The SIDRA Based Analysis on Operations of Three-Leg Modern Roundabout with Single-Lane Approaches

Abstract

Modern roundabouts are widely implemented abroad because of high capacity and well safety performance, whereas there are few studies on related theories of modern roundabouts in China. Only one three-leg modern roundabout with single-lane approaches was deployed in Suichang, Zhejiang Province of China, at present. In this paper, traffic flow were collected by laser velocimeter and digital cameras, and a simulation model was established by the SIDRA, the operations of the three-leg roundabout were analyzed, and the influences of the proportion of left-turning traffic in entering traffic volume on operations have been studied. Retrieve the critical parameters, including minimum headway, following headway and critical gap from the traffic flow data collected on-site, and select average control delay, the 95th percentile queue length and V/C as the assessment indicators. The results indicate that the 95th percentile queue length and delay will increase gently with the increase of traffic volume when the entering traffic volume is less than or equal to 600 veh/h with the proportion of left-turn traffic flow less than 20‰, or it is less than or equal to 500 veh/h with the proportion of left turn less than 20‰, and vice versa. The Level of Service of modern roundabouts can basically reach Level-III when the entering traffic volume is less than or equal to 600 veh/h.