Massive girders for Illinois Tollway bridge save budget and environment

Picture courtesy of B & K Trucking.Picture courtesy of B & K Trucking.


Construction is underway on a new bridge spanning the Fox River on I-90 near Elgin, IL, and County Materials Corporation is ensuring its progress. The $95 million Fox River Bridge Project is part of the Jane Addams Memorial Tollway (I-90) Rebuilding and Widening Project, which will expand the section of tollway between O’Hare and Rockford from two to three lanes. The 1,300 ft. long bridge at Elgin is by far the largest bridge in the project, and will be the second largest bridge in the Illinois interstate highway system.

County Materials’ Janesville, Wis. facility is manufacturing 144 prestressed concrete I-beam girders for the project. To accommodate the width of the Fox River valley, the girders are truly massive, spanning up to 168’-6” long and measuring 90” in height. The 186’ wide bridge will be eight girder spans long, at 18 girders per span, for a total of 23,388 linear feet of high performance concrete I-beam. The extra-large girders reduce the number of piers needed, an economical design feature that also helps minimize environmental impact on the waterway. Once complete, this bridge is expected to last 35-70 years with minimal maintenance, saving significant funds over time compared to a bridge built with steel girders.

The Fox River Bridge beams are the largest that County Materials’ Janesville plant has produced to date. Manufacturing girders of this size requires exceptional care. Up to fifty .6”  strands, including twenty two draped strands per girder are subjected to 44,000 lbs. of force before being encased in 8,000 psi concrete in order to achieve a unit that will hold up to the stress of bearing the weight of approximately 100,000 vehicles per day . To accommodate the unusually high tension, the manufacturing crew used special high strength rods and restraining devices, and a special holdup frames.

Another unusual feature of the girders is the lift device.  Extra prestressing strands are normally used to create lift groups on the ends of girders, which are lifted into place by a crane. For the Fox River Bridge, a special gantry system is being used in lieu of a crane to keep traffic disruption to a minimum. The beams will be moved sideways into place via an overhead trolley. To accommodate the special equipment, each girder contains a series of 6 holes in the web at each end, into which identical assemblies, each including six high strength bolts will be used to lift the girders both at the fabrication plant and at the job site. “We have to make sure when we pour that everything lines up perfectly,” says County Materials’ operations manager Ziad Sakkal.

Delivery of the immense girders also requires finesse. The heaviest beams weigh an estimated 194,000 lbs. and require special steerable trailers to transport.

The beams will be transported at a maximum of 45 MPH during daylight hours only, accompanied by two escort vehicles. A police escort may also be employed. “It’s a matter of getting them to the jobsite safely; it’s as important as making them,” explains County Materials sales representative Andy Keenan.

The bridge is being built in stages to minimize traffic disruption. Currently 24 girders are under construction for the first, bridge-widening phase of the project. These will be delivered before the end of 2014. An additional 72 beams are scheduled for delivery in 2015, and the remaining 48 will help complete the bridge in 2016.

 Editor’s note: This article was written by County Materials Corp. Pictures are courtesy of B & K Trucking.