I-35W Minnesota River Bridge project could start in 2017

A replacement of the Interstate 35W bridge over the Minnesota River in the south metro may be cheaper and closer to construction than initially expected.

The project is still officially penciled in for a 2020 construction start, but the Minnesota Department of Transportation is getting the design ready so work can begin in 2017 if funding becomes available, said Jon Solberg, MnDOT’s south area manager.

That early start is by no means certain, because it hinges on passage of a comprehensive transportation funding bill in the 2016 legislative session. Still, “if a larger transportation bill did float through the Legislature, this would be a project that would be a priority for the department in the Metro District,” Solberg said.

Meanwhile, based on the latest design and engineering work, the project’s estimated cost has been revised to $110 million to $120 million, down from a previous estimate of $140 million, Solberg said.

“Basically, we have taken a harder look at everything needed for the bridge and roadway. … So that has given us a better estimate than we originally had,” Solberg said.

The project received $5.5 million in design money from the state’s Corridors of Commerce program, which benefits projects that improve the movement of freight and add capacity to the transportation system.

City officials in Burnsville and Bloomington would be happy to see construction move forward sooner rather than later. Though the project would have some major traffic impacts during construction, the work is sorely needed, said Ryan Peterson, Burnsville’s city engineer.

Peterson said the new bridge would improve safety by adding a north-bound auxiliary lane for travelers getting onto I-35W from Cliff Road, a bottleneck area that’s notorious for traffic backups and accidents during morning commutes.

“Hopefully that will be greatly reduced,” Peterson said.

Built in 1957 and widened in the 1980s, the I-35W Minnesota River Bridge is a six-lane concrete steel girder bridge that carries interstate traffic between 106th Street in Bloomington and Cliff Road in Burnsville.

On its project website, MnDOT says the project will reconstruct the bridge, replace pavement from Cliff Road to 106th Street, add an auxiliary lane and a trail between Cliff Road and 106th Street, and improve signage, lighting and drainage.

Shelly Pederson, Bloomington’s city engineer, said the bike and pedestrian trails would connect with a regional trail system in the area.

The bridge is a candidate for replacement because of its poor deck condition, age, and physical limitations, including narrow lanes and shoulders, according to MnDOT.

MnDOT says it has ruled out rehabbing the existing bridge, because it would be too expensive compared with replacement. Moreover, the existing bridge isn’t expandable. Solberg said the new bridge will be designed for a 100-year life.

Those factors “tipped the scales in favor of reconstructing the bridge,” Solberg said.

MnDOT project manager Scott Pedersen said the project is in preliminary design and is expected to be at 30 percent design by Jan. 1. Design work is on track for completion in February 2017, he said.

Construction is expected to take place over two seasons, starting with the northbound lanes and then switching to the southbound.

Pedersen said the bridge isn’t structurally deficient, but it does require extra maintenance and inspections.

Among the challenges: The project is surround by environmentally sensitive wetlands, floodplains and parkland, and a low point south of the bridge is susceptible to flooding, MnDOT noted in June 2014 request for preliminary engineering services.

Plymouth-based SRF Consulting is working with MnDOT on the design, Pedersen said.

MnDOT said it’s considering accelerated construction techniques to minimize impacts to the traveling public, as well as movable barriers, which allow for more efficient traffic management during rush hours.

The bridge is a key link in Minnesota’s interstate highway network with 109,000 average daily traffic counts, and is a “critical element” in implementing the Orange Line Bus Rapid Transit between Lakeville and Minneapolis, MnDOT said.

MnDOT will hold a pair of open houses later this month to update residents on the plans and gather public input on potential design components and bridge aesthetics.

The meetings are set for Tuesday, Oct. 27, 5-7 p.m. at Bloomington Public Works, 1700 W. 98th St. in Bloomington, and Thursday, Oct. 29, 5-7 p.m. at Burnsville City Hall, 100 Civic Center Parkway in Burnsville.