01624322

Component

https://doi.org/10.3141/2635-09

The Highway Safety Manual (HSM) provides guidance on the application of crash prediction models for network screening, evaluation of alternative designs, and evaluation of implemented safety improvements. A variety of models are available. They may be classified as network screening level (or simple models), project level [or crash modification factor (CMF)–corrected models], and evaluation-level models. The use of crash prediction models to identify sites with promise of safety improvement is often based on assessing the difference between the expected number of crashes (Ne) at a site and the predicted number of crashes (Np) for similar sites within the population. A large difference between Ne and Np may denote a safety problem and be used to identify and rank sites with promise. The HSM indicates that CMF-corrected models may be used for network screening purposes. However, issues arise in the analysis regarding the definition of similar sites. When CMF-corrected models are used, the definition of similar sites changes with changes in the CMF adjustments particular to each site. Use of (Ne – Np) for identifying and ranking sites with promise does not work well when the analysis uses a CMF-corrected estimate of Np. A large combined CMF will increase Np and thereby decrease the value (Ne – Np). But a large combined CMF may point to a site with promise. This paper examines this phenomenon in detail, reviews a case study, and suggests that simple models may be preferable for identifying sites with promise.

01631075

17-02245

English

pp 71–78

2017

Transportation Research Record: Journal of the Transportation Research Board

9780309441612

Digital/other

Figures (6) ; Maps; References (13) ; Tables (2)

Crash data; Crash modification factors; High risk locations; Mathematical models; Mathematical prediction

Data and Information Technology; Highways; Safety and Human Factors

PRP, TRIS, TRB, ATRI

Dec 8 2016 10:50AM

• Application of an Intelligent Transportation System in a Travel Time Information System: Safety Assessment and Management
• Developing a Web-Based Tool to Track Highway Safety Planning Progress in California
• Geographic Information System–Based Spatial and Statistical Analysis of Severe Crash Hotspot Accessibility to Hospitals
• Implementation of Active Traffic Management Strategies for Safety on Congested Expressway Weaving Segments
• Improving the Self-Explaining Performance of Czech National Roads
• Multiobjective Evaluation in Countermeasure Selection at Two-Way Stop-Controlled Intersections: Considering Traffic Operation, Safety, and Environment
• Probability of Secondary Crash Occurrence on Freeways with the Use of Private-Sector Speed Data
• Roadway Safety Policy and Leadership: Case Study of Six Midwest States
• Trend Analyses of Emergency Medical Services for Motor Vehicle Crashes: Michigan Case Study
• Understanding Traffic Safety Culture: Implications for Increasing Traffic Safety