roadway safety for local agencies doug bish traffic services engineer oregon department of...
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Roadway Safety for Local Agencies
Doug BishTraffic Services Engineer
Oregon Department of Transportation
Roadway Safety for Local Agencies
Diagnosing Crash Problems
The problem is this person has a moose in his car, most problems are not so easily diagnosed!
Roadway Safety for Local Agencies
Diagnosing Crash ProblemsSteps to Diagnosing Safety Problems• Quantify crashes by type and severity• Determine if there is a problem:
– abnormally high crashes in one or more areas; or – just high but normal patterns.
• Determine possible source of problem (major causes).
• Evaluate possible improvements for:– Potential crash reductions– Cost benefit of improvements.
Roadway Safety for Local Agencies
Diagnosing Crash ProblemsDiagnosis of a problem is not always self evident and
requires expert knowledge:• A “high” crash site does not always mean there is something abnormal or that there is
cost effective fix. • No baseline for determining if crashes are “high but normal patterns” or “there is
abnormal patterns”• Don’t always know best “treatment” for high crash location • Hard to identify the best candidate mitigations for improving safety
Roadway Safety for Local Agencies
Step 1 – Review Data (looking for patterns)
•Review and summarize data by:
•Crash type (Rear-end, Sideswipe, Angle, Turning, Head-on, etc)
•Crash severity (Fatal, Injury A, B, or C and PDO)
•Direction of travel
•Contributing circumstances (Lighting condition, road conditions, weather, impairment, etc)
Roadway Safety for Local Agencies
Crash Data
• Can be obtained with a call to ODOT’s Crash Analysis and Reporting Unit
(Robin shared with you some ways to obtain the data – it easier than you think)
Roadway Safety for Local Agencies
Scatter Plots
Roadway Safety for Local Agencies
Yearly Fatal and Injury Rates
Roadway Safety for Local Agencies
Crash Graphing Tool – day of the week, time of day, road condition (wet, dry), light condition (dark, light, dusk), alcohol impairment, crash type
Roadway Safety for Local Agencies
Crash Summary Database
Something like this will be available with the new SPIS
Roadway Safety for Local Agencies
Collision Diagram Tools
Roadway Safety for Local Agencies
Investigating in the Field
• Sometimes all the slicing and dicing of data doesn’t help
• An important part of any investigation is to gather information from different perspectives
Roadway Safety for Local Agencies
Investigating in the Field
• Visit the site, approach the area from all directions– If it is an intersection drive all legs of the
intersection• Take along a peer with different expertise• Talk to staff maintaining the roadway (or meet
them at the site)• Talk to public from around the area
(neighbors or business)• Talk to enforcement and EMS
Roadway Safety for Local Agencies
Choosing a Solution
• Once you have an idea of the problems you can begin to consider different fixes
• Try to avoid choosing solutions until you have gathered all the facts!
• Then compare different solutions by cost and benefit
Roadway Safety for Local Agencies
Crash Reduction Factors
Listed by Improvement Type
Rural Urban Fatal Non-Fatal PDO
ROADSIDE IMPROVEMENTS
Barrier & Guardrail:
Guardrail - install or improve X X 44-47 42-47 -
Guardrail at bridge end - install or improve X X 90 20-45 20-45
Median barrier - concrete, 3-6' shy distance X X 90 10 -10
Median barrier - concrete, 7-12' shy distance X X 85 5 -25
Median barrier - any X 60 -20 -40
Median barrier - metal X X 75 2 -28
Median barrier - cable X X 36 20 41
Install animal fencing X X 70-90 70-90 61
impact attemuators X X 75-90 50 5-50
Clear Zone:
Clear gore area X 50 50 25
Flatten side slopes from 1:2 to 1:4 X 7 7 7
Flatten side slopes from 1:2 to 1:6 X 15 15 15
http://www.oregon.gov/ODOT/HWY/TRAFFIC-ROADWAY/docs/excel/CRFWorksheet.xls
Roadway Safety for Local Agencies
Benefit/Cost Worksheethttp://www.oregon.gov/ODOT/HWY/TRAFFIC-ROADWAY/docs/excel/BC_Form.xls
Roadway Safety for Local Agencies
Low Cost Countermeasures
• Handouts – Low Cost Safety Solutions excel spreadsheet
Roadway Safety for Local Agencies
National Publications• Low Costhttp://docs.mvrpc.org/safety/
Low_Cost_Local_Roadway_Safety_Solutions.pdf
• Lane departurehttp://www.t2.unh.edu/nltapa/Pubs/PLD-1.pdf
• NCHRP Safety Emphasis Guides
http://safety.transportation.org/guides.aspx
• Highway Safety Manual(Available Spring of 2010)
Roadway Safety for Local Agencies
Questions?
Doug Bish
Traffic Services Engineer
Oregon Department of Transportation
http://www.oregon.gov/ODOT/HWY/TRAFFIC-ROADWAY/highway_safety.shtml