The USD 28.65 million project for the Texas Department of Transportation required Finley Engineering Group, Inc. and Archer Western Contractors (FINLEY & WALSH) to replace a functionally obsolete steel truss bridge with twin, 958-foot-long bridges, each carrying two lanes in opposite directions. The hard rock riverbed of the Colorado River, close proximity to the existing bridge—which had to remain open for traffic throughout construction, and need to maintain an open water channel for boating activity precluded the use of traditional steel cofferdams needed to build forms for the bridges. To accommodate the complexity and constraints of this specialized construction project, FINLEY & WALSH relied on Bentley’s adaptable bridge design and analysis software.
FINLEY & WALSH designed the bridges with an innovative approach using a balanced cantilever construction method with end spans constructed on falsework, reducing the need for drilling in the rock riverbed. The team relied on RM Bridge and MicroStation to address the complex bridge geometry and design modifications. Using Bentley software, FINLEY & WALSH designed the pier table falsework with bolted connections to ease installation and removal. The flexible and interoperable BrIM processes allowed for integrated segment drawings and a time-dependent, staged analysis to meet the demanding schedule.
Integrating RM Bridge with MicroStation for segment geometry control and modeling, FINLEY & WALSH quickly modified the bridge design to meet the aggressive schedule, saving USD 2 million, 5 percent below the Texas DOT estimate. The design modifications improved construction efficiency, reduced costs, and minimized risk. Reusing form travelers from another job site saved USD 750,000 in costs and several months time for design and fabrication of new travelers. The top down design and construction method provided a safer environment for workers, watercrafts, and the traveling public.
Using Bentley software, the team quickly integrated bridge segment drawings, combining reinforcing bars, bolt inserts, and electrical conduits into one drawing, enhancing project delivery time. RM Bridge provided stringent geometry control to maintain consistency as each bridge segment was added, and allowed for actual camber measurements to be recorded during construction for immediate modification. The interoperability of Bentley software enabled FINLEY & WALSH to implement design modifications to meet all project goals while saving the Texas DOT USD 2 million.