The voids under northbound Interstate 75 in Madison Heights required temporary closures while repairs were made.

The voids under northbound Interstate 75 in Madison Heights required temporary closures while repairs were made.

Photo by Deb Jacques

MDOT shares insight into I-75 sinkhole repairs

By: Andy Kozlowski | Madison - Park News | Published August 5, 2021


MADISON HEIGHTS — The first week of August saw a stretch of northbound Interstate 75 temporarily closed while the Michigan Department of Transportation, or MDOT, worked to address a sinkhole that was forming as a result of construction under the freeway.

At press time Aug. 3, a single lane on northbound I-75 had been reopened, and officials with MDOT said the situation was safe and under control.

Rob Morosi, spokesperson for MDOT, explained the circumstances behind the voids that had formed under I-75 between I-696 and 12 Mile Road.

He said the voids were discovered July 30, resulting in the closure of the northbound I-75 service drive from Lincoln to Gardenia avenues. The voids were discovered under the northbound service drive near 11 1/2 Mile Road — a section of northbound I-75 that will be rebuilt in 2022 as part of the I-75 modernization project.

That project had already resulted in both directions of I-75 being reduced to two lanes between Eight Mile and 13 Mile roads while crews continued with road and bridge building. The section north of I-696 has been reduced to two lanes for work on the southbound I-75 bridge over 13 Mile Road, and for replacement of the 11 Mile Road overpass above the freeway.

Part of the modernization project involves the construction of a 4-mile-long drainage tunnel, which is being built under the northbound service drive from Eight Mile to 12 Mile roads, the section of the project where the majority of the freeway sits below street level.

“During mining operations (to install the tunnel), the boring machine hit a pocket of sand and silt that contained underground water,” Morosi said in an email. “This led to the tunnel beginning to take in water and the sub-base of the road began to lose stability, dropping about a foot along the service drive and an inch or so along the northbound lanes of the freeway. Think of an hourglass with the bottom portion being the tunnel.”

The service drive and northbound lanes were closed so that the foundation of the road could be stabilized. By Aug. 1, there was no more movement or sinking of the pavement along the northbound lanes of the freeway. As of press time Aug. 3, repairs had just begun in earnest, and a single lane had been reopened along the shoulder, with plans to reopen the left lane if no more instability is detected. The center and right lanes — which received the most impact — needed repair, and Morosi said he had no estimates on how long that will take.

“Every effort will be made to have it completed as soon as possible,” he said.

Morosi explained that the drainage system itself will be a valuable asset for the freeway when it is fully installed.

“Upon completion, the drainage tunnel will capture all stormwater from the freeway and service drive, with the ability to store the water during major rain events and then discharge at a reduced rate in the county drain located at 12 Mile Road, in an effort to not overwhelm the system,” Morosi said. “Think back to the Aug. 11, 2014 storm when the freeway flooded, especially in the area of I-696.”

Roslyn Grafstein, the mayor of Madison Heights, said in an email that she has faith the overall project will be worth any short-term trouble.

“While like everyone else, I am frustrated with the increase in traffic on our freeway and city streets, I understand that construction takes time and is necessary to complete the roads so that we can reduce congestion and commute times in the future,” Grafstein said. “When finished, the updates will improve our commerce by reducing driving time, and provide better ease of access to our Madison Heights businesses and to our residents that travel outside the city.”