Citation

Khatib ZK, Rouphail NM. Road Transp. Res. 2006; 15(1): 17-28.

Affiliation

Civil Engineering Department, College of Engineering, University of Sharjah, Sharjah, United Arab Emirates

Copyright

(Copyright © 2006, Australian Road Research Board)

DOI

unavailable

PMID

unavailable

Abstract

There is abundant research on methods for estimating the entry capacity for multilane roundabouts. However, very few if any observational studies included direct flow measurements at the boundary conditions, at which either the entry or circulating flow is at its maximum capacity rate. Moreover, the boundary conditions are where most capacity models appear to diverge significantly in their capacity estimates. In this paper, the boundary capacity conditions at a multilane roundabout in Sharjah, United Arab Emirates, were directly observed at each entry and circulating lane, and the results compared with the estimated capacity from several roundabout models widely used around the world. The study roundabout has three circulating lanes and two entry lanes on each approach. From observation, the maximum entry flow was calculated to be 1818 and 1644 veh/h for the left and right lanes respectively. The maximum circulating flow is 1498, 1758, and 731 veh/h for the inside, middle, and outside lanes respectively. The low flow (731 veh/h) on the outside circulating lane is an apparent indication of different lane utilisation. It was also found that of all the models tested, the Australian gap-acceptance model provided the best estimates for multilane roundabout maximum entry and circulating flows, and that improved capacity estimates were achieved when the gap-acceptance models used local parameter estimates.

Language: en