180 likes | 188 Views
PIARC T.C. C2.1 & C2.3 Comparison of National Road Safety Policies & Plans Crash Analysis/Problem Definition & Time of Return Methodology October 2008. Larry E. Tibbits Michigan Department of Transportation Kuala Lumpur, Malaysia. Crash Information in Michigan to Define Problems Areas.
E N D
PIARC T.C. C2.1 & C2.3 Comparison of National Road Safety Policies & PlansCrash Analysis/Problem Definition&Time of Return MethodologyOctober 2008 Larry E. Tibbits Michigan Department of Transportation Kuala Lumpur, Malaysia
Crash Incident Documentation/ Processing • Crash report is completed by Law Enforcement Officer • All crashes involving injuries, and most property damage crashes must be reported • Statewide standard crash report form (next slides) • Paper and electronic version of crash report form • All reports processed by Michigan State Police • All reported crashes are located on linear and GIS based referencing systems
Crash Processing • Scan the form and create electronic image • Use intelligent character recognition of written information • Validate text data • Attach location information • Post crash data to crash data warehouse
Safety Analysis to DefineProblem Areas • Michigan Strategic Highway Safety Plan – data driven identification of 12 safety focus areas • Identification of Engineering, Enforcement, Education, and Emergency Medical Services treatments • Highway Safety Improvement Program (HSIP) • Identify high crash locations for treatment • 5% Report – worst 5% of locations statewide • Post safety treatment evaluations • Call for Safety Projects
Safety Analysis to DefineProblem Areas Of the 12 SHSP focus areas, three are predominately addressed by the HSIP: • Intersection safety • Pedestrian and Bicycle Safety • Lane Departure
Safety Analysis to DefineProblem Areas These locations are identified through: • High crash list • 5% Report • Fatality and serious Region wide maps • Project Required Safety Reviews • Customer concerns • Pavement friction analyses
Time of Return (TOR) • It is one type of cost benefit tool • Estimates benefits (reducing crashes/injuries/deaths) • Output: the number of years required to recover the safety investment • Based upon Roy Jorgensen’s report on Highway Safety Improvement Criteria
Why Use TOR • Federal Highway Safety Improvement Program requires that we invest safety dollars where they are needed most – where we get the greatest return • Helps prioritize competing safety projects • Verifies how the safety fix matches the demonstrated safety problem
Crash Data used in TOR • Crash type • Number of crashes • Property damage only + minor injury (B, C) • Number of A injuries or number killed (people) • Each incident is one crash
TOR Components • Estimated costs of deaths and injuries from U.S. National Safety Council (http://www.nsc.org/) • Estimated benefits resulting from reducing crashes • Traffic volumes • Reduction in fatalities and A injuries combined • Reduction in minor (no A injuries or fatalities) crashes
TOR Components • Q factor to blend the impact of fatalities and A injuries • Estimated project costs • Number of years of crash data used (3-5) • Area Factor - Urban, rural, and between
The Calculation • Roy Jorgensen's Formula BTOTAL = ADTa/ADTbx/ (QxR1+(PDOCOSTxR2)) • BTOTAL = Total benefit in dollars over years used • ADTa = Average traffic volume after the improvement (assumed) • ADTb = Average traffic volume before the improvement
The Calculation (Continued) • R1 = Reduction in fatalities and A-injuries combined • R2 = Reduction in minor (no A-injuries or fatalities) crashes • Q = [FATCOST+((I/FxINJCOST]/1+(I/F]
Summary • Michigan a has sound crash records system in place • Crash data, along with other safety data allow for problem identification, selection of treatments, and evaluation of implemented safety treatments • Crash data is essential to Michigan identifying strategic highway safety goals and monitoring safety performance • http://www.michigan.gov/tands