H&H served as a key design subconsultant for the accelerated design-build replacement of major portions of the 133-year-old Metro-North Railroad Park Avenue Viaduct in Manhattan. This vital structure carries four Metro-North tracks and supports approximately 750 trains and 260,000 passengers each day. The project replaced 49 spans, comprising 196 bridge structures across the four tracks, including the steel superstructure, columns, foundations, tracks, and related systems, as part of a major state-of-good-repair initiative for MTA Construction & Development and Metro-North Railroad.
H&H was the Engineer of Record for the new substructures and foundations, which included 50 bents supported by more than 900 rock-socketed micropiles. The work was performed within significant constraints, including limited overhead clearance and space beneath the active viaduct, an accelerated schedule, and the need to minimize disruptions to Metro-North service, local traffic, and community parking. To address these challenges, H&H collaborated closely with the contractor to develop innovative solutions, including a specialized casing overburden drilling system and the use of a down-the-hole hammer to improve drilling efficiency.
The substructures and foundations were designed to accommodate heavy rail loads, seismic forces, and future utility work. H&H also worked with the contractor to develop efficient reinforcing steel solutions and select self-consolidating concrete mixes that facilitated construction within the highly confined space beneath the viaduct.
Major structural replacement work was completed in July 2026, 60 months ahead of schedule and $195 million below the original project budget. Over 28 weekends, the project team replaced more than 12,600 feet of railroad while maintaining full Metro-North service and completing the work without delaying a single train. This significant milestone strengthened the long-term reliability and resiliency of a critical corridor that carries 98 percent of all Metro-North service and every train traveling into and out of Grand Central Terminal.
