Comparison of delay estimation models for signalised intersections using field observations in Shanghai

Vehicular control delay is important in evaluating the level of service and designing or adjusting the control schemes at signalised intersections. Although control delay may be obtained directly or indirectly nowadays for vehicles with global positioning system (GPS) or at locations with designated sensor types and configurations, such data are still not widely available. The analytical and empirical procedures for control delay estimation are still important, particularly in developing countries. However, very few studies explored the effectiveness of existing control delay estimation methods. This study intends to address this issue by comparing the delays estimated by four commonly adopted models using field data observed from three signalised intersections in Shanghai. Specifically, the study compares the delay estimates from deterministic queuing model, Webster model, highway capacity manual (HCM) 2000 model, and Shanghai adjusted model. The results indicate that HCM 2000 model and Shanghai adjusted model perform similarly and satisfactorily under various v / c ratios while deterministic queuing model has better performance when the v / c ratio is extremely high, but Webster model is mostly inadequate at coordinated signalised intersections. Meanwhile, signal progression, initial queue, proportion of vehicles arriving on green are found as main influential factors to the precision of models based on data analysis.