Urban traffic control — A general approach

An online control policy is presented using hierarchical control theory. It is shown that delays and stops are related to fuel consumption and exhaust emission rate. It is also shown that exhaust emission rate is related to fuel consumption in terms of the control variables cycle time, green time, and the relative offset. A general criterion is presented by which any of the functions of stops, delays, fuel consumption, or exhaust rate emission can be minimized. A complete mathematical description of the control system structure, software, and algorithms of control is given. The algorithms for the control parameters are given mathematically to cover the range of criterion function. All decision sets are evaluated and a procedure for the control policy is described. This online policy has the ability to adjust itself to suit the traffic variation in real time due to its prediction principle and also of selecting the desired function of minimization of stops, delays, fuel consumption, or exhaust emission rate for the whole network or subareas within the network.