Construction crews with the Idaho Transportation Department (ITD) slid the first of two bridges into place over the weekend at the I-84 Blacks Creek Interchange. The slide-in maneuver was designed to minimize impacts on the heavily traveled area.
Crews build most of the new bridge next to the existing structure. When it is ready, the old bridge is demolished and the new one is slid into place.
“The driving force behind choosing a lateral bridge slide method was our focus on the people we serve and their ability to get where they need to go.” said Patrick Kelly, the ITD project manager overseeing the work. “We were able to keep lanes open during the entire bridge construction process. Once it was ready, we closed the eastbound lanes, demolished the old structure, pushed the new bridge into place, and are wrapping up construction on the adjacent roadway. In the end, we will have closed interstate lanes of traffic for weeks rather than months.”
To get the bridge from temporary footings to its permanent location, crews lay down Teflon pads and cover them with dish soap. Heavy machinery then pushes and pulls the bridge into place.
“Seeing how smoothly the bridge slid into place was very satisfying,” said Kelly. “It has been months of planning, preparation, and a lot of hard work to get to this point. The crews from Knife River have done a wonderful job and should be very proud of the work they've done.”
The whole process, from demolition to reopening traffic, will take two to three weeks. ITD says normal bridge replacements can take several months. With the new bridge in place, crews just have a few things to finish, including work at the bridge abutments and repaving approaches.
The second bridge for the westbound lanes has been built next to the old structure. Crews are finishing the eastbound side of the interchange, including work on the ramps and Blacks Creek Road. The second bridge will be ready to be slid into place in early August.
The Idaho Transportation Department provided this video showing the demolition and slide of the first bridge. For more information on the project, click here.