Inside the Tollway
It’s not easy demolishing a 4,900-foot-long, four-lane, concrete-and-steel bridge that stands 40 feet high and is supported by 53 concrete piers.
But crews working through the winter using cranes and concrete saws already have removed about 35 percent of the northbound Mile Long Bridge on the Tri-State Tollway (I-294), which closed last November when a new, adjacent bridge opened.
Weather permitting, they expect to finish demolishing the massive structure by October, although construction of a new southbound bridge on the same site will start even before the old bridge is completely gone.
The work is part of the Tollway’s $4 billion Central Tri-State Tollway Program, which is rebuilding and widening 22 miles of I-294 between Balmoral Avenue in Rosemont and 95th Street in Oak Lawn.
“This is a complex project so we’re pleased this work is proceeding on schedule, despite the weather challenges we’ve faced at times this winter,” said Illinois Tollway Executive Director José Alvarez. “Removing this portion of the Mile Long Bridge is critical because it allows us to proceed with the construction of the new southbound bridge needed to complete this project and provide a safer, state-of-the-art bridge for our customers.’
Opened in 1958, the Mile Long Bridge is being replaced with two side-by-side, five-lane bridges that are projected to operate for up to 100 years.
The new northbound bridge opened last fall just east of the original northbound span, which was then closed to traffic.
That closed bridge now is being demolished to make room for the new southbound bridge.
Crews are using concrete saws to cut the parapet wall along the bridge and remove the bridge deck in slabs. The concrete sections are removed from the bridge and further processed for re-use by further breaking down the concrete and removing the steel rebar inside.
As part of the Tollway’s commitment to sustainability, the concrete is being crushed and processed onsite. The material will be used in the project as base for roadway or ramp approaches to the new southbound bridge, or for access roads.
After each portion of the bridge deck is removed, the supporting concrete beams are also removed and later broken up onsite so the concrete can be reused in the bridge project.
When all the decking and beams have been removed, the 53 towering concrete piers that supported the bridge will demolished and removed, although their underground foundations will be left in place.
So far, the walls and decking on nearly 20 of the 54 bridge spans have been removed, although work was stopped because of storms and cold weather for several weeks in late January and early February.
Later this year, even before the demolition work is completed, crews will be begin drilling and sinking caissons for the piers needed to support the new southbound Mile Long Bridge. It will run adjacent to the new northbound bridge, roughly following the route of the demolished span.
The new southbound bridge is scheduled to open by the end of 2022, with the entire Mile Long Bridge project wrapping up in 2023.