on the west side of US 75 and the Cottonwood Creek and White Rock Creek trails on the east side. The Texas Department of Transportation (TxDOT), the bridge’s owner, called the bridge “a regional example of the positive benefits of appropriate location and design aesthetics for future bicycle and pedestrian trails and amenities.” Why was the Northaven Trail Bridge project important to TxDOT? The Northaven, Cottonwood Creek and White Rock Creek trails are heavily used and end on either side of US 75. To cross and access the trails on the other side of the highway—one of the busiest roadways in Texas—cyclists and pedestrians previously had to use a connection under the highway main lanes that did not have updated drainage or lighting. TxDOT wanted to remedy this by establishing an easily accessible trail connection across the highway. What were TxDOT’s project goals? What challenges was the project designed to address? Beyond creating a safe connection across US 75, a key project goal was to deliver the Northaven Trail Bridge with minimal impact to the traveling public. TxDOT required that either a frontage road or a lane both northbound and southbound on US 75 remain open throughout construction and that any main lane closure period be limited to Saturday overnight. This allowed for roughly 250,000 vehicles to continue daily without disruption. What was HNTB’s involvement in the project? Working with TxDOT, HNTB served as conceptual designer, engineer of record and construction phase services provider on the project. The firm also participated in public outreach to stakeholders, including trail users, communities, and organizations located near the trails, to gather input on the community’s needs and wants. What design considerations were key to developing plans for this bridge? How is this bridge an example of industry innovation? HNTB designed a structure that was a lightweight, redundant system that could be safely transported to its final location on self-propelled modular transporters (SPMTs). This accommodated accelerated bridge construction, which allowed the bridge to be built off-site and moved into its final location overnight. In addition, Lee Kleinman, the former Dallas City Council member who originally proposed the idea for a bridge over the highway in the early 2000s, was inspired by the idea of representing a bicycle wheel in the bridge’s design. The original network tied arch concept for the main span was developed in 2017 by HNTB to reflect all stakeholder feedback. The network cable arrangement greatly reduces bending in the arch and deck and, in this case, has the added benefit of being reminiscent of the spokes on a bike’s wheel, as Kleinman envisioned.
The final design adhered closely to some of the early sketches and modeling concepts developed from conversations with the City of Dallas and other stakeholders. “Often, an early concept design and what is ultimately built are quite different,” said Tom Kramer, HNTB project manager during the plans, specifications and estimates portion of the project. “In this case, we developed a unique initial concept and saw it all the way through to completion.”
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Spring 2024 csengineermag.com
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