NORTHAVEN TRAIL BRIDGE
Dallas
Award of Merit
Submitted by: HNTB Corp.
OWNER: Texas Dept. of Transportation
LEAD DESIGN FIRM: HNTB Corp.
GENERAL CONTRACTOR: Ragle Inc.
CIVIL ENGINEER: Halff Associates Inc.; EJES Inc.
The only network tied arch bridge in the world with an S-curved deck serves pedestrians crossing over the busy eight-lane U.S. 75 and its frontage roads. The bridge connects to three highly trafficked trails and provides a link to the DART station at Forest Lane.
In looking for a bridge that would become a landmark, the city had a vision for a lightweight design inspired by a bicycle wheel, with the 64 crisscrossing cables resembling the spokes and the steel arch ribs representing the rim. The bridge’s main span is a 201-ft-long network tied arch, with inclined circular arch ribs that tower 50 ft above the bridge deck. Its network cable arrangement was designed to increase the stiffness of the structure by as much as a factor of 10.
To minimize impact to the traveling public, the team built the bridge off site and moved it into place overnight using accelerated bridge construction. Crews assembled the bridge deck, cables, arch and railing on timber shoring in a parking lot east of the highway. Some elements, such as bridge columns and approaches, were simultaneously built in place.
The bridge placement took place during a single weekend. The bridge was driven on remote-controlled self-propelled modular transporters (SPMTs) and positioned roadside. SPMTs pivoted the 800,000-lb structure to span the highway. To avoid conflicts between the skewed piers and SPMTs, the team transferred the bridge to a gantry system and guided it to its final location.