A Comparative Analysis of Roundabouts and Traffic Signals through a Corridor

This thesis presents a case study on an urban arterial corridor consisting of four intersections located in Baton Rouge, Louisiana. The research evaluates alternative roundabout designs in order to improve traffic flow through a currently congested corridor. The objectives of the research were to evaluate the effect of roundabouts in an urban arterial corridor, select the best alternative for the given corridor characteristics, and test the capacity of the alternative roundabout corridors. The three alternatives that were considered as part of this study were the existing signalized corridor, a partial two-lane roundabout corridor, and a partial three-lane roundabout corridor. Field data was used to model the alternatives in VISSIM, a micro-simulation software. Statistical analysis software, SAS Enterprise Guide 6.1, was used to analyze the results and determine if there were significant differences between the results for each alternative and each intersection. The performance measures used to compare the alternatives were average vehicle travel time, average delay per vehicle for each corridor, and average delay per vehicle at each intersection. The results showed that the overall alternative roundabout corridors provided a benefit over the existing signalized corridor for the existing traffic volumes tested. The partial three-lane roundabout provided the lowest vehicle travel times and lowest average delay due to the added capacity. For the higher traffic volumes at the interchange, the partial two-lane roundabout had a higher average vehicle travel time exiting the exit ramp than the existing corridor. The statistical analysis of the average vehicle delay at each intersection indicated that there were no significant differences between the alternatives at a five percent level of significance at the interchange. These results revealed potential operational issues roundabouts encounter at an interchange intersections