Citation

Shortreed JH. Transp. Res. Rec. 1984; 971: 14-20.

Copyright

(Copyright © 1984, Transportation Research Board, National Research Council, National Academy of Sciences USA, Publisher SAGE Publishing)

DOI

unavailable

PMID

unavailable

Abstract

A study of intersection signal optimization in a medium-sized city indicated that there were a large number of approaches without an exclusive left-turn lane, but rather with a shared left and through lane. The study also found that the accurate determination of the capacity of a shared left-turn lane was critical to the analysis of intersection performance. Moreover a search of the literature suggested that there are no current methods of estimating the capacity of an approach containing a shared left-turn lane. A method is proposed for estimating the capacity of a shared left-turn lane. The method builds on the existing procedures for exclusive left-turn lanes first developed by the British in 1966 and since extended in Australia and the United States. The proposed method develops an estimate of the flow of through vehicles during the initial part of the green display when left-turn vehicles are blocked by the opposing flow. Subsequent gap acceptance behavior is modeled to reflect the length of the displayed-green time. Finally, the flow after green is modified to reflect the probability of the shared left-turn lane actually being blocked when the green ends. The resulting capacities compare favorably with results quoted in the literature for cases where conditions in a shared left-turn lane are similar to those in an exclusive left-turn lane situation. The results are given both in tabular form and as a set of iterative equations.

Record URL:
http://onlinepubs.trb.org/Onlinepubs/trr/1984/971/971-003.pdf

Language: en

Keywords

ROADS AND STREETS; HIGHWAY ENGINEERING; STREET TRAFFIC CONTROL