Before-After Study Using Chicago Crash Data Estimated 12 Percent Reduction in Injury Crashes with Automated Speed Camera Enforcement.
Automated Speed Camera Enforcement in Chicago was Evaluated for Safety Improvement.
Chicago, Illinois, United States
Safety Impact of Automated Speed Camera Enforcement: Empirical Findings Based on Chicago’s Speed Cameras
Summary Information
Automated speed camera enforcement is used by transportation agencies to reduce speeding and improve roadway safety. This study evaluated the effectiveness of automated speed cameras installed in the 2013 to 2014 period in Chicago, Illinois, in reducing injury crashes and fatalities. A before-after study was conducted by taking the 2010 to 2012 period as the before treatment period and the 2015 to 2017 period as the post treatment period and focusing on all injury and fatality crashes that occurred within a 250 meters (820 feet) buffer of the cameras on the instrumented road at 101 camera locations.
METHODOLOGY
In this study, the empirical Bayes (EB) method was used by identifying similarly treatable, but untreated, road segments to evaluate the safety performance of roadways in safety zones. An initial set of 300 points was randomly placed on these road segments to represent treatable sites. These points were then matched with treated locations using propensity scores, based on factors such as annual average daily traffic (AADT) and the number of driveways within a 250 meter buffer on either side of each randomly placed point. This process matched 101 locations.
FINDINGS
- This study estimated a 12 percent reduction in injury crashes across treated locations included in the analysis.
- Results also indicated that fatality and severe injury crashes declined by 15 percent.
