A Roundabout Case Study Comparing Capacity Estimates from Alternative Analytical Models

Abstract

A single-lane roundabout case study from the United States is presented to compare capacity estimates from various analytical models. Some contradictory results that can be obtained from these models are highlighted and reasons for differences are discussed. Such systematic differences have important design implications. The paper discusses why the TRL Linear Regression model may underestimate capacity for low circulating flows and overestimate capacity for high circulating flows. The case study displays an unbalanced flow pattern which contributes to significant differences between models.