Canvassing With Concrete

Ribbons of Concrete Roads Wind Through Central Texas

By Rob Patterson

Texas is leading the nation in highway construction, and one of the epicenters of work is Central Texas, where a number of current projects involve high complexity and innovative approaches to working with concrete. Some of those methods may become more common based on their successful use on these jobs.

Austin Bridge & Road, an operating company of Dallas-based Austin Industries, is more than 85 percent complete on Section 8 of the new SH 45 toll road in north Austin, a job that includes a five-level interchange with U.S. 183 and a toll plaza stretching across 22 lanes, as well as extensive utility relocation along the 2.5-mi. stretch. Construction started in December 2003 on the $105 million project. It will be completed by the end of next month.

The first phase of the project involved relocating electric, gas, water and telecommunications utilities along the SH 620 corridor that SH 45 is replacing. Austin Bridge & Road installed 14,000 ft. of new water and waste conduits, 40,000 ft. of storm sewer and relocated aerial electric and cable lines into an underground duct bank. Four lanes of asphalt access road were then built to carry SH 620 traffic before work could begin on the new roadway.

"We had a lot of contractors, subcontractors and outside utility companies working simultaneously," said Mike Brown, project manager for Austin Bridge & Road. "The coordination was more involved than normally required."

The most complex aspect of the project was the interchange. Austin Bridge and Road built four of its levels while Austin-based J.D. Abrams, the contractor on the intersecting section of the U.S. 183 project, built another level. "It is more than 100-ft. tall," said Robert Vallejo, general superintendent for Austin Bridge & Road. "We had to lift massive concrete and steel girders around obstacles and existing roads."

The interchange required 14 man lifts and 12 cranes to perform the work. "Because of the existing traffic, it was difficult to stage all of the equipment," Brown said.

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Liquid nitrogen was used to cool the concrete for all the mass pours on the footings and pilings (see "Beating the Heat," page 67). The contractor installed 1.2 million ft. of bridge deck on the structure.

Austin Bridge & Road also constructed an operations building and a 400 ft. long 10 ft. by 10 ft. box culvert underneath the barrier plaza for its communications and control systems and to give staff access to stations.

A 190-ft. section of fiberglass-reinforced jointed concrete paving from 11- to 17-in. thick was installed around the toll plaza. The remainder of the SH 45 roadway is 11-in.-thick steel-reinforced concrete.

The contractor poured 125,000 cu. yds. of concrete overall on the project.

Brown said the sheer volume of the job and its schedule were the project's major challenges. "TxDOT has a goal of early completion," he said. "The efforts of our people reflect that sense of accountability to meet and exceed these expectations."

On a nearby stretch of road, a joint venture of San Antonio-based Zachry Construction Co. and Gilbert Texas Construction of Austin has been performing similar work on a 3.5-mi. toll-road extension of Loop One. Construction began in August 2003, and the $108 million project is scheduled to complete by the end of next month.

The job includes three bridges, six ramps, a main toll plaza and three ramp plazas. A section of FM 1325 and associated utilities had to be relocated as part of the project.

Zachry/Gilbert poured 107,000 cu. yds. of steel-reinforced concrete and more than 3,600 cu. yds. of fiberglass-reinforced concrete at the plazas. The job included 1.1 million cu. yds. of excavation, 2 million cu. yds. of embankment and 500,000 cu. yds. of precast concrete walls.

The volume of work was a challenge for Zachry/Gilbert. Recovery work following the 2005 hurricanes impacted the availability of utility crews. "We had to stretch our equipment, manpower and materials," said Jean Abiassi, director of operations for Zachry's highway/heavy group.

TxDOT hired PBS&J of Miami to act as a management and inspection consultant on both jobs due to the amount of highway work being performed in the Austin area. "That added a new dimension to doing work with TxDOT," Brown said.

