Queuing delay models for single-lane roundabouts†

^†The views expressed in this paper are those of the authors and do not reflect the official policy or position of the United States Air Force, Department of Defense or the US Government.

Abstract

This article presents an analytical model for a few important operational characteristics of single-lane roundabouts in the United States. In particular, we obtain renewal-based analytical expressions for the mean and variance of the time required for entry into the circulating stream for an arbitrary vehicle occupying the first position of the approach, regardless of the distribution of time headways for the circulating stream. These analytical models are subsequently applied in a M/G/1 queuing model to compute the steady-state average delay and length of the queue at the approach under stable conditions. The analytical models are validated by comparing numerical results for average delay with field observations obtained at six single-lane roundabout sites in the United States. The models are shown to perform well under a range of circulating stream flow rates.

^†The views expressed in this paper are those of the authors and do not reflect the official policy or position of the United States Air Force, Department of Defense or the US Government.

Keywords:

• Roundabout operations
• Roundabout delay
• Headway distribution
• Delay
• Unsignalized operations

Notes

^†The views expressed in this paper are those of the authors and do not reflect the official policy or position of the United States Air Force, Department of Defense or the US Government.