Departure time and route choice for the morning commute

Most theoretical studies of traffic congestion during the morning commute have been limited to one origin, one destination, and one route. This paper is the first to analyze systematically user equilibrium, system optimum, and various pricing régimes for a simple network of routes in parallel. Departure time and route decisions of commuters are assumed to be governed by the tradeoff between travel time and schedule delay (the difference between actual and desired arrival time). In equilibrium without tolls wasteful queuing occurs, although the numbers of drivers on each route is the same as in the system optimum. An optimal time-varying toll eliminates queuing without affecting route usage. Uniform and step tolls alter route usage, but only slightly. Step tolls generally yield much greater efficiency gains than uniform tolls because they reduce queuing by altering departure times.