Development of a Timed Coloured Petri Net Model for Time-of-Day Signal Timing Plan Transitions

In many countries, traffic signal control is one of the most cost effective means of improving urban mobility. Nevertheless, the signal control can be grouped into two principal classes, namely traffic-response and fixed-time. Precisely, a traffic response signal controller changes timing plan in real time according to traffic conditions while a fixed-time signal controller deploys multiple signal timing plans to cater for traffic demand changes during a day. To handle different traffic scenarios via fixed-time signal controls, traffic engineers determine such time-of-day intervals manually using one or two days worth of traffic data. That is, owing to significant variation in traffic volumes, the efficient use of fixed-time signal controllers depends primarily on selecting a number of signal timing plans within a day. In this paper, a Timed Coloured Petri Net (TCPN) formalism was explored to model transition between four signal timing plans of a traffic light control system such that a morning peak signal timing plan handles traffic demand between the hours of 6:00 am and 8:30 am, followed by afternoon I and afternoon II signal timing plans which handle traffic demands from 8:30 am to 3:00 pm and from 3:00 pm to 7:00 pm respectively, while the off peak plan handles traffic demands from 7:00 pm to 9:00 pm. Other hours of the day are ignored since they are characterized by low traffic demands. Keywords: Signal timing plan, Petri nets, Time-of-day, Model, Traffic, Fixed-time