US-281 Bridge over the Colorado River. Marble Falls, Texas

Awards:

  • 2015 FICE Engineering Excellence Grand Award. Structures.
  • 2015 ACEC Engineering Excellence Honor Award.
 

Services Provided by FINLEY:

  • Bridge Design (Redesign Of Segment Lengths) And Construction Engineering
  • Preparation Of Integrated Shop Drawings
  • Falsework And Temporary Works Construction And Geometry Control
  • Design And Detailing Of Temporary Works
  • Construction And Geometry Control Manuals
  • Stressing Data For The Post-Tensioning Tendons
  • Design Office Support During Construction
 

Owner:

Texas Department of Transportation
 

Client:

Archer-Western Contractors
 

Photos:

Courtesy of Texas Department of Transportation and Archer-Western Contractors
 

Start date:

2012
 

Completion date:

2014
 

Cost:

$29.7M
 

Specifications & Details

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

The Texas Department of Transportation wanted to replace the Lake Marble Falls bridge with two new bridges to improve safety and mobility.

The new twin US281 bridges carry two lanes each in opposite directions to replace a functionally obsolete steel truss bridge built in 1936. The 958’ long bridge is a 3-span (274’-410’-274’), variable depth, cast-in-place segmental superstructure with a 47’-wide deck with 6’ wide sidewalks and a fully lighted substructure. The bridges were built utilizing the balanced cantilever construction method with end spans constructed on falsework. The box depth varied from 23’-0” at the interior piers, to 9’-6” at the end spans, and a variable superelevation up to 5.5%.

It is the second longest main span for a segmental bridge in Texas, and the only segmental bridge in Texas with no approach spans.

The FINLEY-Archer Western Contractors Team proposed design modifications and proposed means and methods met all project requirements, including a stunning signature bridge that was more efficient to build which saved $2 million dollars; 5% below TxDOT’s estimate.  A major change to the design was the modified pier table and segment lengths. Because the river bed and adjoining cliffs are hard limestone and the lake is a major tourist attraction, TxDOT wanted the bridge to have the fewest piers necessary in the water. This innovative approach reduced the pier table length by 40% saved approximately 12 weeks off the construction schedule. The design modifications included the use of the contractor’s form traveler from another jobsite and were available for this project. This provided a cost savings of $750,000. The cast-in-place segmental construction method used form travelers which required less labor-intensive falsework to be built to support the bridge during construction and reduced several months off the project schedule. Traditional cofferdams could not be used. The design modification specified a hanging precast concrete footing form from the drilled shaft casings. The “bathtub” style form was precast on-site and then lowered into the water with wall forms already attached, providing for a dry work environment to construct the footing. The bathtub dewatering design allowed the entire column pour in dry conditions. Use of FINLEY’s proprietary software made it possible to develop details quickly to meet the demanding schedule, including integrated segment drawings combining reinforcing bars, bolt inserts (for utilities), electrical conduits, etc., all into one drawing.

The design modifications and proposed means and methods met all project goals and provided a stunning signature bridge which was more efficient to build.
 

Photos courtesy of Texas Department of Transportation and Archer Western Contractors.

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