Abstract Manager

Continuous Flight Auger Piles (CFAPs) were chosen as the preferred foundation alternative for the new Highway 400 Dunlop Street Underpass, marking the first use of CFAPs in a Ministry of Transportation Ontario (MTO) bridge project.  The new bridge, a 153.5 m long four-span steel box girder structure, will accommodate the future 10-lane configuration of Highway 400, replacing the existing two-span 54.4 m underpass constructed in 1951. 

Initially, driven steel H-piles were selected to support the new bridge. However, during the constructability review, it became apparent that installing steel H-piles would be extremely challenging due to traffic constraints requiring nighttime installation, which conflicted with the municipality's nighttime noise limitations. 

The design of CFAPs offered several advantages, making them the preferred foundation option. CFAPs provided larger axial capacities from shorter pile lengths, resulting in fewer foundation elements and a more cost-effective design with favorable schedule impacts. Additionally, CFAPs can be installed at lower noise levels compared to driven piles, and they reduce traffic impacts during the center pier installation. 
 
To optimize the design, the MTO conducted a full-scale static axial and lateral load testing program during the engineering and design phase, prior to construction. Two 26 m long sacrificial piles with diameters of 500 mm and 900 mm were tested. The test results indicated that these piles can provide ultimate axial capacities ranging from 5,000 kN to 8,000 kN per pile. 
 
This paper explores the engineering principles, benefits, limitations, and applications of CFAPs, along with advancements in technology and methods that enhance their reliability and efficiency.