Baker Road, a major arterial within the community of Dexter, Michigan, was exhibiting signs of increased traffic congestion and accompanying concerns over the safety of motorists and pedestrians at two intersections along its route. Concerned with an uptick in delays and vehicular crashes, the City and the Washtenaw County Road Commission (WCRC) conducted a study to assess conditions and recommend solutions for the intersections of Baker Road where it meets Dan Hoey Road and where it connects with Shield Road/Dongara Drive.
At the time of the study, Dan Hoey Road was controlled by a traffic signal and carried a bulk of the large truck traffic through the City. Shield Road provided key access to Dexter High School and was controlled by a two-way stop intersection, which made it prone to long delays during peak school hours and more susceptible to crashes due to traffic back-ups. The study assessed a variety of conditions and parameters to define the best alternatives.
Ultimately, it was recommended that single-lane roundabouts be installed at both intersections. During final design, the WCRC requested that mini-roundabouts be explored. These would require less right-of-way acquisition, while still emphasizing traffic and pedestrian safety and improving flow and efficiency. In addition, the mini-roundabout design would better accommodate the turning movements of school buses and was expected to operate more efficiently in off-peak periods than compared to a signal alternatives, especially for side-street traffic.
Due to concerns about property impacts and construction costs, the design team focused on two 100-foot Inscribed Circle Diameter (ICD) designs to minimize impacts and costs while still slowing traffic and providing a safe corridor for traffic and pedestrians. The larger circle allowed for an inner circle of the central island to be slightly raised instead of making the whole central island traversable.
The result was the completion of two new mini-roundabouts along the busy thoroughfare of Baker Road, which are now providing safe, effective means of travel for residents and visitors navigating through Dexter.