Six months after construction began at Stewart Tunnel, the long-closed landmark on the Badger State Trail has undergone its most visible transformation in years. Crews have installed a new metal liner through nearly the entire tunnel, rebuilt drainage beneath it and filled the space around the liner with thousands of cubic yards of cellular concrete as the project moves toward its final stages.

M-Z Construction Inc. of Livingston, the general contractor, began work at the site in early April. Project Manager Lucas Zimmerman said the company expects to remain on the job until roughly mid-November, but much of the difficult work inside the tunnel is already complete and their remaining work is largely focused on grading and trail restoration outside the portals.

The Wisconsin Department of Natural Resources closed Stewart Tunnel in 2019 after loose limestone fell from the ceiling and side walls, creating a safety hazard for trail users. The state eventually selected a corrugated metal liner as the long-term repair after studying several alternatives and taking public comment.

The repair is much more extensive than simply covering the old rock walls. State plans called for about 1,150 feet of flanged corrugated metal liner, footings, backfill, drainage, bulkheads and restoration of the trail through the tunnel, along with approximately 8,100 feet of additional trail work outside it.