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Rip Van Winkle Bridge Scour Susceptibility Study

| View Projects: Catskill, NY

  • Client:

    New York State Bridge Authority
  • Service:

    Highways & Other
  • Status:

  • Overview

    The catastrophic collapse of the Interstate 90 crossing of Schoharie Creek near Amsterdam, NY on April 5, 1987 was one of the most severe bridge failures in the United States. Ten people perished. The culprit?   Scour, it was concluded, was the cause of the collapse. Scour is defined as “the erosion or removal of streambed or bank material form bridge foundations due to flowing water”. It is the most common cause of highway bridge failures in the United States. Consequently, the FHWA has mandated that every bridge over water should be assessed as to its vulnerability to scour to determine what prudent measures are needed for that bridge.  The New York State Bridge Authority, tasked with safely and efficiently managing, maintaining and operating six major Hudson River crossings - handling over 58 million vehicles annually - acted upon the FHWA directive. They selected a trusted consultant, Modjeski and Masters, to investigate the possibility of scour at their Rip Van Winkle Bridge.
    Modjeski and Masters has been inspecting the Rip Van Winkle Bridge for decades. We are intimately familiar with its design and condition of its major structural components. Our scour vulnerability study commenced with the collection of existing field and design data. We then calculated the maximum scour depth using FHWA guidelines. This data helped us determine the stability of the bridge for incremental scour depths between the as-built ground elevation and the maximum-calculated scour depth and gave us the information we needed: the critical scour depth. The results of the study, along with our recommendations, were integrated into a comprehensive report that was delivered to the NYSBA.
    A relationship which began in the mid 1920s remains strong to this day. Within this time period, we have designed three of their major bridges:   the Mid-Hudson Bridge, in the 1920s; the Newburgh-Beacon Bridge, in the 1960s; and its twin, in the 1980s. We continue to provide engineering services which include bridge inspections, design of miscellaneous repairs, oversight of construction, and general input into the continued safe maintenance and operation of their facility. 
  • Description

    Tasks Performed
    • Scour Analysis

    Bridge Geometry
    • Length of Main Span – 800 feet
    • Total Project Length – 5,040 feet
    • Lanes on Structure - two lanes plus a pedestrian walkway
  • Testimonial

    “…As General Consultant to the New York State Bridge Authority for the last 30 years, your insight and effective investigations have greatly assisted us…” - William J. Moreau, Chief Engineer, New York State Bridge Authority
  • Credits

    Dr. Barney T. Martin, PE (Principal In Charge)
    Quentin P. Johnson, PE (Project Manager)