Citation

Gluck JS, Haas GL, Mahmood J, Levinson H. Transp. Res. Circular 2000; (E C019): 17 p..

Copyright

(Copyright © 2000, U.S. National Academy of Sciences Transportation Research Board)

DOI

unavailable

PMID

unavailable

Abstract

This paper reviews research studies relating traffic operations to access spacing, presents results of specially conducted operations analyses at 22 sites in Connecticut, Illinois, New Jersey, and New York, and sets forth emergent access spacing guidelines. The literature review and operational analyses were performed as part of NCHRP Project 3-52 -- Impacts of Access Management Techniques. Each site represented an unsignalized driveway for a major traffic generator along a suburban arterial roadway without deceleration lanes. Information was gathered on the number and percentage of through vehicles impacted by right turns. The percentage of through vehicles impacted approximated 0.18 times the right-turn volumes. The impact lengths of through vehicles were determined, and the influence distances were computed. The results were then used to quantify the likely effects of multiple driveways and to establish guidelines for deceleration lanes and access separation distances. Access separation distances for various operating speeds and right-turn volumes were based on the likelihood of minimizing spillback across an upstream driveway over a series of driveways along a 1/4-mile section of road. For example, to hold the spillback rate to 20% for a 40-mph posted speed, a 285-ft spacing would be needed. When the acceptable spillback rate is reduced to 5%, a 400-ft separation is required.