Minnesota Will Begin I-35 Tunnel Concrete Work

The Minnesota Department of Transportation will initiate concrete grinding inside the I-35 tunnels starting September 28.

Updated on Sept. 23, 2026 in Construction

Isometric editorial illustration of a concrete milling machine head next to a tunnel wall section, representing infrastructure maintenance. — The Minnesota Department of Transportation will begin concrete grinding operations in Duluth's I-35 tunnels on September 28, 2026, requiring traffic adjustments. AI Illustration. Upload story photo >

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Concrete grinding operations in Duluth's I-35 tunnels are scheduled to begin on Monday, September 28, 2026. This infrastructure maintenance will continue through early October.

Why it matters

The project is essential for ongoing tunnel maintenance and safety, though it will necessitate traffic pattern adjustments for commuters.

The Minnesota Department of Transportation will manage the project over an 11-day timeline. The scope includes a full day closure of the Lake Avenue northbound on-ramps and southbound off-ramp.

The players

Minnesota Department of Transportation

This state agency oversees the planning, construction, and maintenance of Minnesota's complex transportation infrastructure systems.

The details

Drivers will experience single lane traffic during construction hours as crews perform grinding work inside the tunnels. Additionally, the northbound on-ramps and southbound off-ramp at Lake Avenue will face a full day of closure in mid-week.

September 28, 2026: Concrete grinding work begins in I-35 tunnels.
Mid-week of the week of September 28: Lake Avenue ramp closures will occur.
October 8, 2026: The construction project reaches completion.

Market Landscape

The project follows the Minnesota Department of Transportation 2026 Highway Infrastructure Plan to maintain critical transport arteries. It reflects a wider industry effort to prioritize the longevity of aging tunnel structures over more costly total replacements.

Commuters should expect delays and plan for alternate routes due to the single lane traffic and specific ramp closures at Lake Avenue. Residents are advised to monitor official traffic alerts to navigate the area efficiently during the construction window.

The takeaway

Travelers should budget extra time for their daily commutes while these maintenance crews work inside the I-35 tunnels. Preparing for the mid-week ramp closures at Lake Avenue will help minimize disruptions for those moving through downtown Duluth.