Citation

Behnood A, Mannering FL. Traffic Injury Prev. 2017; 18(5): 456-462.

Affiliation

Department of Civil and Environmental Engineering, University of South Florida, 4202 E Fowler Avenue, ENC 3300 , Tampa , FL 33620 , USA , E-mail: flm@usf.edu.

Copyright

(Copyright © 2017, Informa - Taylor and Francis Group)

DOI

10.1080/15389588.2016.1262540

PMID

27893281

Abstract

OBJECTIVE: It is well known that alcohol and drugs influence driving behavior by affecting the central nervous system, awareness, vision, and perception/reaction times, but the resulting effect driver-injuries in car crashes is not fully understood. The purpose of this study was to identify factors affecting the injury severities of unimpaired, alcohol-impaired and drug-impaired drivers Method: The current paper applies a random parameters logit model to study the differences in injury severities among unimpaired, alcohol-impaired and drug-impaired drivers. Using data from single-vehicle crashes in Cook County Illinois over a nine-year period from January 1, 2004 to December 31, 2012, separate models for unimpaired, alcohol-impaired and drug-impaired drivers were estimated. A wide range of variables potentially affecting driver-injury severity was considered including roadway and environmental conditions, driver attributes, time and location of the crash, and crash-specific factors.

RESULTS: The estimation results show significant differences in the determinants of driver injury severities across groups of unimpaired, alcohol-impaired and drug-impaired drivers. The findings also show that unimpaired drivers are understandably more responsive to variations in lighting, adverse weather and road conditions, but these drivers also tend to have much more heterogeneity in their behavioral responses to these conditions, relative to impaired drivers. In addition, age and gender were found to be important determinants of injury severity, but the effects varied significantly across all drivers, particularly among alcohol-impaired drivers.

CONCLUSIONS: The model estimation results show that statistically significant differences exist in driver-injury severities among the unimpaired, alcohol-impaired, and drug-impaired driver groups considered. Specifically, we find that unimpaired drivers tend to have more heterogeneity in their injury outcomes in the presence potentially adverse weather and road-surface conditions. This makes sense because one would expect unimpaired drivers to apply their full knowledge/judgment range to deal with these conditions, and the variability of this range across the driver population (with different driving experiences, etc.) should be great. In contrast we find, for the most part, that alcohol-impaired and drug-impaired drivers have far less heterogeneity in the factors that affect injury severity, suggesting an equalizing effect resulting from the decision-impairing substance.

Language: en