CONVERTING OLD TRAFFIC CIRCLES TO MODERN ROUNDABOUTS: MICHIGAN STATE UNIVERSITY CASE STUDY

Modern roundabouts have become an increasingly popular form of intersection control in the United States over the past decade. With hundreds of traffic circles existing in the United States that do not meet the e\definition of a modern roundabout, a low cost improvement approach should be developed to modify such traffic circles to appropriate roundabout standards. The campus of Michigan State University contains three such traffic circles, all of which perform at an acceptable level of service. At one of these traffic circles, safety has become an issue due to the increasing vehicular, bicycle and pedestrian volumes on campus. Minor changes are proposed as cost-effective means of providing greater vehicular, bicycle and pedestrian safety while enhancing capacity. Traffic and pedestrian counts and vehicle speed studies were conducted and used in conjunction with six years of crash records to determine necessary improvements. Since no established roundabout guide currently exists in the United States, British roundabout standards were used to evaluate and design the improvements to the traffic circle. The primary purpose of this study is to provide methods by which to transform a traffic circle into a facility that more closely meets the definition of a modern roundabout. The ultimate intent is this study, upon implementation of the proposed countermeasures and review of after crash data, is to provide a model for other campuses or municipalities in North America facing similar safety issues with traffic circles.