Some Issues Relating to Metering or Closing of Freeway Ramps Part II. Translationally Symmetric Corridor.

As an idealization of a long freeway imbedded in a network of parallel streets, we consider a hypothetical freeway with equally spaced entrance and exit ramps joining an adjacent slower speed parallel route. The origin-destination pattern of trips is assumed to be translationally symmetric on the adjacent route. Each ramp can be metered (causing a queue to form), closed, or left uncontrolled. Two extreme strategies are considered. In the first, the ramps have a spacing short compared with the average trip length, but all ramps are metered at the same rate. In the second, the spacing between ramps is adjusted by closing ramps, but those which are open are not metered. Flow on the freeway is reduced because travelers will (on the average) travel a certain fraction of their journey on the alternate route, enroute to a ramp. The latter strategy typically gives a lower total travel cost, for flows on the freeway close to its capacity. [ABSTRACT FROM AUTHOR]