Study Details

Study Title: Are multiple speed cameras more effective than a single one? Causal analysis of the safety impacts of multiple speed cameras

Authors: Li et al.

Publication Date: MAY, 2020

Abstract: Most previous studies investigate the safety effects of a single speed camera, ignoring the potential impacts from adjacent speed cameras. The mutual influence between two or even more adjacent speed cameras is a relevant attribute worth taking into account when evaluating the safety impacts of speed cameras. This paper investigates the safety effects of two or more speed cameras observed within a specific radius which are defined as multiple speed cameras. A total of 464 speed cameras at treated sites and 3119 control sites are observed and related to road traffic accident data from 1999 to 2007. The effects of multiple speed cameras are evaluated using pairwise comparisons between treatment units with different doses based on the propensity score methods. The spatial effect of multiple speed cameras is investigated by testing various radii. There are two major findings in this study. First, sites with multiple speed cameras perform better in reducing the absolute number of road accidents than those with a single camera. Second, speed camera sites are found to be most effective with a radius of 200 m. For a radius of 200 m and 300 m, the reduction in the personal injury collisions by multiple speed cameras are 21.4 % and 13.2 % more than a single camera. Our results also suggest that multiple speed cameras are effective within a small radius (200 m and 300 m).

Study Citation: Li, H., M. Zhu, D.J. Graham, and Y. Zhang. "Are multiple speed cameras more effective than a single one? Causal analysis of the safety impacts of multiple speed cameras". Accident Analysis and Prevention, Vol. 139, (2020).

Study Report: Download the Study Report Document


CMFs Associated With This Study

Category: Advanced technology and ITS

Countermeasure: Implement automated speed enforcement cameras

CMF CRF(%) Quality Crash Type Crash Severity Roadway Type Area Type
0.85 14.97 4 Stars All K,A,B,C All All
0.854 14.62 4 Stars All K,A,B,C All All
0.856 14.37 4 Stars All K,A,B,C All All
0.863 13.65 4 Stars All K,A,B,C All All
0.879 12.13 4 Stars All K,A,B,C All All
0.936 6.38 4 Stars All K,A,B,C All All
0.654 34.63 4 Stars All K,A,B,C All All
0.802 19.77 4 Stars All K,A,B,C All All
0.878 12.18 4 Stars All K,A,B,C All All
0.905 9.49 4 Stars All K,A,B,C All All
0.935 6.54 4 Stars All K,A,B,C All All
0.957 4.27 4 Stars All K,A,B,C All All
0.786 21.44 4 Stars All K,A,B,C All All
0.868 13.23 4 Stars All K,A,B,C All All
0.901 9.94 4 Stars All K,A,B,C All All
0.982 1.84 4 Stars All K,A,B,C All All