Ahead of schedule and on budget, the $230 million U.S. Highway 53 Relocation Project hit another in a series of milestones last week when the final section of bridge-spanning girders was set and fastened into place.
Made of U.S. steel, fabricated in Eau Claire, Wis., and trucked to the bottom of the Rouchleau Pit between Eveleth and Virginia, the massive girders arrived in sections that were further assembled to one another at the site. The largest ones at either end of the bridge are 14 ½ feet tall in some places.
The work unfolded in elaborate computer models before the first girder was lifted off the ground in September by one of country's largest cranes. The final girders went in Tuesday.
The girders went up in a mostly daily ballet - the crane lifting sections that weighed up to 750,000 pounds. It unfolded semi-live on the Minnesota Department of Transportation's online project camera that updates with new images every few minutes.
"It was more highly engineered than I ever imagined," MnDOT project engineer Pat Huston said. "Every girder that came in was even unloaded in a specific location."
In between completing the steel span, workers battled frigid cold and winds that were at times so strong they could blow a girder like a kite and force work on the job site to shut down or never start, Huston said.
At 200 feet over the Rouchleau Pit, the new Highway 53 bridge will be one of the tallest in the state and surpass the height of the Blatnik Bridge in Duluth.
The project includes 3.1 miles of new road to go along with the bridge. Before the weather got too cold, contractors were able to put down two layers of blacktop.
"We are currently sitting approximately two months ahead of schedule," Huston said. "We could potentially open in August, depending on the severity of the winter and how long spring lasts. It's a good place to be this time of year."
The relocation of Highway 53 was necessitated when mining interests notified MnDOT in 2010 that the road would need to be moved. While the winding four-lane highway will be drivable later this year, there will be lane closures as entrances and exits are constructed. Final landscaping will take place in summer 2018.
More than 10 million pounds of steel are now in place, awaiting warmer weather and the framing that comes before concrete pours on the bridge deck. For now, work has stopped.
Last winter workers from the contractor Kiewit, of Omaha, and more than 20 mostly local subcontractors worked six days a week, two shifts a day all winter long for dirt and rock excavation.
"We're not going to be concrete pouring in these conditions," Huston said. "It's relatively slow compared to last winter."
Now that the girders are in place, Huston can start thinking about hanging the city sewer and water pipes to the bottom of the bridge - one of the intricate details of the bridge and roadway that will include new intersections in both towns, a partially paved section of the Mesabi Trail that will carry over the bridge independent of the roadway and feature two pedestrian plazas on either end.
Huston has touted the bridge's aesthetic throughout the process and it's now coming into picture. Monthly updates near the jobsite draw between a dozen and three dozen interested townspeople and Huston said he appreciates their dedication to understanding a singular project that will help define his own career.
In the meantime, between now and the restart of construction, the steel will be left to settle in as the temperatures see fit.
"There's a lot of expansion and contraction that can happen over 1,000 feet of steel," he said, nailing the length of the bridge. "Between 40 below and 90 above, it shrinks, it grows. Every structure built outside expands and contracts. Even the piers are designed to move."