Research Papers

Cell Phone Use and Traffic Crash Responsibility: A Culpability Analysis

Filename 3B-2-Mark-Asbridge.pdf
Filesize 144 KB
Version 1
Date added May 8, 2011
Downloaded 5 times/fois
Category 2011 CMRSC XXI Halifax
Tags Session 3B
Author/Auteur Mark Asbridge, Jeff Brubacher, Herbert Chan


Purpose: The use of a cell phone or communication device while driving is illegal in many jurisdictions. The evidence used to support these policies demonstrates that: i) cell phone use by motorists is on the rise, ii) a greater proportion of crashes appear to involve cell phone use, and iii) cell phone use negatively affects cognitive functions, visual fields, and reaction times, as well as overall driving performance. Only a handful of studies have evaluated the crash risk associated with cell phone use in naturalistic settings. These studies have found an increased crash risk associated with cell phone use, but most suffer from methodological flaws that include a lack of appropriate control groups and poor exposure measures that do not adequately capture cell phone use prior to the crash event. The current study aims to compare culpability in drivers who crashed while using a cell phone with those who did not use a cell phone. Culpability studies approximate case-control studies and overcome difficulties with constructing control groups (i.e. crash free drivers). The premise is that if cell phones increase crash risk, their use should be detected more often in culpable drivers.

Method: The Canadian Culpability Scale (CCS) was used to determine crash culpability from police reports drawn from the Insurance Corporation of British Columbia (ICBC) Traffic Accident System data. The CCS is an automated scale that accounts for Canadian driving conditions and agrees well with expert crash assessors (kappa =0.83). Culpability was assessed in 312 crashes in British Columbia (2005 – 08) where police reported cell phone use and in 936 matched (crash type, date, time of day, geographic location) crashes without cell phone use. Crashes where culpability was indeterminate (n=60) were removed from the analysis. Statistical analysis involved logistic regression methods to assess crude rates, with additional analyses to adjust for driver age, driver sex, graduated license status (novice driver or full license), police suspicion of alcohol or drug impairment, and interaction terms.

Results: A comparison of crashes with versus without cell phones revealed a crude odds ratio of 2.03 (95% CI: 1.44-2.86). This association remained after adjusting for age, sex, license status, and suspected alcohol or drug impairment (OR=1.82, 95% CI: 1.27-2.62), while sensitivity analysis demonstrated a consistent association regardless of crash severity. Younger drivers, novice drivers, and drivers suspected of alcohol or drug impairment also had significantly higher odds of a culpable crash. No significant interactions between cell phone use Conclusions: Crash culpability was found to be strongly associated with driver cell phone use. Drivers using cell phones had nearly double the odds of a culpable crash compared to those drivers who did not use a cell phone, lending much needed evidence to existing policies directed at restricting the use of cell phones and other devices while driving.

Mark Asbridge, Jeff Brubacher, Herbert Chan