01099190

Component

Heavy left-turn movements can significantly impact the operational performance of signalized intersections. As a result, there has been considerable interest in alternative measures for dealing with left turns at intersections to improve performance, some of which have been unconventional schemes. One of these unconventional schemes, the Upstream Signalized Crossover (USC) intersection, was shown to significantly reduce average vehicle delays; particularly when the volumes entering the intersection are relatively high. More important, the capacity of the USC intersection was found to be approximately 50% greater than a conventional intersection with similar geometry under balanced traffic volumes. The Ministry of Public Works of Qatar is considering the implementation of the USC intersection on three signalized intersections along a major urban corridor in Doha. This paper investigates the potential improvements associated with the USC implementation. VISSIM was used to model and analyze the proposed three unconventional USC intersections as well as the existing conventional signalized intersections. Analyses were carried out for AM peak hour, mid-day peak hour, and PM peak hour. For each analysis period, the optimum cycle length and offsets were obtained for the USC and conventional intersections. The results showed that out of 26 travel time measurement sections, the number of sections that had lower delays in the USC configuration was 21, 20, and 18 for the AM peak, Midday peak, and the PM peak, respectively. All travel time sections that started from minor streets had lower delays in the USC configuration for all analysis periods. The analysis also showed that the total system delay, in hours, for the USC configuration was less than that of the conventional configuration by 19.4%, 14.8% and 13.6% for the AM peak, Midday peak, and PM peak, respectively. As well, the average control delay for the each single USC intersection was lower than its conventional counterpart by between 7.6% and 22.9%.

01084478

08-0921

English

20p

2008

Transportation Research Board 87th Annual Meeting

DVD

Figures; Photos; References (13) ; Tables (3)

Crossovers; Interchanges and intersections; Left turns; Operations; Peak hour traffic; Signalized intersections; Traffic characteristics; Traffic flow; Traffic volume; Turning traffic; Types of intersections

Administration and Management; Highways; Operations and Traffic Management; I73: Traffic Control

Transportation Research Board Annual Meeting 2008 Paper #08-0921

TRIS, TRB

Jan 29 2008 3:15PM