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A leading full-service engineering firm renowned for our trusted, high quality, and innovative approach to solving complex challenges.

Snake Hill Road Bridge Replacement

Bridge Design Over CSX Rail Line, West Nyack NY

The Town of Clarkstown and Rockland County retained KCI, formerly McLaren Engineering Group, to provide bridge design, right-of-way (ROW) services, and construction inspection for the Snake Hill Road Bridge (BIN 3345780) over the CSX River Line in West Nyack, New York. The bridge, jointly owned by Rockland County and the Town of Clarkstown, had reached approximately 30 years of service when deterioration in critical load-carrying components began to affect its structural performance.

Our work included designing a new bridge superstructure and rehabilitating the existing substructure, extending the bridge’s service life by approximately 50 years while improving safety and meeting modern clearance standards over the active railroad corridor.

Snake Hill Road Bridge in West Nyack, NY

Snake Hill Road Bridge spans two tracks of the CSX River Line, a heavily used freight rail corridor. The bridge was originally designed to span a single track with adequate horizontal and vertical clearances. However, CSX later realigned the tracks and introduced a siding, resulting in two tracks beneath the bridge and clearances that no longer met current standards.

The existing bridge structure also experienced significant deterioration. The prestressed concrete box beams, which serve as the bridge’s primary load-carrying elements, showed signs of deterioration, and cracking developed in the shear keys between beams. These conditions reduced the bridge’s load-carrying capacity and caused noticeable vibration when vehicles crossed the structure.

To address these deficiencies, the project replaces the bridge superstructure and upgrades nonstandard features while maintaining the existing substructure where feasible.

Snake Hill Road Bridge Before Replacement, image courtesy of the NYSDOT
Snake Hill Road Bridge Before Replacement

Engineering Scope

We provided comprehensive engineering and support services throughout the project, including:

  • Bridge inspection and condition evaluation
  • Topographic surveying and mapping
  • Environmental screening
  • Preliminary and final bridge design
  • Evaluation of bridge replacement alternatives
  • Work zone traffic control planning
  • Utility coordination
  • ROW incidentals and acquisition support
  • Cost estimating
  • Construction support and inspection services

Bridge Design Approach Over Railroad Tracks

Early in the project, our firm conducted a bridge study to evaluate potential replacement alternatives and determine the most effective design strategy. The selected solution replaced the superstructure while rehabilitating the existing substructure, improving structural performance and extending the bridge’s service life.

The final design incorporated several key improvements, including increased vertical clearance over the railroad to better accommodate current rail operations, updates to nonstandard bridge features to meet modern design criteria, and jointless construction to reduce long-term maintenance needs.

To minimize disruption to the community, the bridge replacement utilized Accelerated Bridge Construction (ABC) techniques, allowing the structure to be replaced within a single construction season.

Project Challenges

The project required careful coordination and engineering due to several constraints:

  • Active railroad corridor: Coordination with CSX Transportation was necessary to perform field inspections, surveys, and obtain clearance approvals.
  • Nonstandard clearances: The bridge design had to increase vertical clearance while remaining within the footprint of the existing structure.
  • Limited construction window: Accelerated construction methods were required to reduce the duration of the bridge closure.
  • Regulatory coordination: Approvals were required from both CSX Transportation and NYSDOT during design development.
Snake Hill Road Bridge crossing two CSX rail tracks in West Nyack, NY March 2024

Result - Accelerated Bridge Construction

The Snake Hill Road Bridge project delivered a modernized structure that meets current railroad clearance standards, restores full load capacity, and improves long-term reliability for the surrounding community. By combining targeted rehabilitation of the existing substructure with a new superstructure designed for accelerated construction, the project provides a cost-effective infrastructure upgrade with a 50-year service life.

We’re excited to share that McLaren Engineering Group is now part of KCI Technologies Inc., a 100% employee-owned firm offering engineering and consulting across all markets, and construction for communications and environmental projects.

Our commitment to excellence continues with the added strength of KCI’s full range of engineering and consulting services.

Visit KCI’s website to learn more.