MDOT weighs 2 options to fix Rouge River I-75 bridge

Tom Greenwood
The Detroit News

After years of complaints from drivers with chattered teeth and damaged cars, the Michigan Department of Transportation is scheduling extensive repairs to the battered Interstate 75 bridge over the Rouge River in southwest Detroit.

MDOT said Tuesday it’s considering two plans to replace the decking of the 8,627-foot-long bridge, which carries an average of 100,500 vehicles per day within sight of gasoline storage facilities and the massive Ford Rouge Plant. Work is expected to begin in the winter of 2017 and last two years.

Matthew J. Chynoweth, deputy Metro region engineer for MDOT, said it’s crucial that the decking be upgraded on the 48-year-old bridge, which carries 37 million vehicles a year. About 15 percent are trucks, he said.

“Where would those 37 million vehicles go if this bridge wasn’t here?” Chynoweth said at a news conference.

According to MDOT, the bridge piers — some of which are 100 feet tall — are considered to be in good condition because of regularly scheduled maintenance. But the span’s decking is rated as being in poor condition. Drivers have reported falling concrete and gaping potholes. In some spots, the damage has bored completely through the deck.

Chynoweth said the state has invested $65 million in repair and upkeep for the Rouge River Bridge since it opened in 1967. The span’s last routine inspection was seven months ago; a detailed substructure inspection was conducted last winter, he said.

“The piers are in fair condition, but it comes at a price,” Chynoweth said. “We’ve been patching and repairing it as we go.”

All concrete elements on the bridge contain slag aggregate, which is less durable. It also has large areas of concrete breakup, random cracking and large spalling — where reinforcing bars corrode and split the concrete — with exposed steel reinforcement.

MDOT’s preferred plan, costing $80 million, is to replace the deck using conventional materials — reinforced concrete with epoxy-coated rebar.

Traffic would be handled either through the use of lane restrictions, crossovers or detours.

That plan, along with scheduled maintenance of the piers and substructure, is expected to extend the span’s life by 50 to 60 years.

The second option: Replace the deck with precast concrete reinforced with epoxy-coated rebar at a cost of about $119 million.

During the project, three lanes of traffic would be maintained in each direction, with workers replacing 50 to 100 sections of the deck at night when traffic is detoured.

Chynoweth said the second option likely would take up to four years to complete, and “we’re not comfortable with that.”

MDOT has not used precast deck panels on existing bridges before.

MDOT also has looked at the possibility of replacing the entire bridge, with initial construction costs estimated between $271 million and $315 million. The cost of demolishing and replacing the bridge could grow because of environmental issues, including impacts to the community and to area railroads.

Requirements from the U.S. Coast Guard about the length and height of a new span also could increase the cost of replacement.

MDOT officials are concerned that funding for an entirely new bridge would not be obtained within the remaining service life of the current bridge deck.

“We believe we can keep the piers in good condition for the additional 50 to 60 years the new deck would provide to us,” Chynoweth said. “Then we would consider replacing the entire bridge.”

The bridge’s condition has long vexed motorists traveling through Detroit or commuting to the city.

In November, MDOT closed one lane in each direction for two weeks for repairs following two yawning potholes near Schaefer.