by MaryAnne Block
At long last, the public will now begin to see progress on the Hwy. 75 bridge over the Sauk River between St. Joseph and Waite Park.
The six-month project began in late December 2023. First the concrete and all the re-bar had to be removed. Both the concrete and re-bar were then recycled. It was a major undertaking to dismantle and remove the below “deck” (driving surface) of steel upright supports and beams, which proved to be a cold, lengthy process. The steel was then recycled.
Stearns County Assistant Engineer Mike Decker was on hand to explain the history and the process involved in this major undertaking.
“This is the largest bridge project we have in the county this year,” Decker said. “We do have larger box culvert projects, but for this project, bids were taken.”
Decker noted the deck (driving surface) of the bridge looked pretty good, but from underneath it was a different story. Some of the steel supports were rusting and pieces of concrete were falling. The bridge, built in 1953, has served the area well for 71 years.
“We knew something had to be done now to prevent a collapse,” Decker said.
From late December through March 14 the below deck and in-the-river work was done. Huge concrete abutments (piers, cross-ways supports) were poured and then time took over until they were completely cured (their concrete dried solidly). The Minnesota Department of Natural Resources required the river part of construction to be done by March 14 so that fish spawning would not be interrupted.
On March 15, the first above-ground work began. That very day a massive crane was brought in and the first eight of 24 concrete beams were put in place, starting on the west end.
Beams, placed lengthwise to support the deck, are each 92 feet long and weigh 70,000 pounds (35 tons). The beams are made in Elk River and delivered one at a time by semi. Four beams arrive in the morning, four in the afternoon. This process was repeated March 18 and 19.
The huge crane lifts each 92-foot-long beam off of the semi and slowly swings it over to the abutments (concrete cross-ways supports). One bridge crewman holds a rope attached to the end of the beam to help stabilize and prevent it from spinning in the wind. As it reaches the abutment, other members of the crew help guide the crane placement so the beams perfectly line up with the massive re-bar used to strengthen and stabilize and align the beams.
To get a perspective, with each beam at 92 feet long, each is nearly the third of the length of a football field. So the future driving deck over the river will be about as long as an entire football field, plus the length of the approaches to actually reach the bridge itself.
Eight beams, from right to left, create the width of the bridge. Three series of eight are placed lengthwise, in the direction of the highway.
Lunda Bridge Builders of Wisconsin won the project bid. The $4.7 million bridge will be paid for primarily by federal funding, with some state and county money as well.
“Construction,” Decker said, “is on schedule with projected completion date at the end of June this year.”
Stearns County Assistant Engineer Mike Decker was on-site at the Hwy. 75 bridge to update the public on the progress. He is standing by a smaller crane than the special crane brought in to handle oversized concrete beams.
An oversized crane lifts a 92-foot, 35-ton concrete beam off the semi that delivered the support beam. Twenty-four beams, eight across, are the start of the above-ground preparation for the bridge that will carry traffic.
