The use of segmental precast girders and conventional precast/prestressed girders is helping the largest highway interchange project in North America remain ahead of schedule.

The Dallas High Five Interchange, linking U.S. Highway 75 and Interstate 635, is setting more records than its height and scope — 120 ft., $261 million and a five-year schedule — as a construction project, according to the Texas Department of Transportation. After two years (or 35 percent of the contract time), construction is 47 percent complete, notes TxDOT Northwest Area Engineer for Dallas County Larry Tegtmeyer.

Lead contractor Zachry Construction Corp., an affiliated operation of integrated Austin materials producer Capitol Aggregates, can earn an incentive for each day the project is completed in less than five years, up to a maximum of one year early. The contractor will be charged liquidated damages for each day the project completion exceeds five years. Approximately one-third of the project is constructed at night.

Approaching fall 2003, completed work includes:

• 68 percent of bridge columns (480 of 710).

• 62 percent bridge caps (255 of 409).

• 52 percent prestressed girder erection (85,000 linear ft. of 163,619).

• 63 percent segmental precast bridge girder erection (390 members set of 623).

The new interchange is expected to relieve rush hour traffic through one of the busiest interchanges in the country. About 500,000 vehicles daily travel the interchange, which has featured U.S. 75 narrowing from four lanes to two, before and after the interchange, terminating frontage roads that directed traffic onto the highway, and cloverleaf loops that slowed traffic. TxDOT expects the project to improve driver safety, better the air quality, provide easier local access, increase traffic capacity and offer flexibility to meet future growth.