Evaluation of Effectiveness of Red Light Camera Programme in Perth
A study was undertaken to evaluate effects of red light camera installations at 58 Perth metropolitan intersections. The cameras had been installed over the period between 1984 and 1998.
The effects of the presence of cameras were estimated in terms of cost of crashes and number of crashes, by comparing the number and cost of crashes ?before? against the number and cost of crashes ?after? the installation of red light cameras, over the same length of time. Periods of observation for the intersection sites varied depending on the date of installation and availability of crash data. The crash data by intersection were extracted from the database covering the period between 1980 and 1999. Observation periods ranged between 1 and 9.5 years, with the mean of 5 years. The estimates of camera effects were based on crash data collected over 292.7 camera-years of system installations/operations at the sample of intersection locations.
Two approaches were considered in estimating effects of cameras on crash occurrence at the intersections: (a) differences in cost and frequency of all crashes at the sample of intersections; and (b) differences in cost and frequency of crashes involving vehicles that might have run a red light on the approaching leg in the direction of the red light camera. These cost and crash frequency differences were adjusted using average annual change in cost and frequency of crashes at a control sample of 447 signalised intersections that had been in operation since 1985.
The results of the study indicated that installation of red light cameras together with camera signage has a significant effect on severity and occurrence of types of crashes. For all intersection crashes, it was shown that ?after? period experienced over 50% reduction in fatal crashes, mostly accounted for by right turn against (71%) and other types of crashes (67%). The ?after? period, when adjusted for differences at the control intersections, resulted in reduction of: right turn against (21%), right angle (30%) and other types of crashes (18%), while rear end crashes increased by 17% compared to the period ?before?. Reduction in the total number of crashes was negligible, 3%.
Analysis by road user movement suggested that largest reductions in the types and severity of crashes were associated with the vehicle movements in the camera direction. These movements accounted for 73% of the reduction in fatal crashes, mainly explained by right turn against (86%) and right angle crashes (50%). It was estimated that the 11% reduction in all right turn against crashes and the 18% reduction in all right angle crashes were explained by crashes involving vehicles travelling on one of the movements in the camera direction.
Road user movements other than those involving movements in the camera direction experienced similar reductions/increases in types of crashes. In addition, the study found a significantly positive correlation between average number of red light running infringements and total number of crashes, before and after installation of red light cameras, mainly accounted for by rear end and crashes other than right angle or right turn against crashes. These findings suggest that red light camera installation on an intersection, supported with signage, has a significant effect on occurrence of all types of crashes rather than only those that might have been associated with red light running.
It is estimated that the camera installation system at a location, on average, results in a reduction in the cost of crashes of $52,000 per year.