Control Strategies For Transit Priority: Comparing Adaptive Priority With Full Transit Signal Priority

A new logic based adaptive transit signal priority (TSP) control with double detection is developed and compared with full priority for mixed lane conditions (i.e. no exclusive bus lane). A sensitivity analysis is done for different intersection flow ratios for comparing the impact on person and vehicle delay. Also the impact of a transit stop is analysed on the performance of the system. The results suggest that the choice of a TSP strategy is depending on the intersection flow ratio, the presence of a travel time disturbance, and the weights of the performance function. Adaptive TSP is preferred in undersaturated conditions because of the flexibility of redistribution green times without going to oversaturation and is better able to minimize transit delay. If intersection flow ratios increase and the intersection gets saturated the favour shifts to full priority with a short distance detector (150m). Results also show that travel time disturbances shift the favour towards a TSP strategy with a detector beyond the disturbances. This implies that travel time reliability for arrival prediction of transit vehicles is a key factor in the choice of TSP strategy and detector location.