“On this project a lot of the new overpass structures are being built with those prefabricated components to help accelerate construction and reduce the impact on traffic,” Barton says.

What’s working in Waco

In the current round of projects, TxDOT's Waco District is the hub of activity. James Construction Group of Belton, Texas, is expanding eight miles of road from Salado to Belton, a $106.7-million project. The company also is working on a $123-million, 6.4-mile section north of Temple and a $90-million, 3.4-mile section through Salado.

Houston-based contractor Webber is working on three I-35 contracts: a $36.8-million, 5.5-mile section north of Abbott, won in July 2010; a $100.9-million award won in February to build an 8-mile section from West to Abbott; and an $88.4-million, 3.4-mile section south of Waco that is using precast concrete beams.

Williams Brothers Construction Co. of Houston is adding lanes to a 13.4-mile section north of Waco as part of a $166.8-million contract.

Coming up, TxDOT is set to award a 9.8-mile section and a 9.6-mile section this fall. Two projects, one 5.9 miles long and another that is 7.9 miles in length, remain unfunded in the district. A new I-35 bridge spanning the Brazos River will use an “extradosed” design, not used before in Texas but common in Europe.

“The city of Waco wanted something different than the normal slab-and-deck bridges we install,” says Greg Malatek, Waco District department director, noting that the unique bridge is similar in cost to the district's typical bridges.

The two 620-ft-long, three-lane bridges, designed by AECOM's San Antonio office, will include steel beams working in conjunction with pylons anchored by shallow-angled cables that will carry between 20% and 30% of the bridge load. “The cables create a compression force that helps support the deck,” says Alanna Bettis, TxDOT design and project development engineer. “You are balancing the loading between the supporting superstructure—which would be the beams and the girders—and the shallow anchored cables that are supporting the deck portion.”

Drill shafts that are 10 ft in diameter and about 50 ft deep will serve as a foundation for the bridge. The shafts will transition into aesthetic columns and pylons. The beams rest on a continuously poured concrete cap that helps support the deck. The Art Deco-style bridges include sidewalks and overlooks for pedestrians.

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