01020089

Component

https://doi.org/10.3141/1988-05

http://scholar.google.com...logg&publication_year=2006

The current model used in the United States to predict approach capacity at a single-lane roundabout uses information about entry driver behavior in response to the circulating traffic stream only. There is no procedure for including exiting vehicles in capacity estimation. Exiting vehicles are vehicles that leave the circulating stream of traffic by maneuvering into the exit lane at a roundabout approach. Exiting vehicles are known to have an effect on capacity at roundabout approaches in other countries, but their effect in the United States is not known. The purpose of this research is to determine whether including exiting vehicles improves capacity estimation at a roundabout approach. An exploration of the relationships of the proportion of exiting vehicles and the width of the splitter island to approach capacities is included. Capacities were estimated both with and without exiting vehicles as part of the conflicting flow and compared with measured field capacities. The findings demonstrate that capacity estimates with exiting vehicles result in improved prediction of the actual capacity of a roundabout approach over estimates without exiting vehicles. The proportion of exiting vehicles in the major stream and the width of the splitter island appear to provide some benefit in capacity prediction, but exactly how these parameters can be incorporated into the capacity prediction process must be further explored.

01042128

English

pp 23-30

2006

Transportation Research Record: Journal of the Transportation Research Board

0309099986

Print

Figures (9) ; References (7) ; Tables (2)

Approach lanes; Estimating; Highway capacity; Mathematical prediction; Roundabouts; Traffic flow

Highway Capacity Manual

Exiting vehicles; Roundabout approach; Roundabout capacity

United States

Data and Information Technology; Highways; Operations and Traffic Management; I71: Traffic Theory

TRIS, TRB

Mar 3 2006 10:59AM

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