Method for dynamic measuring of delay at unsaturated signalized intersections

The typical problems of emerging methods based on detector data for measuring delay at urban signalized intersections such as input hypothesis, model establishment and fault-tolerance performance were pointed out. A new method named "sampling population" which useed two rows of detectors for dynamic survey of approach delay by the signal cycle at unsaturated intersections was put forward, including the process of cycle split, the arrival time of the first car and the departure time of the last car at exit detectors, the upper and lower boundary of input gap at entrance detectors, and corresponding method for approach delay measuring. Finally, two case studies were made in Shanghai (Cao'an-Qilianshan intersection and Wuning-Daduhe intersection, including 37 cycles and 1565 vehicles) to verify the accuracy of the proposed method. The results show that mean absolute error (MAE) of the measurement delay is 4.1 seconds under no detector error compared to 0.1 seconds fewer than 95% detector accuracy. The method is insensitive to the detector error, and can be used to provide the accurate, timely and reliable delay index for traffic control system.