For TxDOT, the coordination of multiple contractors working simultaneously on adjacent and nearby projects wasn't easy. Minimizing the effects of work on businesses and residents and keeping traffic flow going were concerns for the agency. "The projects will result in a big improvement in traffic flow in the area," said Jeff Tolson, TxDOT project supervisor. He added that the projects are ahead of schedule and under budget.

About 100 mi. north of Austin in Waco, the $44 million IH-35/Loop 340 (SH 6) interchange reconstruction project was a test program of an alternative approach to creating and erecting a precast-concrete bridge on four of the five bridges. Archer Western Contractors of Arlington set up a precasting yard about a mile from the job where column liners were cast and deck and rails were placed on tub girders that were assembled into the bridge deck.

To achieve the decorative design on the columns, they were poured into upside-down forms with one layer of rebar using 533 cu. yds. of concrete. After being set on the site, the interiors were poured in place.

The bridge spans were laid out in the yard, using 104 separate tub girders. The decks were poured and, on the outside girders, rails attached. Then the modular pieces - each 115 ft. long and 8 ft. wide and weighing about 185,000 lbs. - were separated and transported to the site.

Some creativity was needed to haul and maneuver the large pieces. "We used steerable dollies and John Deere

tractors," said Bill Heathcott, senior project manager for Archer Western.
It took just two night shifts to lift all pieces into place using two cranes. All that was required next was a closure pour to a 12-in. gap between the beams.

"In a typical operation you'd then have to set overhangs and decking after placing the beams, and both operations would impact the traffic," Heathcott said. "You'd have to follow with a deck pour and setting the rails. The only time traffic was impacted was the beam set. The closure pours were made without traffic closure and the rail and deck was cast prior to erection in the precast yard."

Two older bridges were demolished, and one new bridge connecting eastbound Loop 340 with northbound IH-35 was built using conventional methods. Archer Western also rerouted utilities and performed extensive site work on the project, performing 260,000 yds. of excavation, building 230,000 yds. of embankment and pouring 138,000 sq. yds. of concrete paving for the on-grade ramps.

"I think the setting of the beams and the deck was a success," Heathcott said. "We bid a job in Bell County recently that had a similar deck orientation." But precasting columns didn't save time, he added.

"We feel that the test was a success, and were pleased that we were able to limit the closures and detours," said John Jasek, Waco area engineer for TxDOT.

About 50 mi. southeast, on a $26 million job on SH36 in Cameron, James Construction of Baton Rouge, La., performed a variety of tasks including the demolition of a 4,200-ft., vintage 1940s bridge across Little River and constructing two new bridges. The firm built four mi. of divided concrete roadway and constructed a new railway bridge over the road.

The three-phase project started in August 2004 and is more than 50 percent complete with a July 2007 finish date.

The first phase included the construction of the first new 3,000-ft., two-lane bridge to carry SH36 traffic and allow demolition of the old bridge. The contractor was concerned about safety during the demolition of the old steel girder bridge while it still perched precariously above the river.

Engineered Explosive Services of San Antonio solved the problem by blasting the pilings of the bridge after the center span over the river was removed. Most of the structure was dropped to the dry riverbed where it could be safely demolished.

During phase two, the second two-lane bridge was built. The two bridges were constructed on concrete pilings with precast concrete and steel beams and 244,000 sq. ft. of concrete bridge deck.

A 150-ft. reinforced concrete railroad bridge was built over the SH 36 roadway. At 17-ft. high, it has three ft. more clearance than the old railroad bridge, which was demolished after tracks were rerouted.

The final phase was construction of the four mi. of expanded four-lane on SH 36. More than 50,000 cu. yds. of concrete was poured atop a base of flex mix and asphalt.

"The variety of work and trades made it an interesting project to work on" said Ken Janke, Texas division manager for James Construction.

"Once the project is completed, it will significantly improve access on SH 36 to the Cameron area," said Bob Cochran, TxDOT area engineer for the Milan District.