Development of crash modification factors for changing lane width on roadway segments using generalized nonlinear models

Chris Lee; Mohamed Abdel-Aty; Juneyoung Park; Jung-Han Wang

doi:10.1016/j.aap.2015.01.007

Development of crash modification factors for changing lane width on roadway segments using generalized nonlinear models

Accid Anal Prev. 2015 Mar:76:83-91. doi: 10.1016/j.aap.2015.01.007. Epub 2015 Jan 20.

Authors

Chris Lee¹, Mohamed Abdel-Aty², Juneyoung Park³, Jung-Han Wang⁴

Affiliations

¹ Department of Civil and Environmental Engineering, University of Windsor, ON N9B 3P4, Canada. Electronic address: cclee@uwindsor.ca.
² Department of Civil, Environmental and Construction Engineering, University of Central Florida, Orlando, FL 32816-2450, USA. Electronic address: m.aty@ucf.edu.
³ Department of Civil, Environmental and Construction Engineering, University of Central Florida, Orlando, FL 32816-2450, USA. Electronic address: jypark@knights.ucf.edu.
⁴ Department of Civil, Environmental and Construction Engineering, University of Central Florida, Orlando, FL 32816-2450, USA. Electronic address: jwang@knights.ucf.edu.

PMID: 25616033
DOI: 10.1016/j.aap.2015.01.007

Abstract

This study evaluates the effectiveness of changing lane width in reducing crashes on roadway segments. To consider nonlinear relationships between crash rate and lane width, the study develops generalized nonlinear models (GNMs) using 3-years crash records and road geometry data collected for all roadway segments in Florida. The study also estimates various crash modification factors (CMFs) for different ranges of lane width based on the results of the GNMs. It was found that the crash rate was highest for 12-ft lane and lower for the lane width less than or greater than 12ft. GNMs can extrapolate this nonlinear continuous effect of lane width and estimate the CMFs for any lane width, not only selected lane widths, unlike generalized linear models (GLMs) with categorical variables. The CMFs estimated using GNMs reflect that crashes are less likely to occur for narrower lanes if the lane width is less than 12ft whereas crashes are less likely to occur for wider lanes if the lane width is greater than 12ft. However, these effects varied with the posted speed limits as the effect of interaction between lane width and speed limit was significant. The estimated CMFs show that crashes are less likely to occur for lane widths less than 12ft than the lane widths greater than 12ft if the speed limit is higher than or equal to 40mph. It was also found from the CMFs that crashes at higher severity levels (KABC and KAB) are less likely to occur for lane widths greater or less than 12ft compared to 12-ft lane. The study demonstrates that the CMFs estimated using GNMs clearly reflect variations in crashes with lane width, which cannot be captured by the CMFs estimated using GLMs. Thus, it is recommended that if the relationship between crash rate and lane width is nonlinear, the CMFs are estimated using GNMs.

Keywords: Crash modification factor; Generalized nonlinear model; Lane width; Roadway segment; Speed limit.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Acceleration / adverse effects
Accidents, Traffic / prevention & control*
Accidents, Traffic / statistics & numerical data
Cross-Sectional Studies
Distance Perception
Environment Design*
Florida
Humans
Nonlinear Dynamics*
Orientation
Safety
Statistics as Topic