Oil Mill Road Bridges
Accelerated Bridge Construction (ABC) techniques were used to replace the deteriorated superstructures of two single-span bridges that carry Interstate Highway 95 over Oil Mill Road in Waterford, Connecticut. The project made use of hydraulic rollers to move the completed beam/slab assembly into place on tracks, the first such use of the technique in the state.
The bridge was constructed with NEXT beams, which were developed by the PCINE Bridge Technical Committee. They are double-tees but with wider stems that offer a more robust section, resulting in greater strength and shallower depths compared to other beam types. Bridge designers have found they provide an effective alternative to concrete box beams, offering better durability, faster construction, lower costs, and easier inspection.
The NEXT beams were chosen during the preliminary-engineering phase of the project, which evaluated rehabilitation options, including a superstructure-type study phase, explains Susan Bakulski, project engineer for CME Associates, a project-management consultant working for the DOT. “We compared a number of steel and concrete alternatives and chose NEXT beams because of their cost, constructability, and the capability to be fabricated off-site and delivered efficiently when needed, thereby reducing congestion.”
There was initial concern that concrete options would be too heavy for the existing abutments. It was later determined that the NEXT-beams loads were not substantial, and it was feasible to replace the superstructure and retain the substructure without concern. Each bridge consists of four 10’-4” wide NEXT 28F beams per span, with structure lengths of approximately 45 feet. Blakeslee Prestress fabricated all of the components.
The NEXT beams were fabricated while the general contractor, Brunalli Construction, constructed the approach spans and bridge seat-beam seats at the site. The new superstructure, comprising NEXT beams along with a cast-in-place concrete slab deck and parapet crash barriers, were built on temporary supports adjacent to the existing bridges. Then the existing superstructure was quickly demolished and the new spans were slid into place. Four slides were required, with one-half of each bridge installed within a 34-hour period.
“We looked at doing a more traditional lateral slide with a sliding surface and hydraulic jacks, but the contractor proposed to execute the slide with hydraulically driven self-propelled roller system These rollers have limited capacity, but the short span length resulted in loads that were within the capacities of the rollers,” Bakulski says.
The rollers also included internal hydraulic jacking mechanisms, which further facilitated the installation of the permanent bearings. A lateral-slide installation using NEXT beams was previously completed in Brewster, New York, but not in Connecticut, she adds.
The work moved smoothly, with additional concrete repairs and replacement to some substructure components included. Officials were pleased with the results, leading to several more projects being scheduled using NEXT beams, including a bridge in Stonington, Connecticut, scheduled for construction in the summer of 2017 and one in Preston, Connecticut, scheduled for construction in 2019.
Owner’s Project Manager:
Engineer of Record:
Heavy Lift Engineer:
• Bridges replaced by rolling superstructures into place.
• Superstructure beam lengths were 42’7” for southbound lanes and 42’11” for northbound lanes.