The Oklahoma Department of Transportation is making progress on a project on the northeast corner of the IDL that turned out to be much more involved than it hoped.
In the summer of 2012, ODOT set out to replace the deck on the bridge that carries the off ramp from westbound I-244 to southbound I-444, which most people know as Highway 75.
The bridge was built in 1971 but had never been redecked and was in bad shape. "There were certainly a lot of patches on the surface," said Randle White, Division Engineer for ODOT.
While removing the old pavement, ODOT engineers discovered a lot of problems with the structure underneath. They forced the engineers to design a long list of repairs, and pushed back the completion date, too.
The list includes repairing or replacing the concrete and steel piers that support the bridge's huge steel girders. It also includes tearing out and replacing the end caps, which are the concrete structures that support each end of the bridge.
"The pier caps were at a state where they needed to replace those. They couldn't just patch those and go on down the road," White said.
The crews are using steel beams called falsework to shore up the girders while the work progresses. White said in some cases the falsework supports the weight of the girders, in others it actually keeps the girders from lifting into the air.
The work forced ODOT to close the entrance ramp from eastbound 2nd Street to northbound Highway 75, because it crosses under the bridge.
White said the design of the bridge makes it more difficult to fix than others. The bridge is curved and banked, a great feature for drivers that's not so great for engineers.
"Once you introduce the super elevation and the curve there that adds a degree of difficulty because as you can see the beams aren't all at the same elevation, they're kind of sloped from the high side to the low side."
Crews have actually disassembled the ends of the girders and set them aside temporarily like part of a giant erector set. Once the concrete work is finished on the support structure, the crews will reassemble the girders and the actual redecking can begin.
The redecking was originally scheduled to be complete by the end of 2012, but the extra work has pushed that back to the end of April or early May 2013.
White said the project is part of ODOT's long-range plan to refurbish all of the IDL. The north and west legs have already been rebuilt. The south leg is set to be fixed, including all of its bridges, in about a decade.