It's been nearly a half century since the Texas Dept. of Transportation has taken on a project this ambitious. The $1.9-billion widening and upgrading of 96 miles of Interstate 35 in Central Texas from Salado to Hillsboro make up the most miles of new construction the agency has tackled simultaneously since it first built the state's highway system.

As a key north-south transportation and economic corridor in the center of state that stretches a total of 492 miles, I-35 is known as "Main Street Texas." Given the upgrade program's massive scope, the main challenge has been synchronizing 17 construction contracts in the 96-mile upgrade zone while minimizing disruptions for the 60,000 to 100,000 daily vehicles that travel there. Currently, eight projects covering 60 to 65 miles and totaling $938.4 million are under construction.

TxDOT contracted the Texas Transportation Institute in Austin to assist with mobility coordination and traveler information during construction. Other agency districts are providing engineering and construction management support.

"Each contract that was bid had incentives for early completion," says Andy Petter, deputy district engineer for TxDOT's Waco District, the project owner. "We also included incentives for windowed milestones, which limit days of closure for certain phases." The project includes widening I-35 to six lanes with four frontage roads—six through the city of Temple. It is funded by a mixture of federal money and funds from Texas Proposition 12 and Proposition 14.

TxDOT began planning in 1999 to determine how to prioritize and break up the project areas and coordinate maintenance in the interim, Petter says. "We used a lot of consultants because we didn't have the manpower to do all the advanced planning work and project development in-house."

Individual phases present their own considerable challenges. A $205-million contract, scheduled to be let in September, is arguably the most complex portion of the project. Section 2B is a 5.85-mile section that "goes right through the heart of Temple, in an urban, population-dense area," Petter says. "It will require dealing with the railroads, two overpasses and one underpass, a lot of retaining walls and drainage challenges, replacing interchanges and working with local citizens, school districts and emergency folks."

Sequence of Events

Six contracts totaling $414.5 million have already been completed, with only two more left for award following the one in September. One $17-million contract is set to be bid in July 2013, and a 7.9-mile section in Waco set to cost $280 million is not yet funded. All are expected to be completed by mid-2017, except for the Waco project.

James Construction Group, Baton Rouge, La., has the lion's share of contracts currently under construction with four projects, totaling $421.5 million. The firm began work on the first eight-mile project known as Section 1C in December 2010, but the other three recently began in March, June and July. Within the scope of the four projects, James will excavate 3.19 million cu yd, build 26 bridges, build and install 50,015 linear ft of concrete box culverts, install 121,381 linear ft of reinforced concrete pipe and lay down hundreds of thousands of sq yd of concrete and retaining wall.

The contractor is challenged with coordinating personnel and equipment at the four contract locations, says Danny Hester, president of James Construction. With a local office in Belton, James has the benefit of familiarity with the local work force, subs and suppliers.