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Chelsea-Stockbridge M-52 Trail Connection

Chelsea, Michigan

Pedestrian Underpass


Washtenaw County Parks and Recreation Commission

Engineer and Landscape Architect:
Stantec - Ann Arbor


Z Contractors, Inc.


May 2020

Technical Description:

• CON/SPAN® Arch-Box Bridge System
• Span: 16’
• Rise: 11.54'
• Length: 78’

Since its inception in the late 1990s, the Border-to-Border Regional Trail System (B2B) has garnered support from Washtenaw County, and residents have rated the trail system as one of the most desired amenities in the area. B2B was spearheaded by the Washtenaw County Parks and Recreation Commission (WCPARC), the Huron Waterloo Pathways Initiative (HWPI) and other state and local government agencies. During the planning process, it became evident that the trail would have to cross M-52. Due to the road's significant traffic volume and speed, including many trucks, constructing a tunnel was a natural solution to create a safe road crossing and superior trail user experience.  

"The original design was an at-grade crossing, however, the team knew this design caused a significant safety situation," stated Mark Pascoe, Principal and Team Leader at Stantec. "HPWI was able to create a funding program to promote a tunnel concept, which was the correct approach based on the expected increased usage of the trail system.” Jeff Hardcastle, Board Chair of HWPI added, “By connecting and showcasing our communities, the HWPI hopes to encourage healthy and active lifestyles, while also promoting economic development.”

This 2.1 mile long trail segment begins at the Green Lake Compound and extends to North Territorial Road. A structure was needed at the trailhead near the intersection of North Terminal Road and M-52, adjacent to the Lyndon Township Hall, and it was decided that a 16' x 11.54' x 78' long CON/SPAN® Arch-Box Bridge System, a four-sided precast tunnel with integral precast slab foundation, would be the best solution. The precast system was selected for its ability to provide an expedited installation over a cast-in-place foundation option, as well as its ability to meet the project's strict deadline. With 4,400 vehicles per day traveling the M-52 highway between the communities, it was imperative that the road closure be limited to three weeks total, as directed by the Michigan Department of Transportation.

“Contech was instrumental in assisting the Stantec Engineering and Landscape Architect team to create an economical solution," added Pascoe, Principal and Team Leader at Stantec. "There were many iterations of design and concept considered for the final design, and the Contech team provided guidance throughout the process.”

The following enhancements were also added to the structure: stone veneer on the headwalls, a formliner finish on the 35' long precast walls, LED lighting throughout the tunnel for pedestrian safety, a colored brick paver path leading up to the tunnel and custom Korten decorative panels with an etched map of the trail system. 

The project also included the construction of 50 parking spaces, bathrooms, picnic tables and other amenities. By creating a link between the Waterloo and Pinckney State Recreation Areas, the tunnel became a defining landmark of this trail segment. Furthermore, the tunnel created a place to pause along the trail as it frames a beautiful view over Green Lake. 

Constructing a tunnel was a natural choice to cross M-52 because of the existing topography and safety provided by a grade-separated structure," concluded Peter Sanderson, Project Manager with WCPARC. "We have received a lot of compliments on the tunnel from the community who appreciates the safe crossing of the busy road and the aesthetic choices that were made." 

Technical Description:

• CON/SPAN® Arch-Box Bridge System
• Span: 16’
• Rise: 11.54'
• Length: 78’

800-338-1122 |
Project #: 590941


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