TH 284 and Sparrow Road Roundabout, City of Waconia
The City of Waconia, in cooperation with Carver County and the Minnesota Department of Transportation (Mn/DOT) completed a corridor planning and design process to evaluate approximately three miles of Trunk Highway (TH) 284 in the City of Waconia. Expansion of the City and major modifications to the County Road (CR) 10 and other local roadways facilitated the need to improve the three primary intersections along the Trunk Highway. Bolton & Menk, Inc., on behalf of the City of Waconia, evaluated the corridor for signalized and roundabout alternatives. The City of Waconia secured Cooperative Agreement funds for the first phase of the project to design and construct a roundabout at TH 284 and 15th Street. The first phase of the project includes one of the first roundabouts on a Mn/DOT trunk highway and required the first roundabout proposal in the Mn/DOT level one layout approval process. The project was instrumental in the development of intersection review procedures at Mn/DOT for roundabouts. The project included the first Intersection Control Evaluation for a roundabout.
The first roundabout was designed with a 135’ inscribed diameter to minimize right-of-way required while accommodating the anticipated capacity, the WB-62 design vehicle, and allowing for the development of sustainable approach and exist geometry for safe and efficient operation. Bolton & Menk released the project for construction in the Spring of 2008 to meet the anticipated traffic demands with the second phase of the project, including a dual lane roundabout, was completed during the 2009-2010 construction season.