Photo courtesy of Zachry Construction
Zachry Construction has made several upgrades and improvements on the Texas Department of Transportation’s (TxDOT) SH 71 East Corridor project in Greater Austin that is improving road safety and improving traffic flow.
Zachry Corporation is months away from completing construction of the Texas Department of Transportation's (TxDOT) SH 71 East Corridor project in Greater Austin that is improving road safety and improving traffic flow. SH 71 serves as a major corridor for motorists traveling to and from the Austin-Bergstrom International Airport, the city of Bastrop and other central Texas communities.
The first phase of this project — valued at $65 million — began in February 2021 as crews began upgrades to Ross and Kellam roads. The work zone, which spans 3 mi., covers the highway from SH 130 to Norwood Lane. The project is expected to be delivered in late spring/early summer, weather permitting.
Zachry crews are constructing two new overpass bridges on SH 71 over the existing signalized intersections at Ross and Kellam roads that will improve mobility by allowing through-traffic on SH 71 to flow through the area without stopping. New frontage roads will allow local travelers to access to Ross and Kellam roads and improve cyclist and pedestrian infrastructure.
The project was designed by Gunda Corporation, which was acquired by Ardurra while this project was under construction.
Bridge Construction
"The two overpasses over Ross Road and Kellam Road remove two signalized intersections that stopped high speed traffic in both directions, which should reduce local traffic conflicts with thru traffic," said Aaron Vrazel, Zachry's project manager. "Several median crossovers are also being removed with the hopes to lower crossing traffic incidents. Business and residential driveway access now has dedicated frontage roads that will be posted for 45-mph instead of trying to turn and merge with high-speed traffic on the main lanes.
"Ross Road is a major corridor for local traffic and especially for Del Valle ISD with a high school, middle school and elementary school, so getting thru traffic up and over the SH 71 intersection at Ross Rd reduced the peak traffic conflicts at this critical intersection," he added. "Event traffic for Circuit of the Americas now has better access from to Kellam Road via the SH 71 frontage roads rather than blending with through traffic on the main lanes."
Precast/prefabricated TX34 and TX54 girders were used.
"These wide flange girders are wide enough to act as support for the bridge overhang concrete that would normally require temporary falsework," said Vrazel. "These wide flange girders allow for the deck concrete to be placed without installation and removal of that separate overhang falsework/formwork. This approach accelerated the deck construction and reduced the need for lane closures for traffic below the overpass bridges.
"Footings and tie beams were added to provide support on the existing SH 71 eastbound and westbound bridges over Onion Creek adding resiliency for future flood events," he added. "Along with the footings and tie beams, 18-inch and 30-inch rock riprap, concrete riprap, and interlocking articulating concrete blocks were installed to protect the bridge foundations from scouring during high flow events."
Photo courtesy of Zachry Construction
"Prestressed concrete I-Girders [are being used] because prestressed concrete is the most durable, reliable and strongest concrete that is widely used for the construction of mega buildings and bridges," Glynda Chu, a public information officer of TxDOT's Austin District, said. "Prestressed concrete is very beneficial to construct crack-free structural members and tackle shrinkage and temperature effects. Prestressed concrete allows the construction of longer span beams and girders in addition to increase the ultimate load carrying capacity for the same member cross-section."
"All of the bridge substructure, bridge superstructure and overhead sign column work is cast-in-place," Vrazel said. "Falsework was utilized for the bridge cap construction as a part of the substructure and for the overhang on the westbound Onion Creek widening, but the wide flange beams at the four Ross and Kellam overpass bridges allowed for that overhang falsework to not be utilized."
Most of the earth moving equipment is Cat, including a 336 excavator; D5 and D4 dozers; an 84-in. vibratory roller; an RM400 mixer; a 150 motor grader; a 950 loader, as well as standard pieces. Dozer and motor graders paired with Trimble machine control and GPS also are being used. Structures crews are mainly utilizing JLG and Skyjack manlifts, Xtreme 1255 12k telehandler and a Grove rough terrain crane.
