Effect of countdown timers on red light violations under heterogeneous traffic conditions

The expectation with which timers are installed at signals is that they will reduce lost times, delays and accidents. However, studies which analysed the correctness of these assumptions on the effectiveness of timers by systematic analysis are very limited and none of them were from Indian traffic conditions. Present study is an attempt in this direction to study the effect of timers on red light violations (RLV). This study was carried out using video data collected at a four legged signalized intersection in Chennai, with and without timer. Classified violations were counted at the start and end of red, for every signal cycle. The data is analyzed and the effect of various parameters on RLV was evaluated and a model was developed. The results indicated that, contrary to expectation, the over all number of violations is increasing with the presence of timer. Also, this increase in RLVs was observed to happen at the end of red. Overall, the study sheds light on the nature of red light violations with respect to timer presence, and can be useful for decision makers on the effectiveness of installing timers at intersections.