Citation

Ovaici K, Teal RF, Ray JK, May AD. Transp. Res. Rec. 1975; 533: 122-137.

Copyright

(Copyright © 1975, Transportation Research Board, National Research Council, National Academy of Sciences USA, Publisher SAGE Publishing)

DOI

unavailable

PMID

unavailable

Abstract

This paper describes the development and application of an analytical procedure for priority-entry-control strategies at freeway ramps. Vehicles with different numbers of occupants arriving at an on-ramp are differentiated, and and those vehicles with more occupants are given priority entry onto the freeway. The 2 primary objectives of the priority-control strategy are to maximize either the number of persons served or the number of passenger-miles traveled. The primary constraint is that the vehicular demand for each freeway section not exceed the vehicular capacity of that freeway section. Additional constraints such as maximum and minimum metering rates can be specified. The analytical procedure encompasses 2 models. The first is a simulation model that is deterministic and macroscopic and predicts freeway-traffic performance as a function of freeway design and allowable ramp inflows. The second is a decision model that has a linear programming formulation and selects a control strategy that meets specified objectives and constraints. The simulation model has been validated under field conditions, and the predicted traffic performance compares favorably to actual, measured traffic performance. The 3 models have been integrated and the composite model has been applied to the East Bayshore Freeway in the San Francisco Bay area, the Santa Monica Freeway in Los Angeles, and the Long Island Expressway to demonstrate its application and to provide the California Department of Transportation and the New York State Department of Transportation with results that could be considered for possible implementation. A series of investigations were undertaken with the computerized model to determine the sensitivity of the overall measures of effectiveness to practical constraints and to consider the consequences of such control strategies on changing the traffic-demand pattern and passenger-car occupancy distributions.