Optimization of time-of-day breakpoints based on improved NJW algorithm

In order to overcome the artificial arbitrariness on time-of-day breakpoints determination in traffic control and the defects of K-means method, spectral clustering algorithm was used to obtain the optimal time-of-day (TOD) breakpoints. Each phase's volume was selected as clustering data to reflect the system status as closely as possible and identify different traffic patterns in the dynamic traffic movements. The classic Ng-Jordan-Weiss (NJW) spectral clustering algorithm was improved to obtain an initial breakpoints, and then the final breakpoints at a given number of clusters were obtained after dealing with the outliers. After the best timing plans were obtained by Synchro software for each period, the best numbers of clusters was selected by simulation evaluation under different numbers of clusters using SimTraffic. And comparing with K-means method on simulation results, the proposed method contributed to a reduction of 6.8% in total delay and 5.4% in stops. ©, 2014, Zhejiang University. All right reserved.