Optimized Advance Detector Configuration for Option Zone Protection at High-Speed Signalized Intersections

Advance detection and green extension schemes are widely applied in practice as a typical solution to the safety issues associated with the intersection dilemma zone problem. Most existing detector configurations either were based on the traditional Type I dilemma zone model, in which some critical contributing factors were assumed static, or were based on generic Type II dilemma zones. A comparison analysis based on field-observed trajectory data showed that the option zone model estimated the location of a dilemma zone most accurately of all available dilemma zone models. Recent research on the quantitative modeling of the contributing factors of the option zone made accurate identification of the option zone locations possible. Accurate identification lays a solid foundation for an option zone–based detection scheme for achieving the most effective and efficient dilemma zone protection. An alternative advance detector con-figuration is presented for option zone protection via optimization trials within a calibrated VISSIM simulation model. The optimization objective was to minimize the combined cost of dilemma hazard (safety) and delay (mobility). Dilemma conflict potential, a comprehensive dilemma hazard model, was used to measure the safety performance quantitatively and replaced the traditional measure of number of vehicles in the dilemma zone. The optimal configuration was evaluated and validated through its comparison with four widely applied detector configurations. The results revealed the superiority of the developed optimal detector configuration in terms of the best safety performance and the least combined cost of dilemma hazard and delay of all configurations.