Accelerated Bridge Construction (ABC)

Lateral Slide

Siefert Associates, LLC successfully employed groundbreaking technology while engineering all aspects of this ABC project for Yonkers Contracting, reducing delays and traffic by 96% over traditional construction methods. The Eastbound and Westbound superstructures carrying Interstate I‐84 over Dingle Ridge Road in Brewster, NY were demolished and replaced over two separate weekend closures in the Fall of 2013. The innovative design involved building each new bridge adjacent to the existing bridge on a rail system supported on temporary bents. On the weekend of each closure, the existing bridge was demolished in‐place. The new bridge slid approximately 100 ft and the approaches raised approximately 2 ft to meet the new bridge elevation. Both bridges were completed and opened to traffic within 20 hours!

Other Slide Projects 

  • ​Hales Bridge over Metro North Railroad Westport, CT

  • I-95 over Oil Mill Road Waterford, CT


In June 2014, ABC using SPMTs became a reality in the State of Connecticut with the help of Northern Construction Service, Barnhart, and Siefert Associates. To transport payload weighing over 2‐million pounds and measuring 100 ft x 60 ft is a challenge. To transport that same payload when it sits 30 ft in the air and must be raised or lowered 4 ft while on the transporter, is unheard of.  Under the pressure of such a high‐profile project, on one of the State's busiest thoroughfares, the project team performed flawlessly.  Replacing not one, but two bridges of this magnitude in a single weekend is a huge credit to the project planning and execution, and especially to the investment in engineering hours that were put into solving the challenges of the SPMT arrangement.

Other SPMT Projects 

  • ​Morton St. Bridge Dorchester, MA

  • River St. Bridge Hyde Park, MA

  • Route 2 overpass Phillipston, MA

  • Clayton Street Bridge Dorchester, MA

  • I-95 over Oil Mill Road Waterford, CT

Precast/Prefab Element Projects 

  • CT Fast Track Busway New Britain/Hartford Hartford, CT

  • Brooklyn Bridge Manhattan, NY

  • Patroon Island Bridge Albany, NY

  • MNRR over Fairfield Ave Fairfield, CT

  • Tappan Zee Bridge Re-decking Rockland/Westchester, NY

  • Pulaski Skyway New Jersey