The frontage roads are approximately 1.5 mi. of two-lanes in each direction, eastbound and westbound. The frontage lanes are asphalt while there are 2.5 mi. of main lane and ramp construction. Approximately 1.7 mi. of the mainlanes have been completely reconstructed with 11-in. continuously-reinforced-concrete paving (CRCP).
"The local soil is a high PI clay that requires treatment with lime or replacement to be used for the roadway," said Vrazel. "Frontage roads get 8 inches of lime treatment, then 8 inches of flex base and 6.5 inches of hot mix asphalt [HMA] with curb and gutter on each side. The main lanes have two feet of a select embankment material that has the top six inches treated with cement that is capped with an asphalt bond breaker prior to the CRCP being placed.
TXDOT standard mixes including Class B, A, C, S and P.
"Substantial drainage was installed including removing and replacing all of the cross culverts from ROW to ROW," said Vrazel. "Then parallel drainage was added along the curb lines of the frontage roads and ditch lines on each side of the main lanes and the main lane median."
Zachry had one large grading crew and two structures crews, along with various subcontractors performing the work on the project.
For improved cyclist and pedestrian infrastructure, 10-ft. wide shared-use-paths (SUP) are being constructed along the eastbound and westbound frontage roads from Ross Road to Kellam Road.
"These SUP sections are connected to each other and the adjacent sidewalks with sidewalks and ADA curb ramps at the Ross Road and Kellam Road intersections," said Vrazel. "There also will be upgraded protected signalized pedestrian crossings at the frontage road intersections to allow for access along most of the project length."
During peak times, westbound traffic in the morning and eastbound traffic in the evening would back up at least a half-mile at the old signals.
"The free flow overpasses at Ross and Kellam roads decrease these backups and allow increased mobility of traffic," said Vrazel. "Dedicated frontage roads allow for better access to future developments from Onion Creek to just past Kellam Road."
According to Vrazel, revisions were needed to a few of the steps in the traffic control plan in order to complete the work as designed.
"Zachry and TXDOT partnered throughout the project to utilize the Request for Information [RFI] process to come up with the most efficient solutions to these conflicts," Vrazel said. "Temporary shoring was implemented in a couple of areas to allow for work to proceed where the width needed for construction did not allow for vertical differences between the existing and proposed pavement sections. Extended night and weekend lane closures were also utilized to complete work that was needed to maintain two through lanes which addressed some of the traffic control plan conflicts."
In regards to the lifespan, Chu stated that "typically the design life for new bridge construction is approximately 50 to 70 years."
To manage traffic during the construction, TxDOT did phased construction using DMS signs, message boards and construction signing to alert the traveling public.
"Traffic is flowing extremely well now that the eastbound and westbound overpass bridges have been completed," said Chu.
"Since the opening of the SH 71 main lane overpasses, it is challenging to ensure traffic stays within the 55-mph work zone speed limit," Vrazel. "The traffic control plans are utilized to bring materials and equipment in and out of the work areas. Gaps are created in the portable concrete traffic barrier [PCTB] to allow for access to homes and businesses. These access points are also utilized by project personnel to enter the work area from the travel lanes if deceleration and acceleration areas can be created.
"For this job, TxDOT has allowed Zachry to have multiple construction entrances to the job to allow for the movement of equipment, materials, storage space, to minimally impact the traveling public while constructing the job," said Chu.
The project is not without its challenges.
"In addition to the traffic control plans, maintaining access has been a main focus recently," said Vrazel. "Zachry coordinates with businesses and homeowners to build driveways in phases or provide alternate access to keep the project moving but to also maintain access at all times. The project is currently in the later phases having completed the eastbound frontage road and both eastbound and westbound main lanes over Ross and Kellam Road. The focus now is to complete the westbound frontage road."
Zachry and TxDOT continue to partner to reduce utility conflicts and mitigate delays.
"Most of the project was very accessible, but one area that had tight access was the East abutment and East bank of the Onion Creek bridges where the Right-of-Way [ROW] was adjacent to the tow of the existing bridge embankment," said Vrazel. "This area posed some access and erosion control challenges that were managed weekly to ensure that work could be completed, but also kept the creek protected from sediment discharge. We have an effective working relationship with TxDOT and the construction-engineering-inspecting [CEI] firm Atkins-Realis."
The work on the overpass bridges has been completed.
