The Replacement of the Park Avenue Viaduct: Micropile Foundations and Innovative Construction Techniques-PPT Presentation

PPT Presentation

Pdf Summary

The Park Avenue Viaduct is a 1.25-mile elevated steel structure carrying four Metro-North tracks through East Harlem. Because it serves nearly all Metro-North trains—about 750 trains and 220,000 customers on a typical weekday—its replacement is a major, carefully staged infrastructure project. The presentation covers two design-build phases: Phase 1, replacing the viaduct between 115th and 123rd Streets, and Phase 1N, between 127th and 132nd Streets.<br /><br />Both phases use micropile foundations to support the new substructure. Phase 1 includes 33 bents and approximately 600 micropiles; Phase 1N includes 18 bents and approximately 400. Foundation design had to account for variable subsurface conditions, seismic requirements, existing foundations, utilities, and restricted urban work sites.<br /><br />Construction relied on specialized methods, including geoprobing, a casing-and-drill system, short-mast crawler rigs for areas with less than 18 feet of headroom, and adapted pile sizes and work platforms where access was limited. The team also used load testing, video inspection of rock sockets, and geotechnical instrumentation to verify foundation quality and monitor performance.<br /><br />The testing program encountered a challenge when dual-jack tension tests caused unequal loading and unsafe test-frame movement. After five successful tension tests, the team shifted to compression testing and added sacrificial piles to provide reliable reaction capacity. The project illustrates how foundation design, testing, and construction methods must be adapted to complex geology and constrained sites while maintaining safety and performance.

Keywords

Park Avenue Viaduct

Metro-North

East Harlem

micropile foundations

design-build

foundation testing

geotechnical instrumentation

casing-and-drill system

restricted urban sites

load testing