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Development of crash modification factors for changing lane width on roadway segments using generalized nonlinear
Chris Lee1, Mohamed Abdel-Aty2, Juneyoung Park2
1Department of Civil and Environmental Engineering, University of Windsor, ON N9B 3P4, Canada.
Accident; Analysis and Prevention
|January 24, 2015
Summary
This study found that roadway crash rates are highest for 12-ft lanes. Generalized nonlinear models (GNMs) reveal that narrower or wider lanes can reduce crashes, especially at higher speeds.
Area of Science:
- Road safety
- Traffic engineering
- Statistical modeling
Background:
- Roadway segment safety is crucial for reducing traffic accidents.
- Lane width is a significant geometric factor influencing crash frequency.
- Existing models often fail to capture the nonlinear relationship between lane width and crash rates.
Purpose of the Study:
- To evaluate the effectiveness of varying lane widths in reducing roadway segment crashes.
- To develop and apply generalized nonlinear models (GNMs) for analyzing crash data.
- To estimate crash modification factors (CMFs) for different lane width scenarios.
Main Methods:
- Utilized 3-year crash records and road geometry data from Florida roadway segments.
- Developed generalized nonlinear models (GNMs) to account for nonlinear crash rate-lane width relationships.
- Estimated crash modification factors (CMFs) for various lane width ranges using GNM outputs.
Main Results:
- Crash rates were highest for 12-ft lanes, decreasing for widths above or below 12 ft.
- GNMs effectively extrapolated the continuous nonlinear effect of lane width on crash rates.
- CMFs indicated reduced crash likelihood for lanes <12 ft (if speed ≥40 mph) and for lanes >12 ft.
- Higher severity crashes (KABC, KAB) were less likely with lane widths deviating from 12 ft.
Conclusions:
- GNMs provide a more accurate representation of the nonlinear relationship between lane width and crash rates compared to traditional GLMs.
- Lane width adjustments, particularly deviations from 12 ft, can significantly reduce crash frequency and severity.
- The interaction between lane width and speed limit is a critical factor influencing crash modification effectiveness.
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