Accident prediction models for traffic signals.

A significant proportion of urban crashes occur at traffic signals. Many of the black-spots in both Australia and New Zealand cities occur at high volume and/or high speed traffic signals. Major intersections often have long cycle times and complex phasing arrangements, which can confuse and frustrate drivers and pedestrians. Right turning phases are often introduced at traffic signals to reduce right-turn-against crashes, but this in turn increases cycle lengths and overall delays. Some traffic signals have unusual layouts, such as highly staggered right turn bays, which may cause safety problems. Crash prediction models have been produced, in several separate research projects for traffic signals, examining the impact of traffic volumes, speed limit, signal phasing, number of pedestrians and cyclists and intersection layout on various crash types. These crash prediction models have enabled a better understanding of the impact of these factors on safety and also allow the safety impact to be quantified. This paper summarises the outcomes of each of the separate studies and key findings of the research. (a) For the covering entry of this conference, please see ITRD abstract no. E217099.