Dynamic Holding Strategy to Prevent Buses from Bunching

This study proposed a robust dynamic control strategy to regulate bus headways and prevent buses from bunching by holding them at bus stops. The proposed strategy monitors bus locations in real time and estimates the time gaps between consecutive buses at a desired frequency. The holding times of all buses at their respective immediately downstream stops are determined simultaneously on the basis of the estimated time gaps. A procedure that consists of a discrete quadratic dynamic control program and a quadratic static optimization program was developed to produce a unique dynamic control law of holding times. Numerical investigations on an operational bus route revealed that the proposed strategy produced greater system reliability than did some existing control strategies and that the bus system under the control of the proposed strategy recovered promptly from large system disruptions.