Congested network flows: Time-varying demands and start-time policies

Abstract

This paper is concerned with modeling departure-time and arrival-time policies for flows on a congested network with time-varying demands. In particular, we are concerned with variation over a peak period, and for application we focus on modeling the morning rush-hour (the journey to work). We treat this as a multiple-origin, single-destination network model, the destination being the central business district. We use a system optimizing model, and allow the travel demands to vary with the cost (or price) of making a trip. The tradeoff between travel time and the cost of being early or late is considered for different work-start time policies, such as fixed work-start time and flex-time. For illustration, we apply the model to a simple network example and compare the congestion patterns and travel costs under each policy.