Iterative Quadratic Optimization for the Bus Holding Control Problem

A multiple control-point strategy for holding control of a bus transit system is presented. The model developed is deterministic and assumes the availability of real-time information and historical data of the system. Stochastic effects are disturbances to be compensated by the feedback nature of the control. The objective is to minimize total user delay, which is modeled by a nonconvex cost function and nonlinear constraints. To efficiently solve the problem, simplifications of the original model are introduced, together with an iterative quadratic programming (IQP) optimization procedure. A numerical example illustrates the application of the method, indicating its feasibility for real-time applications and the good approximation of the global optimum provided by the heuristic solution.