What does it take to transform one of the most-congested roadways in San Antonio, Texas, into a fast-moving expressway?
In the case of U.S. 281 in Bexar County, the answer is $370 million, almost two decades of planning, and five years of construction – but the end result will turn the 8-mile divided highway filled with traffic signals into a full expressway with two general-purpose lanes, one high-occupancy vehicle (HOV) lane, continuous frontage roads for local access, and bicycle/pedestrian facilities in each direction.
General Contractor Webber Construction of Houston, Texas, started the project’s 3.8-mile, $192 million phase one in August 2017. With 43 months to finish and 19 bridges to construct, Webber and their 40-plus subcontractors sent 200 workers to the jobsite. Crews regularly work 24 hours a day, six days a week, with occasional Sunday hours. Ongoing utility relocations and the discovery of hidden karst features in the rocky terrain often require crews to move to a different location.
Despite those challenges, the first phase of the project remains ahead of its 2021 completion schedule. The second phase will begin next March, with substantial completion projected in spring 2023.
How to Keep Traffic Moving
Planning for the U.S. 281 upgrade, which starts at Loop 1604 and extends north to the Bexar/Comal County line, began many years ago. In 2004, when money became scarce, toll lanes looked like the only way to complete the work. However, the passage of Proposition 7 in 2015 and the Texas Clear Lanes Initiative provided funding that allowed the project to move forward without tolls.
Webber won the low-bid contract for the first phase of improvements in February 2017. In addition to new frontage roads and reconstructed expressway lanes, their work includes 15 bridges over cross streets and four direct connector bridges that will tie eastbound and westbound Loop 1604 to the northern lanes of U.S. 281. An elevated T-ramp will connect the expressway to an existing VIA mass transit parking garage. The project also adds an intelligent transportation system (ITS) with cameras and two dynamic message boards.
First-phase construction is scheduled for substantial completion by March 2021. Webber will receive a significant incentive if they finish at least 100 days ahead of schedule. The project also includes seven other major milestones to keep traffic flowing, with incentives and disincentives tied to each one.
Throughout the project, the Texas Department of Transportation (TxDOT) aims to equal pre-construction service, keeping the same number of lanes open to drivers. So far, the project team implemented dozens of traffic control plan changes in order to postpone closure of the first ramps and a U-turn.
“We haven’t had much disruption to traffic so far because we had enough right-of-way to build the new frontage roads on each side of the existing roadway,” said Pete Garza, Resident Engineer for the project’s Program Manager VRX, Inc., of San Antonio, Texas. He expects traffic to move onto the new frontage roads by early spring, then crews will begin building the new expressway lanes and overpasses.
To keep traffic moving, “There are no daytime lane closures allowed during the week and we don’t allow any lane closures during the holidays or special events,” Garza said. “We do allow lane closures overnight and from Saturday morning to Monday morning, but there are disincentives if crews don’t pick up the temporary lane closures by 5 a.m.”
When Karst and Utilities Get in the Way
One of the biggest challenges in the fast-growing area was relocating utilities. “There’s been a lot of coordination with the utility companies for years before construction began to move conflicts with the proposed plan,” Garza said.
Webber and local utility companies continue to work on water, wastewater, gas, electrical, telecommunication, and drainage lines. “At one time we had 12 millers out there working to trench through the area’s rock formations in order to bury the lines,” Garza said.
The location within the Edwards Aquifer Recharge Zone required numerous environmental permits before construction began. During excavation and drilling, crews uncover previously unknown karst features that need special attention.
“Sometimes we find four karst features in a week, and sometimes we go a couple of weeks without encountering any,” Garza said. “If we encounter a volume bigger than one cubic foot, it triggers a 28-day survey required by the U.S. Fish and Wildlife Service. The survey ensures there aren’t any endangered species in the karst feature. So far we’ve had 28 surveys and not encountered any endangered species.”
After the survey, the Texas Commission on Environmental Quality must approve the closure of any karst feature. Meanwhile, contractors move to work in another area. “We’ve jumped around a lot,” Garza said.
The frontage roads, six expressway lanes, and multitude of bridges allow ample opportunities for work despite the disruptions. The bridges alone require 1,500 drill shafts and more than 40 retaining walls. With all the structural concrete for the bridges, “We calculated that we could fill up a football field over 50 feet tall,” Garza said.
Preserving Natural Features
For the project’s retaining walls, designers wanted to preserve natural geologic formations wherever possible. To accomplish that, “We’re using four different types of retaining walls,” Garza said. “MSE walls are precast offsite and trucked in. They’re also building cast-in-place retaining walls, soldier pile walls, and soil nail walls. We have several stone-face walls where we don’t need a concrete retaining wall in front; the rock is stable enough to leave as is after we cut down for the new grade of the road.”
In the embankments, “Webber will utilize a lot of the millings from the rock excavation,” said Jon Green, TxDOT’s Project Manager. “It’ll be a very good material – 149 pounds per cubic foot – so it’s just about as strong as concrete. As they excavate, they pulverize the rock onsite then haul it to a stockpile. Once we switch traffic they’ll bring it back and place it at the bridge abutments for the main lane overpasses.”
Project specifications also included reuse of other materials. For instance, “To recycle some of the asphalt we take out, we’re incorporating it into our asphalt mix design on the frontage roads,” said Carlos Ayala, VRX Resident Engineer.
As Webber continues work on phase one, Zachry Construction Corporation of San Antonio, Texas, will start the $178 million second phase in March 2019. That project will tie into the northern edge of phase one and proceed approximately four miles north, finishing in spring 2023.
Key Project Personnel – Phase One
By the Numbers
The first phase of the U.S. 281 project in Bexar County includes:
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