Project: Five-level highway interchange
Client: Texas Department of Transportation
Location: Dallas, TX
Construction Period: 2002–2005

The Dallas High Five is a five-level interchange at the intersection of U.S. 75 (Central Expressway) and I-635 (LBJ Freeway). TxDOT expects the project will result in improved driver safety and air quality, better local access, increased traffic capacity and greater flexibility to meet future growth.

The Dallas High Five widened Central Expressway from four to eight lanes and added a high-occupancy vehicle lane that connects to LBJ Freeway. LBJ Freeway has been widened at the interchange from six to 10 lanes. Four dedicated, barrier-separated, high-occupancy vehicle lanes also have been added. The Dallas High Five has made traveling smoother for the more than 500,000 motorists who drive through the interchange each day.

The Dallas High Five was awarded to ZCC by TxDOT in 2002. ZCC officially completed the project in Dec. 2005, one year ahead of schedule. The American Public Works Association recognized the Dallas High Five with the 2006 Project of the Year award. The project was also honored with the 2006 Topping Out Project of the Year.

One-third of project work was performed at night. Pre-cast segments were used to build bridges that crossed over the center of interchanges to minimize traffic impact. ZCC developed detailed traffic control plans to allow hundreds of thousands of vehicles to pass through the construction site daily without negatively affecting the work schedule.

Zachry used a unique, balanced cantilever erector, supplied by joint venture partner Rizzani de Eccherto, to shorten the construction schedule. The 101-ton Segment Erector accommodated long span lengths and allowed for flexibility in adjusting the construction sequence. The Segment Erector was used to place individual, precast bridge segments from the ground into place while it sat atop the unfinished interchange. The first of its kind to be used in the United States, this new technology helped Zachry construct bridge segments faster and easier than traditional construction methods. The erector minimized the project's impact to traffic flow by setting segments into place above interchanges that were open for traffic.

At the time of its letting, the High Five project represented one of the largest bid-build projects ever constructed by Zachry Construction Corporation and TxDOT. It is one of the most complex transportation projects in Texas history. Rising 120 feet above the ground, the revolutionary 12-story project features:

• Five main lanes and two barrier-separated HOV lanes in each direction of I-635
• Four lanes in each direction through the U.S. 75 interchange
• A reversible HOV lane on I-635 to connect to a single HOV lane on U.S. 75
• A five-level interchange that includes main lanes of U.S. 75 on the first level, a rectangular junction of the two frontage roads on the second level, I-635 lanes on the third level and direct connection ramps that eliminate left exits on the fourth and fifth levels.

Additionally, the project included 43 bridges, covering 2.3 million sq. ft. of deck, 710 columns, 680,000 sq. yd. of concrete paving and more than 1 million cubic yards of excavation and embankment.

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