Traffic flow microsimulation for performance evaluation of roundabouts and stop-controlled intersections at highway overpass

The transportation modal share and the traffic volume demand data on a road network are essential for planning an efficient traffic management system. Traffic demand largely impacts congestion, air quality, public health, and public safety. Accurate and timely collection of traffic attributes is imperative for traffic management and performance evaluation of transportation systems. This paper presents the results of microsimulation models for evaluating traffic flow performance of stop-controlled intersections compared to the alternative roundabouts at each end of the South Lamar Blvd overpass at SR 6 highway interchange in Oxford, Mississippi. The roundabouts were constructed in 2007 and have been in operation since then. Traffic volumes and movement data were projected at 2.5% annual growth for 2016 using 2009 field data collected for the highway overpass site. The simulation results using the 2016 projected peak hour traffic data showed that converting the stop-controlled intersections to roundabouts improved traffic flow by: reducing delay by 24%, reducing idling time by 77%, and increasing average speed by 67%. The roundabouts manage the average speed of traffic traveling through the overpass better than stop-controlled intersections, therefore, reducing traffic crash risk and improving overall traffic flow. The simulation results were also used to evaluate impacts on reducing fuel wastage and emissions.