Some Issues Relating to Metering or Closing of Freeway Ramps Part I. Control of a Single Ramp

A hypothetical transportation corridor consists of two parallel routes. One route has properties typical of a congested freeway, the other is considered to be the composite of all alternative routes on city streets. Transfer between the two routes is permitted only at discrete points entrance or exit ramps. At these points, various methods of traffic control are possible. It is postulated that the control objective is to minimize the total cost of travel to all trips, subject to the hypothesis that travelers choose the route of minimum personal cost. Emphasis is placed on two control methods; metering the flow at entrance ramps, or closing the ramps. Two specific models are considered. In this study Part I, backtracking is forbidden but the origin-destination characteristics are fairly general. In a second study Part II, backtracking is permitted but the origin-destination characteristics have translational symmetry. In both cases it is found that, if the queuing costs are included in the total travel cost, ramp closure is often a more efficient method of control than ramp metering.