Real-time Signal Timing Optimization

Today engineers see retiming of traffic signals as one of the most cost effective methods of improving traffic flow. Traffic flow improvements of up to 26% have been reported by retiming traffic signals. Conventionally signal timing is optimized for traffic volumes at the various approaches of an intersection. The problem with this is that, over time the traffic volumes change and the signal timing has to be changed frequently to account for this.  If DSRC is widely deployed, one of the obvious things that can be done is the replacement of loop and video detectors at intersections with DSRC transceivers. A vehicle can check-in with an intersection as soon as it reaches within range of the intersection. We can also increase the range of detection by placing DSRC receivers along the roadway if desired. Using DSRC transceivers will eliminate most of the issues of the current loop detectors and also will provide us with additional data like traffic volumes, turn volumes etc.  If we link all the DSRC units in the vehicles with a GPS system we can also get route information, lane occupancy etc., which can be further used to improve the efficiency of the network. Presently signal timing is done using historical data with a slice of the cycle time allotted to each phase. Although, the usage of various vehicle detectors has allowed us to optimize this further, time is still wasted in many situations. Most signals cannot handle unexpected spikes in traffic volumes caused by accidents or a public event like a game of football. Real time signal timing optimization can be done at various levels, some of which are explained below. The idea is presented in a very broad sense and no technical details are involved.