Fluor and Balfour Beatty Lead Challenging Design-Build 183 South Project
For many years, 183 South in East Austin, Texas, suffered from traffic congestion and outdated facilities. With funding hard to come by, the Texas Department of Transportation (TxDOT) partnered with the Central Texas Regional Mobility Authority. Through a design-build approach that allowed earlier financing and a plan that includes six toll lanes to repay construction loans, the project broke ground last April and will open in phases between 2019 and 2020.
The $743 million project covers 8 miles and will serve as a gateway to Austin-Bergstrom International Airport and as a bypass to Interstate 35. Design-build contractor Colorado River Constructors - a team of design and engineering consultants led by Fluor Enterprises, Inc., of Irving, Texas, and Balfour Beatty Infrastructure, Inc., of Atlanta, Georgia - will quadruple capacity, turning the four-lane divided highway into a total of 12 lanes. Three toll lanes in each direction and three reconstructed, non-tolled, general-purpose lanes in each direction will reduce congestion and delays.
In addition to the improved roadway, specialized landscaping will maintain the character of surrounding neighborhoods while $25 million of new pedestrian and bicycle facilities - including a 10-foot-wide, concrete shared-use path - improves connectivity.
Since the early 1980s, TxDOT looked at expanding the roadway originally built in the mid-1960s. "Pieces of the corridor had been expanded over the last 30 years, but there was never enough money to expand the entire corridor," said Steve Pustelnyk, the Mobility Authority's Director of Community Relations.
The design-build approach allowed the Mobility Authority to finance design and construction in one package. The Mobility Authority issued $252.2 million of toll revenue bonds. In addition, the federal government provided a $282.2 million loan under the Transportation Infrastructure Finance and Innovation Act and TxDOT provided loans totaling $60 million, plus a $146.3 million grant to help fund non-tolled elements.
According to Pustelnyk, "The design-build approach allowed us to expedite the design of the project and get it under construction sooner, which ultimately leads to faster completion and opening of the roadway."
As an added benefit, the design-build approach also mitigated one of the biggest challenges of the corridor - existing utilities. In total, $80 million of the project covers utility relocations, Pustelnyk said. "We have major water and sewer lines and a major hub for AT&T serving the whole country. Twenty different utility companies are in the corridor."
Design-build reduced the complexity of that challenge. "It allowed the contractor to overlap utility relocations with the construction activities; they managed that risk in order to accelerate the project," said Aaron Autry of Atkins Global in Austin, a general engineering consultant for the Mobility Authority. Autry serves as Project Manager for the 183 South Oversight Team.
Sixteen Lanes, Bikes, and Pedestrians Across Three Bridges
Another challenge of the project occurs at the Colorado River. Additional ramps in that area bring the lane total to 16, plus the shared-use path, crossing roughly a quarter mile on three separate bridges.
The design includes dramatically expanding an existing bridge for toll lanes in both directions, as well as southbound general-purpose lanes. Crews will demolish an older, pre-stressed concrete bridge that didn't fit the new alignment and build a wider bridge to carry northbound general-purpose lanes. In addition, the steel truss Montopolis Bridge will be converted to a bicycle and pedestrian facility.
"We divided the lanes to take advantage of structures that were already there; we didn't want to tear down everything and start from scratch," Pustelnyk said.
Colorado River Constructors phased the work, first widening the existing bridge in order to shift traffic off the bridge that will be demolished. "Once we get all the traffic moved onto the new expanded bridge, we'll begin work to demolish and rebuild the other bridge and eventually pull traffic off the truss bridge so we can start rehabilitating it," Pustelnyk said.
The truss bridge will require lead paint removal. Because the Colorado River generally remains shallow in that area, "We don't anticipate many issues with the water level, but there will be a lot of sensitivity to water quality and managing the environmental issues," said Pustelnyk.
Elderly Oaks and Context Sensitive Solutions
Environmental concerns in other areas also played a role in the corridor's design. For instance, "There was a longstanding commitment - initially with TxDOT, then we assumed that commitment as we took over the project - to protect as many of the large, elderly oak trees as possible on the south end of the project," Pustelnyk said. "It's uncommon to have oaks of that size and age because of the tough conditions they face here."
In addition to designing around the decades-old trees, "Our design-build contract specifies best practice measures we expect the contractor to comply with," Pustelnyk said. "The contractor put up special fencing and signage and protected the bark with boards. During construction they're mulching, watering, and doing some trimming. The contract includes some fairly painful liquidated damages if the trees are not cared for or die during the course of the project."
As part of the project's Context Sensitive Solutions design approach, enhanced landscaping with native grasses and large tree groupings provides unique identities to the many neighborhoods along the corridor. Nearly 2,000 native, drought-resistant trees will be planted throughout the corridor to reduce water consumption and help prevent soil erosion.
Miles of new bicycle lanes, sidewalks, and the shared-use path connect to the existing regional trail system. Although some motor vehicle crossovers were removed to provide a safer, smoother traffic flow, "We're constructing three new bicycle and pedestrian bridges to ensure mobility across the corridor," Pustelnyk said.
Underground, the design-build team needed special measures to deal with the natural clay soil. "We have to excavate a lot more and put in a lot deeper base material - as much as 6 feet underneath the concrete roadway - to be sure we have a good surface for the roadway that won't shift, crack, or fail in the future," said Pustelnyk.
When finished, the new 183 South Expressway will enhance quality of life for residents; improve access to the airport; and increase safety and mobility for commuters, bicyclists, and pedestrians.