The Interstate 35E/Interstate 30 interchanges, better known as Dallas’ Mixmaster, formed one of Texas’ top 20 congested roadways and one of the country’s worst bottlenecks. As preliminary design engineer, HNTB helped the Texas Department of Transportation reconstruct the facility into a streamlined U-shape, replace multiple bridges and add flyovers, interchanges and frontage roads.

HNTB led technical efforts for successful contract execution in what was the shortest procurement schedule ever completed on a TxDOT design-build project. The firm performed 30-percent design, preliminary construction phasing and secured Section 408 construction clearance from the U.S. Army Corps of Engineers. In addition, HNTB led the preparation of an environmental assessment and finding of no significant impact for improvements, developed aesthetic design guidelines that helped garner stakeholders support throughout the decision-making process and helped obtain NEPA environmental clearance in 10 months.

With the momentum it needed to meet an accelerated schedule, the Horseshoe Project moved into design-build on time with limited changes to HNTB’s design guidelines.

In addition to the EA/FONSI, HNTB developed aesthetic design guidelines, which were instrumental in garnering support from a variety of stakeholders during the transportation decision-making process.

  • Corps of Engineers grants Section 408 clearance
  • Environmental approval secured in 10 months
  • Universal support generated for aesthetic guidelines

Location: Dallas, TX

Client: Texas Department of Transportation