"There are four, three span, two-lane bridges that are about 300 feet long with a 10-foot and 4- foot shoulder," said Vrazel. "There also was a 14-foot by 10-inch widening to the 750-feet long westbound SH 71 bridge over Onion Creek that allowed for an additional merge lane from the Ross Road entrance ramp down to the SH 130 northbound frontage road. The westbound Onion Creek bridge widening and foundation improvements along with the eastbound frontage road were the first areas started on the project because they were outside of the existing lanes of traffic.
Photo courtesy of Zachry Construction
"The two eastbound overpass bridges were constructed at the same time and then the two westbound overpass bridges were constructed at the same time," he added.
The eastbound SUP was completed in January 2023 and the westbound SUP construction is just beginning with the goal of completing in the spring 2024.
Busy days have many Zachry and subcontractor workers on-site.
The main subcontractors for the project are Aaron Concrete Contractors along with Austin Formula Utilities for the underground drainage/curb and gutter; Texas Highway Walls for the wraparound MSE walls at the intersections; The Levy Company for the electrical/signals and the large signs; Lone Star Paving for the HMA work; Flasher Equipment Company for pavement markings; M&D Industries of Louisiana for the drill shaft foundations; and Roadway Specialties Inc. (RSI) for guardrail and small signs.
The amounts of materials generated by excavation and demolition operations have not been finalized.
"Asphalt, concrete and reinforcing steel removed from the project are recycled or re-used," said Vrazel.
New materials include more than 42,000 cu. yds. of concrete, approximately 2,000 tons of reinforcing steel, more than 44,000 tons of asphalt, 4,100 linear ft. of 24-in. water line, 3,400 linear ft. of box culvert ranging in size from 4 ft. by 4 ft. to multi-barrel 10 ft. by 5 ft., and approximately 26,000 linear ft. of reinforced concrete pipe (RCP) ranging in size from 18 in. to 42 in.
For a multi-year project such as this, maintenance is crucial for maximum production.
"Equipment fluids, lubrication and undercarriage components are monitored for normal and excessive wear that may indicate issues with machines," Vrazel. "Proper lubrication and daily inspections by our operators help keep equipment downtime to a minimum."
Additional Construction
Planning is ongoing for the Tucker Hill Lane ($64 million) and Pope Bend Road ($53 million) projects, the second phase.
"Various improvements have been evaluated with the goal of upgrading SH 71 at these intersections," said Chu.
The proposed projects would include two new overpass bridges on SH 71 over the existing signalized intersections at Tucker Hill Lane and Pope Bend Road, one-way frontage roads within the project limits and improved and expanded bicycle and pedestrian infrastructure.
Photo courtesy of Zachry Construction
"The projects require 24.5 acres of right-of-way at the Tucker Hill Lane intersection and 11.09 acres at the Pope Bend Road intersection," said Chu. "The acreage at Pope Bend Road includes 2.13 acres in McKinney Roughs Nature Park, a park area used by the public, which is subject to Chapter 26 of the Parks and Wildlife Code. No displacements are anticipated for either of the proposed projects."
Both projects are scheduled to go out for bid in 2027, once funding is secured.
The constraints analysis and development of conceptual roadway design alternatives has been completed, as has the environmental study and schematic design. The preparation of the final design, right-of-way acquisition, and utility adjustments is under way.
The SH 71 at FM 1209 project, the third, is also in the planning stage.
"The proposed project is needed to address increased congestion along SH 71 due to population growth and traffic volumes," said Chu. "The purpose of the proposed project is to improve mobility and reduce congestIon along SH 71 at FM 1209."
The proposed plan is to construct a new overpass bridge on SH 71 over the intersection at FM 1209.
"This would improve mobility by allowing SH 71 through-traffic to flow through the area without stopping," said Chu. "In addition, new frontage roads would be built within the project limits to allow local travelers access to FM 1209. Bicycle and pedestrian accommodations would also be improved and expanded, as a part of this proposed project."
Currently, the final design, right-of-way acquisition and utility adjustments phase is under way. Once done, the construction can begin.
The cost is estimated at $45 million, with plans to go out for bid in 2029 when funding is secured. CEG
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