The Genesee River flows through a deep gorge, affectionately known as the Grand Canyon of the East, located in Letchworth State Park, near the town of Portageville, New York.
For 137 years, an 819-foot-long steel and iron trestle railroad bridge rose 245 feet above the river. Part of Norfolk Southern’s Southern Tier Route between Buffalo and Binghamton, the Portageville High Bridge’s age was beginning to create supply chain inefficiencies. Rail car weights had to be reduced to 13,000 pounds below the standard, only single trains could traverse the bridge, and all trains were limited to 10 mph after a treacherous approach, a speed limit that added significant time to trade routes throughout Northern New York.
As such, the owner decided to replace the historic bridge with a new arch structure. WSP* served as geotechnical and foundation engineers of record for the first true steel arch bridge built for the railroad industry since the 1940s.
Starting in 2008, WSP* was retained to perform a preliminary geotechnical engineering design review and, over the next 10 years, provided services to support selection, design and construction of the new bridge, including:
- geologic and geotechnical mapping and subsurface exploration
- preliminary geotechnical engineering design recommendations
- foundation and geotechnical engineering services to support final design
- full-time, on-site construction support services in connection with the project’s specified foundation and geotechnical engineering elements
Over the years, the project construction team faced significant challenges. The site was highly inaccessible, as the new bridge was built into the sides of two vertical cliffs. With no direct access to the river, and no direct access to the foundation level, workers relied on cranes to access the arch foundations 100 to 120 ft below the gorge walls. In fact, during initial investigations, WSP* staff had to rappel down the cliffs to gather geologic and geotechnical data.
As the project progressed, so did the challenges. Rock blasting took place right next to the existing bridge – a fragile, cast-iron, steel-plated lattice structure. Without knowing how much stress the existing bridge could take, there was concern that blasting vibrations could potentially damage the structure, which could have potentially led to delays along a critical route for Norfolk Southern. To avoid this, teams used controlled, close-in blasting and conservative vibration limits, taking great care to keep train traffic moving during construction.
The unique project conditions were not the only Health, Safety, Security and Environment (HSSE) considerations on site. There were two natural, near-vertical rock slopes that required excavation. Even small pieces of gravel presented significant hazards to workers, and the structure, if they fell. As part of the permanent design, the team included rock slope stabilization elements in the design for both slopes, including rock dowels, shotcrete (pneumatically applied concrete) and rockfall drapes.
The new bridge, built 75 feet south of the old structure, is a 963-foot-long single-track crossing with a ballast-filled concrete deck. The bridge’s arch design minimizes the railroad’s environmental footprint in the Genesee River and frames a striking view of the river gorge. Trains can safely cross the bridge going up to 30 mph and the approach on both sides boasts wider embankments.
The project received the Engineering News Record (ENR) New York Highway/Bridge Award of Merit in 2018, and a National Recognition Award for exemplary engineering achievement from the American Council of Engineering Companies’ (ACEC) Engineering Excellence Awards (EEA) in 2020.
WSP* is proud to be part of the project that built this historic and scenic bridge that allows trains to keep chugging to destinations throughout the northeastern U.S.
* This work was performed by Golder professionals who joined WSP in an acquisition completed in 2021.