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Lone star Record

inlandpipeHeldenfels ships 165-ft. girders to Central Texas Turnpike crossing

In a land known for size and highways, precast/prestressed producer Heldenfels Enterprises Inc. has added to the Texas Department of Transportation log a bridge bearing the state’s longest concrete girders subject to land transport. Just shy of 81 tons each, the AASHTO Modified VI beams form the 165-ft. center span of the 385-ft. County Road 179 crossing on SH 130/45, a toll route whose latest segments are scheduled for a 2012 opening.

The twin structure is built at a 47.5-degree skew. Seven of the 72-in.-deep, center-span girders support east and west lanes, with the same cross section on 110-ft. end spans also bearing Type VI Modified girders. Compared to the conventional Type VI profile, the modified girders have narrower webs, top and bottom flanges—the latter 26-in. wide.

Heldenfels crews cured the 165-ft. girders for 12–16 hours with wet cotton mats and tarps, observing test cylinder release strengths of 6,600–7,000 psi and 7-day breaks at 10,200 psi. Hirschfeld Industries of San Angelo, Texas, hauled the record girders with self-leveling bolsters and steerable wheel rear dollies to keep loads level in transit and navigate tight turns. The beams were just under TxDOT “super heavy” requirements for weight, and followed a route with no special restrictions.

The producer fabricated the CR 179 crossing’s 110-ft. and 165-ft. girders within a 2,424-piece contract for SH 45 and SH 130 Segments 5 & 6, which will extend by 40 miles a 57-mile toll route paralleling Interstate 35 to the east of Austin. SH 130 (north-south) and SH 45 North and Southeast (east-west) are the main routes in the Central Texas Turnpike System, under development since 2002.

SH 45 builder Archer Western Contractors required CR 179 girder delivery three weeks after fabrication. The contractor designed the structure with AECOM for toll road developer, SH 130 Concession Co. LLC. Plans and specifications were subject to approval of TexDOT, to which the Central Texas Turnpike System will eventually be transferred.

SH 130 Concession partners include Zachry American Infrastructure, a sister business of Heldenfels’ cement and aggregate supplier, San Antonio-based Capitol Aggregates. Mix designs especially conducive to accelerated fabrication cycles at the precast/prestressed producer’s San Marcos plant—about midpoint between Austin and San Antonio—include one using Capitol Type III cement, with above-normal tricalcium aluminate content, and Marble Falls quarry aggregate. Capitol Aggregates and Heldenfels quality control staff confer at least weekly on mix design performance.

— By Don Marsh