SPANNING THE 'GRAND CANYON OF THE EAST' Foundation Design for the Genesee Arch Bridge Project

摘要

Replacement of the Portageville High Bridge (High Bridge) over the scenic Genesee River Gorge with a new steel arch structure was a complex undertaking, made possible by meticulous consideration of its foundation design. The new bridge represents the first true steel arch bridge structure built for the railroad industry since the 1940s. Upon its completion, the bridge was renamed the Genesee Arch Bridge. The bridge lies within the southwest part of Letchworth State Park, often referred to as the "Grand Canyon of the East', about 40-miles southwest of Rochester, New York. By the late 1990s, the High Bridge was showing its aged condition and need for replacement. After acquiring the bridge, Norfolk Southern decided to replace it with a new 2-hinged, spandrel-braced steel arch structure. Significant site constraints complicated bridge construction, as any activity could not adversely impact the river or park. As a result, the new bridge was designed utilizing cantilevered construction methods and its foundations were cut upwards of 120-feet into the gorge sidewalls. Bridge foundation design required extensive evaluation, including a detailed subsurface exploration program to characterize ground conditions. Engineering design evaluations were undertaken to address ground conditions that had the potential to affect the new bridge's integrity, including arch skewback foundations, micropiles, rock excavations utilizing controlled rock blasting, rock slope reinforcement and stabilization, rockfall hazard mitigation measures, and railway approach embankments. Construction of the new bridge commenced in November 2015 and opened to railway traffic in December 2017.