Aiming to improve traffic flow and safety, the Texas Department of Transportation (TxDOT) has undertaken a bridge replacement project along about four miles of the Interstate 40 corridor in Amarillo.

“The existing structures were built with the original interstate construction,” says Sonja Gross, Public Information Officer for TxDOT’s Amarillo District. “Due to their age, traffic volumes and other factors, such as climate, the condition of these structures had degraded.”

The department had load restricted traffic on the original bridges about four years ago. Vehicles heavier than the legal weight limit of 80,000 pounds could not cross these structures.

I-40’s six lanes run east-west and carry between 45,000 and 65,000 vehicles daily in the northwestern part of the state. It serves as a freight corridor, with heavier loads than when the bridges were built.

“There has been more industrial and commercial development along the east loop and along I-40 east in recent years,” says Amarillo Area Engineer Corky Neukam. “Traffic volume has increased over the years and is expected to continue with that trend.”

The approximately $50.4 million project entails replacing six bridges, built as part of the original interstate construction, located at Whitaker Road, SL 335 (Lakeside Drive) and FM 1258 (Pullman Road). The new bridges are longer than the original structures to accommodate the addition of Texas turnarounds at the intersections, which provides a way for traffic to access the frontage road in the opposite direction.

“The turnarounds are beneficial for the stakeholders,” Neukam says. “Traffic can exit the westbound side and use the turnaround to access the eastbound side without having to go through the intersection.”

Other improvements include overlay work on the interstate’s eastbound and westbound main lanes from Nelson Street to the U.S. 287 split, reversal of the westbound ramps between Spur 468 (Airport Drive/Juett Attebury Drive) and Whitaker Road, and modifications of the remaining ramps.

“These ramps were reversed for multiple reasons,” says Neukam, explaining that the relocation of these ramps is anticipated to provide operational improvements and better access to the westbound frontage roads during the phased construction of this project.

The ramps near SL 335 needed relocation, because the profile of the I-40 mainline changed in this area.

Not only will the new bridges eliminate the weight restrictions, they also will provide increased vertical clearance of at least 17 feet. The new heights accommodate updated highway standard height requirements.

WSP USA, headquartered in New York, serves as the engineer of record and designed the plan sheet.

J. Lee Milligan of Amarillo, Texas, received the construction contract and began work in April 2018. The employee-owned company was founded in 1937, hauling dirt with one truck. Now, the company specializes in heavy highway construction in the Texas panhandle and South Plains.

“The sequence was build a detour, shift traffic to the detour, demolish the westbound bridge, excavate additional area to accommodate the longer bridge, build the bridge and complete the box under the bridge,” Neukam says. “Then we shifted the traffic back and started on the other side.”

Drilled shafts and concrete columns support the multispan bridges. The superstructure features concrete deck and bridge rails. All of that work is complete.

At Whitaker, crews are working on the eastbound deck rail, 24 feet of main lane work, the turnaround and retaining walls.

At Pullman work is progressing on a riprap embankment on both ends of the bridge, and at Lakeside, crews are building retaining walls.

The scope also included overlay work in both directions on the main lanes from Nelson street to the U.S. 287 split.

Traffic continues to flow on two lanes of the interstate during construction. Neukam explains that traffic shifted to a detour as the westbound bridges were built, then traffic was shifted to the newly completed lanes. Work then began on the eastbound lanes.

“The challenge of detouring traffic in order to build these roads and keep the traveling public moving is always a challenge,” Neukam says. “We ask our customers to be patient and understanding.”

Crews employed concrete barriers throughout the construction sequences, alerted media, posted message boards and called on law enforcement when needed.

“We hit a big milestone in mid-April 2021 when construction crews removed the temporary concrete traffic barrier on the eastbound side of I-40 between Airport Boulevard and the U.S. 287 overpass, swept the main lanes, placed the final striping, and opened all lanes for the two new Pullman bridges,” Neukam says.

“Minimizing impact to traffic, businesses and the public is always a major goal for TxDOT, and doing so on an interstate with a large volume of truck traffic is sometimes a challenge,” Neukam adds. “We planned and implemented phased construction for these bridges in a way that minimized this impact.”

The project was about 84 percent complete at the end of May and is expected to finish on time, in December 2021, with traffic returning to a normal pattern by October.

Crews worked throughout the pandemic, taking recommended precautions to keep workers safe.

Neukam says he is pleased the job remains on time, despite the pandemic during which resources are limited, including the concrete suppliers, the beam supplier, the fabricators, and local crews.

TxDOT anticipates the new bridges will serve the public for the next 50 to 75 years.

“By year’s end, we will be delivering six new bridges that meet current design standards and serve local and commerce transportation needs for several decades to come,” Neukam concludes.

Photos courtesy of the Texas Department of Transportation