A monthly update on the Twin Ports Interchange reconstruction project produced details of detours on Monday at Clyde Iron Works — and also some harrowing mental imagery of the voids the work will produce.

In some of the first work next summer, the 27th Avenue West Bridge will close, “because it will go away,” said Roberta Dwyer, “so you will not be able to cross during reconstruction.”

Dwyer, project manager with the Minnesota Department of Transportation in Duluth, echoed similar words later to describe why U.S. Highway 53 will close all the way to the Miller Hill Mall for a year beginning in the fall of 2021.

“Because those bridges are going to totally disappear,” Dwyer said, describing elevated sections of highway through Lincoln Park. “And they will all have to be put back together as one. There won’t be any place to go below Piedmont Avenue.”

With gaping holes in the infrastructure, the Twin Ports Interchange reconstruction project will bring detours. July’s update from MnDOT brought an understanding of early work and some of the associated traffic workarounds.

For instance, in some of the first work next summer, Lower Michigan Street through Lincoln Park will be closed in order to be widened by the width of about a lane. The work will be done in preparation for a year of southbound I-35 traffic being diverted onto Lower Michigan Street from fall 2020 to fall 2021.

“It needs to get widened to take on both lanes of traffic,” MnDOT design manager John Krysiak said.

Also in that stage, northbound I-35 traffic is being diverted onto the southbound lanes. Then in 2022, all I-35 traffic will use the newly rebuilt northbound I-35 while the southbound lanes are rebuilt.

Known locally as the “can of worms,” the Twin Ports Interchange is the convergence of Interstate 35 with I-535 and U.S. Highway 53 through the Lincoln Park neighborhood of Duluth. The $342 million project proposes to make the interchange safer for travelers by eliminating left-hand exits and rebuilding difficult merges. The project also offers more efficient travel for heavy freight, which is presently restricted to city streets due to weight limits on aging ramps and bridges scheduled to be rebuilt.

Planning the interchange project has been a dynamic effort, unfurling new details every month. Early on it was learned construction would run year-round from 2020 to 2022, with finishing work on I-35 being completed in spring/summer 2023.

Staring at a hanging map of detours like it were art, Krysiak listened during the public meeting to a Duluth resident talk through a detour out loud.

“So the Blatnik Bridge will stay open, but it just shoves you off 535 onto Garfield (Avenue), instead?” she said, describing a jaunt from Superior into Duluth.

“It’s why we rebuilt Garfield this year,” Krysiak said.

The Highway 53 closure through Piedmont Heights will make a detour out of Central Entrance and Mesaba Avenue. The yearlong Highway 53 closure will be expected to conclude in fall 2022. Only local traffic will be allowed on Highway 53 during the closure, Dwyer said, because MnDOT doesn't want traffic diverted onto neighborhood streets.

While detours will play a prominent role during the reconstruction project, Duluth is not an easy city to find such workarounds.

“It’s especially tough in this town, because we don’t have alternate routes,” Dwyer said. “You have basically one route coming into Duluth, I-35. In the Twin Cities, if you shut down I-94 you use 494 or 694. … We don’t have alternate routes, because with the topography of Duluth most of the city streets don’t even go through.”

Detours aren’t always the shortest routes, Dwyer said. Other factors matter, too — width of the road, the fewer residents the better, etc.

“We’re developing (detour) maps for each of the ramp closures as the project progresses for the 2020-2022 seasons,” Dwyer said.