Citation

Turner JM, Messer CJ. Transp. Res. Rec. 1978; 682: 58-64.

Copyright

(Copyright © 1978, Transportation Research Board, National Research Council, National Academy of Sciences USA, Publisher SAGE Publishing)

DOI

unavailable

PMID

unavailable

Abstract

Heavy ramp volumes on urban freeway frontage roads can cause operating problems at adjacent diamond interchanges if the spacing between the cross street and the ramps is not adequate. Spacing requirements from diamond interchanges were studied for both exit ramps and entrance ramps. Exit ramps should provide sufficient storage for the vehicles queued at the cross street as well as an adequate distance for the weaving and braking maneuvers performed by exiting vehicles. Entrance ramps should provide sufficient spacing to prevent queueing through the cross-street intersection. Studies were made on several Texas freeways to provide data to be used to determine spacing requirements. Volume and queue counts were conducted to determine realistic volumes. These studies were used to determine design criteria and to further justify the analytic exit- and entrance-ramp models presented.