matrix (cont.) • Can be use to • Categorize existing treatments to identify cells with few • Categorize factors (e.g., fatigue, ambulance delay) to generate new treatments.

  22. The Haddon Matrix -- Exercise • Graduated Drivers Licensing • Airbags • Driver risk-taking propensity • Seat Belt Use • Distance to hospital • Electronic stability control • Driver age • Emergency Med. Svs. Training • GPS automatic crash notification • Rumble strips • Median barrier • Distance to roadside object

  23. The Haddon Matrix (cont.)

  24. Sources for Potential Countermeasures • Roadway Countermeasures • NCHRP Series 500 • Highway Safety Manual, Part D • FHWA Crash Modification Factor Clearinghouse • FHWA list of suggested (proven) countermeasures • NCHRP Report 617, Accident Modification Factors for Traffic Engineering and ITS Improvements • Behavioral Countermeasures • Countermeasures That Work

  25. Countermeasure Sources:NCHRP Series 500 Guides • Countermeasures classified as: • Proven, • Tried, or • Experimental • Examples: • Relocate roadside objects (P) • Install shoulder rumble strips (T) • Delineate poles with retroreflective tape (E)

  26. Countermeasure Sources:Highway Safety Manual • First edition released in 2010 • Provides practitioners with the best factual information and tools regarding safety consequencesof design decisions. • Sections • Part A: Safety knowledge • Part B: Safety management • Part C: Crash prediction models • Part D: Countermeasure selection and CMFs

  27. Countermeasure Sources:Crash Modification Factors Clearinghouse

  28. Countermeasure Sources:FHWA Suggested Countermeasures (2008) • Road safety audits • Rumble strips and rumble stripes • Median barriers • Safety edge • Roundabouts • Left and right turn lanes at stop-controlled intersections • Yellow and all red change intervals at traffic signals • Median and pedestrian refuge areas in urban and suburban areas • Walkways

  29. Countermeasure Sources:NHTSA “Countermeasures That Work”

  30. Question • When faced with many potential countermeasures, how does one choose which one(s) to implement?

  31. Comparing Countermeasures • Subjective comparisons • Which will garner the most public support? • Which is most appropriate for the area? • Objective comparisons • Expected effectiveness -> decreases in crashes (CMFs) • Expected costs -> installation and maintenance

  32. Market Research for Targeting Countermeasures • Identifying sub-population characteristics • Easing language barriers • Customizing campaigns and programs

  33. Market Research Techniques • What types of market research techniques can be used to target high crash risk groups?

  34. Market Research Techniques • Focus groups • Surveys • Observational studies

  35. Cost Effectiveness of Alternative Countermeasures Prioritize interventions and countermeasures based on effectiveness.

  36. Major Topics • Countermeasure Costs and Benefits • Programming Projects • Qualitative Considerations • Countermeasure Evaluation

  37. Countermeasure Costs • Startup or installation costs • Example? • Ongoing operational or maintenance costs • Example? • Resilience/staying power (“usable life”) • Which countermeasures would have shorter staying power? Which would be longer?

  38. Countermeasures Benefits • Crashes prevented – use CMFs to estimate if available • Changes in crash severity • Signals and red light cameras • Cable median barriers • Other benefits not related to safety (e.g., reduced delay)

  39. Countermeasure Benefits:Crash Modification Factors • Crash modification factor (CMF) is a multiplicative factor used to compute the expected number of crashes after implementing a given countermeasure at a specific site. • CMF = • CMF > 1 indicates an expected increase in crashes • CMF < 1 indicates an expected decrease in crashes Expected crashes with countermeasure Expected crashes without countermeasure

  40. Countermeasure Benefits: Issues in developing CMFs • Isolating specific treatments or populations • Data availability • Detailed data not collected (e.g., installation date, etc) • Countermeasure not installed anywhere yet • Time • Money

  41. Countermeasure Benefits: Tools and Resources for CMFs • Highway Safety Manual • CMF Clearinghouse • SafetyAnalyst • The Interactive Highway Safety Design Model (IHSDM) • NCHRP Report 622, Effectiveness of Behavioral Highway Safety Countermeasures

  42. Countermeasure Benefits: Assigning Monetary Value to Crashes Prevented • Complex Process • Rules of Thumb • Fatal plus Serious Injury vs. minor injury plus PDO Costs • Cost Effectiveness

  43. Countermeasure Benefits: Example Crash Costs Source:  Highway Safety Manual, First Edition, Draft 3.1, April 2009.

  44. Benefit and Cost Analysis • Striving for the most effective use of limited safety funds (“bang for the buck”) • Rank competing projects • Methods • Benefit-cost ratio • Present value of benefits

  45. Example Benefit-Cost Ratios Countermeasure benefits Benefit-cost ratio = Countermeasure costs http://www.dot.state.mn.us/trafficeng/otepubl/fundamentals/safetyfundamentals.pdf

  46. Project Programming Techniques • Ranking • Weighting • Linear Programming

  47. Other (Qualitative) Considerations • What are other considerations that can play a role in which countermeasures are implemented?

  48. Other (Qualitative) Considerations • Design Standards • Tradeoffs • Familiarity • Constituent Concerns • How do we integrate these into science-based safety decisions?

  49. Post-Implementation Evaluation • Evaluation is essential to establish countermeasure effectiveness • Funds should be set aside for scientific evaluation

  50. Example Collision Diagram – After Countermeasure Was Installed Crashes decreased. Was all of the decrease due to the conversion to all way stop?

More Related