To improve safety and boost economic impact, the Texas Department of Transportation (TxDOT) undertook an upgrade to turn State Loop 335 around the City of Amarillo, Texas, into a four-lane, controlled-access freeway.

However, with total estimated construction costs topping $1.5 billion, the 43.5-mile, multi-phased upgrade will take a while. So far, two projects finished and three more are under construction. In the current work, TxDOT and their contractor, Allen Butler Construction, Inc., of Amarillo, Texas, faced unusual challenges – relocating prairie dogs from the field in front of the historic Amarillo Helium Plant, out-of-season flooding, and, of course, a global pandemic.

Each phase of the SL 335 project lets separately for a low-bid contract. With funding from the Amarillo Metropolitan Planning Organization and the Texas Transportation Commission, three more phases will start construction in the next few years. The rest await over $1 billion more in funding.

When finished, the new freeway will feature two lanes in each direction, with accommodation for two additional lanes in the center. The work also includes ramps, one-way frontage roads with bicycle and pedestrian paths, and three-level interchanges at Interstate 40 East and West, Interstate 27, and U.S. 87. The upgraded SL 335 will support the Ports-to-Plains Corridor, which aims to expedite transportation of freight and goods along a route from Mexico to Canada.

TxDOT developed a master plan for the entire loop, dividing it into four main segments (labeled A through D) corresponding to the geographic quadrants. In general, construction proceeds clockwise.

“The SL 335 expansion started on the south loop, just east of I-27,” said Corky Neukam, P.E., Area Engineer for TxDOT’s Amarillo District. “The next expansion projects included the entire southwest quadrant (Segments B-1 and B-2). The next funded project is Segment C-1, which begins the expansion for the northwest quadrant.”

The upgraded loop will generally follow the existing alignment, except for part of segment B. That section, referred to as B-2, will be constructed on a new alignment to re-route the loop around a portion of existing roadway that evolved into an urban arterial.

In order to move the B-2 segment a mile to the west, crews will build an overpass above I-40 and Amarillo Boulevard. That bridge will cross over the footprint of the abandoned Amarillo Helium Plant.

When the historic plant opened in 1929, it was the world’s only helium production facility. During World War II, the plant served national defense needs. After 1943, it became the chief helium research and development facility in the U.S. The plant closed in 1996 and has been determined eligible for the National Register of Historic Places.

Because of its history, “As part of TxDOT’s Memorandum of Agreement [for right-of-way acquisition for the overpass], we worked with a variety of stakeholders to preserve the story of the helium plant, conducting public involvement and educational campaigns,” said Sonja Gross, Public Information Officer for TxDOT’s Amarillo District.

Before construction of the new location roadway could begin, TxDOT needed to relocate a colony of prairie dogs. They hired Lynda Watson, a professional prairie dog relocator, to capture the animals and help move them to a ranch 100 miles away.

“Ranchers have become increasingly aware of the benefits offered by the presence of the prairie dog,” Watson said. “They get to the mesquite as it comes up and clip it off before it becomes overgrown brush.”

Watson invented a technique to safely and humanely capture the prairie dogs by introducing soap suds into the holes of their burrows. That encouraged the prairie dogs out of the holes so they could be placed in traps, then quarantined for two weeks before settling at the ranch.

In the first phase of the B-2 project near the Helium Plant, crews built frontage roads, including northbound and southbound bridges over a playa lake.

“When the playa lake is full of water, it restricts our construction, so there was specific seasonal timing to get that done,” Neukam said. Unfortunately, “There was still a time when it flooded. We had to pump all the water out so we could continue construction, and we built some dirt levies to keep water out.”

In addition, the Canyon Independent School District is building a new high school in that area. “We’ve been maintaining a service road so they can get their construction vehicles in and out,” Neukam said.

In a nearby project (labeled B-1, phase 1), “We replaced both the northbound and southbound bridges on I-27 over SL 335, so we had to detour traffic to one side of the road while we built the other side of the road,” Neukam said. “We’re also tying in the new frontage roads and new mainlanes on the loop under I-27. Through all that, we need to give our stakeholders access. Tying their driveways in and reducing the congestion in front of their businesses is always a challenge.”

For the new decks on that project’s SL 335 mainlane overpasses at Coulter Road, TxDOT chose internal cure concrete for the first time in the state. “It cures from the inside out,” Neukam explained. “It’ll provide higher durability and longevity. We’ll pour that deck early in first quarter 2021.”

Throughout construction this year, as with many projects, “The biggest impact has been COVID-19,” Neukam said. “We’ve had to strategically utilize resources as efficiently as possible to address multiple phases of the overall project.”

For instance, “The crew tying steel for one of our bridges got quarantined and couldn’t leave their home base,” he said. “That put our project on standby until that crew was released to travel again. We’ve also had a couple crews quarantined locally because of exposure to COVID. Sometimes we run a skeleton crew and sometimes we put together crews with different skillsets to push forward.”

Despite the challenges, work remains on schedule. The next project – B-1, phase 2 – will start construction this spring.

Segment A (southeast loop)

• A-1 – $39.9 million; 3 miles of mainlanes, frontage roads, and grade separations at arterials; completed in summer 2019 by J. Lee Milligan, Inc., Amarillo
• A-2 – $17.4 million; 0.8 miles of mainlanes, frontage roads, and a railroad bridge; completed in spring 2018 by Webber LLC, Houston
• A-3 – $340 million; 9.6 miles of mainlanes, frontage roads, and grade separations at arterials; awaiting funding
• A-4 – $65 million; 2.1 miles of mainlanes, frontage roads, and SL 335 third-level bridge at the I-40 interchange; awaiting funding

Segment B (southwest loop)

B-1 – 2 Miles

• Phase 1: $42.4 million; I-27 second-level bridge, SL 335 frontage roads, and grade separation at Coulter Road; under construction by Allen Butler Construction, Inc. (ABCI), Amarillo, with expected completion fall 2021
• Phase 2: $29.6 million; mainlanes, frontage roads, and grade separation at FM 2590; contract let in December 2020, construction expected to start spring 2021
• Phase 3: $25 million; SL 335 third-level bridge at I-27; awaiting funding

B-2 – 7.9 Miles

• Phase 1: $45.8 million; frontage roads; under construction by ABCI with expected completion spring 2022
• Phase 2: $50.6 million; I-40 second-level bridge and SL 335 frontage roads; under construction by ABCI with expected completion spring 2023
• Phase 3: $44.9 million; SL 335 third-level bridge at I-40 interchange, mainlane grade separation at BI 40-D, and ramps; expected to start construction in 2024
• Phase 4: $28.8 million; mainlanes and grade separations at arterials; awaiting funding
• Phase 5: $107.1 million; mainlanes and grade separations at arterials; awaiting funding

Segment C (northwest loop)

C-1 – 5.8 Miles

• Phase 1: $82.5 million; convert two lanes to four-lane divided; expected to start construction in 2023
• Phase 2: $115.5 million; convert four-lane section to freeway; awaiting funding

C-2 – 4 Miles

• $190 million; including U.S. 87 three-level interchange, mainlanes, ramps, and grade separations at arterials; phasing to be determined; awaiting funding

Segment D (northeast loop)

• $310 million; 8.3 miles of mainlanes, ramps, and grade separations at arterials and railroads; phasing to be determined; awaiting funding

Photos courtesy of the Texas Department of Transportation