Research Papers

An evaluation of Winnipeg's Photo Enforcement Safety Program: Results of time series analyses and an intersection camera experiment

Filename FINAL-PAPER-83.doc
Filesize 802 KB
Version 1
Date added June 10, 2012
Downloaded 3 times/fois
Category 2012 CMRSC XXII Banff
Tags Session 6A
Author/Auteur Ward Vanlaar, Robyn Robertson, Kyla Marcoux


Purpose: The objective of this study was to evaluate the impact of Winnipeg's photo enforcement safety program on speeding and red-light running behaviour as well as on crashes resulting from these behaviours.

Method: ARIMA time series analyses regarding crashes related to red-light running (right-angle crashes and rear-end crashes) and crashes related to speeding (injury crashes and property damage only crashes) occurring at intersections were conducted using monthly crash counts from 1994 to 2008. A quasi-experimental intersection camera experiment was also conducted using roadside data on speeding and red-light running behaviour. These data were analyzed using logistic regression analysis.

Results: The time series analyses showed that for crashes related to red-light running, there had been a 46% decrease in right-angle crashes at camera intersections, but that there had also been an initial 42% increase, followed by a 19% decrease in rear-end crashes. For crashes related to speeding, analyses revealed that the installation of cameras was associated with a 24% decrease in injury crashes and a 13% decrease in property damage only (PDO) crashes at camera intersections and a 2% increase in PDO crashes at other intersections without cameras. Results of the intersection camera experiment show that there were significantly fewer red light running violations after installation of cameras and that photo enforcement had a protective effect on speeding behaviour. However, the data also suggest photo enforcement may be more effective in preventing serious speeding violations.

Conclusions: Overall, it appears the photo enforcement safety program had a positive net effect on traffic safety in the city of Winnipeg. With regards to the time series analyses of crashes related to red light running, the finding of an initial increase in rear-end crashes followed by a decrease suggests that drivers soon adjusted their behaviour to the presence of cameras and this then led to a subsequent decrease in rear-end crashes. Given the positive impact of intersection cameras on right-angle crashes, these analyses show the benefits of using photo enforcement. However, mitigating strategies are needed to prevent a possible increase in rear-end crashes. Regarding speeding related crashes, the time series analyses also revealed that installation of photo enforcement cameras had a positive impact. The intersection camera experiment clearly shows the benefits of using photo enforcement with significantly fewer red-light running violations after installation of cameras. As for speeding violations, the data suggest that photo enforcement is more effective in preventing speeding violations in general but may be less effective in preventing serious speeding violations. Further research is needed to study the effects on different types of drivers and to identify the impact of intersection design in an effort to enhance our understanding of how best to implement photo enforcement. Further research is also needed to shed light on what particular aspects of the program are effective and how it can best be improved.

Ward Vanlaar, Robyn Robertson, Kyla Marcoux