PTIA I-73 Taxiway Bridge

NCDOT launched a $176-million design-build project to reduce congestion and provide better access to the increasingly busy Piedmont Triad International Airport (PTIA) in Greensboro, North Carolina. A key component of the project consisted of a Taxiway Bridge over future I-73 to connect hundreds of acres of owned property to PTIA’s existing airfield and runways.

The taxiway bridge structure would be supported by three interior bents, with an end-bent at each end. Morrison Engineers was hired to design and build a micropile foundation system to reinforce the interior bent footings, as well as permanent shoring to aid in the controlled excavation of the two end-bent walls.

Morrison Engineers also installed two 8,000-sq-ft drilled and grouted soil nail walls using a permanent shotcrete facing to allow for the excavation of the center of the job site, and make way for bridge and highway construction. The two walls, approximately 20 ft tall and 450 ft long, were installed in 5-ft lifts, from the top down, to safely bring the existing grade down to the proposed subgrade elevation. Each wall consisted of approximately 440 soil nails, totaling 13,000 linear feet and were designed to withstand the anticipated earth pressures and surcharge loading imposed by jets approaching the taxiway bridge. We performed approximately 50 proof tests on the production soil nails to verify design capacities were met during installation.

Location: Greensboro, NC

Owner: NC Department of Transportation

Client: Flatiron and Blythe Development, a Joint Venture

Systems / Methods Used:

• Permanent Shoring System

• Drilled and Grouted Soil Nail Walls with Shotcrete Face

• Deep Micropile Foundation