M-89 Corridor Improvements and Roundabout, Allegan, Michigan
CLIENT: Michigan Department of Transportation, in partnership with the City of Allegan
In southwest Michigan, a key corridor serving regional traffic, tourism, and agriculture has been modernized to improve safety and efficiency. The reconstruction of the M-89/M-40/Hubbard Street intersection into a five-leg roundabout, combined with pavement improvements along M-89, has earned national recognition from the American Association of State Highway and Transportation Officials for its contribution to quality of life and community development.
Led by MDOT in partnership with the City of Allegan, the $7 million project addressed a complex, high-conflict intersection where multiple state routes converge. The solution replaces traditional traffic control with a roundabout that reduces conflict points, lowers vehicle speeds, and improves overall traffic operations.
Clark Dietz supported the project as a subconsultant to C2AE, providing roadway and traffic engineering services critical to the intersection’s design and performance. Work included roundabout geometrics design and Rodel analysis to guide operational efficiency, along with intermediate roadway design, signal design, signal operations, and safety studies.
The 1.89-mile project extended beyond the intersection to include a concrete pavement inlay along M-89 between M-222 and 29th Street. These improvements enhance ride quality and extend the lifespan of the corridor while maintaining traffic flow during construction.
Design considerations accounted for a wide range of users, including passenger vehicles, commercial trucks, and large agricultural equipment. The project also incorporated pedestrian improvements, including a new sidewalk connection to strengthen accessibility and support safer travel for nonmotorized users.
Recognized by AASHTO with a regional award in the Quality of Life and Community Development category, the project reflects a balanced approach to infrastructure. It improves safety and mobility while supporting the needs of the surrounding community.
This effort highlights effective collaboration between MDOT, the City of Allegan, C2AE, and project partners, with Clark Dietz providing targeted engineering support to help deliver a safer, more connected corridor.
