Signal timing estimation using point detectors

Compared with the traffic flows on freeways, the traffic in urban networks is significantly influenced by signal controls. Therefore, signal timing parameters are required in lots of urban research topics, including signal performance measurements and traffic control methods. However, direct access to signal timing information is prohibitively difficult due to the diversities in signal machines and signal schemes. The objective of this paper is to demonstrate the feasibility of estimating signal timing parameters using point detectors. We use the passing timestamps obtained from ANPR cameras as an example data source. Firstly, a robust method is proposed to determine whether a new cycle starts by recognizing cycle breaking vehicles. Then cycle times, starts of greens, and changes in signal schedules are deduced by analyzing the periodic features of cycle breaking vehicles. Finally, a sensitivity analysis is carried out to show the influence of penetration rates.