MnDOT will literally slide Larpenteur Avenue bridge into place Wednesday

With hydraulic jacks providing the oomph and "concrete shoes" with Teflon pads underneath to give it glide, MnDOT crews will push the new Larpenteur Avenue bridge over I-35E in to place during the overnight hours Wednesday into Thursday.

MnDOT will close both directions of I-35E between I-94 and Hwy. 36 from 9 p.m. Wednesday to 5 a.m. from Thursday when it uses a technique called Slide in Bridge Construction (SIBC), something that has used in a handful of other states and is being tried in Minnesota for the first time.

"It's pretty cool," said spokeswoman Bobbie Dahlke, but it's definitely not fast. It will take up to eight hours to move the 3.5 million-pound deck and beams from a temporary structure nearby where it was built onto the newly constructed new piers and abutments.

MnDOT will use hydraulic jacks that will push the deck laterally at the slow and methodical rate of 19 inches per stroke to cover the distance of 84 feet.

Motorists might experience brief closures of up to 15 minutes at time overnight Tuesday into Wednesday as MnDOT gets ready for the big move. On Wednesday, lane restrictions in the vicinity of Larpenteur Avenue will begin at 7 p.m. and a number of ramps will shut down at 8 p.m. They include ramps to and from I-35E at Maryland Avenue, Wheelock Pkwy., Roselawn Avenue and Hwy. 36. Motorists will be detoured on I-694 and I-94 to bypass the closure.

MnDOT built the deck for the new Larpenteur bridge on temporary framework to the north of the previous bridge. That allowed the agency to keep Larpenteur over I-35E open to traffic longer and minimize the length of traffic disruptions. The estimated timeframe from closure of the old bridge to opening of the new one is estimated at 35 days, compared to 60 days for bridges of similar size recently built at Arlington Avenue and Wheelock Pkwy., MnDOT said.

SIBC, also known accelerated bridge construction, is among the latest innovations states are employing at the suggestion of the Federal Highway Administration, which through its Every Day Counts program, urges states to use new technologies to shorten project delivery, enhance highway safety and mitigate environmental impacts.

SIBC, which allows bridges to be moved laterally only, is different than the methods used on the recently-built bridges at Arlington Avenue and Wheelock Pkwy. In those cases, the bridges were built off site and moved into place through a process called Self Propelled Modular Transporter (SPMT). That process uses a vehicle that jacks up the beams and deck from its staging area and moves the superstructure laterally, vertically and even in a circle if necessary. The parts can be moved hundreds of miles if surface conditions allow for it. MnDOT also used SPMT when building the new Hastings Hwy. 61 bridge. That bridge was built on land, then loaded onto a barge and floated down the Mississippi River and lifted into place.

The new Larpenteur bridge consists of two spans, each 92 feet. If you don't want to stay up all night to watch the progress, MnDOT says it hopes to capture the event on video and share it on social media sites.