“We love the fact that an all-precast solution can be built rapidly with a small work crew, … opening up a market to small contractors who may not have a large work force.”

Michael Culmo

 

Best Total Precast Concrete Bridge

Route 112 Bridge over the Kearney Brook in Worthington, Mass.

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The Route 112 Bridge over Kearney Brook in Worthington, Mass., is part of the state’s multi-billion-dollar, eight-year accelerated bridge program to fix bridges that have been deemed structurally deficient. It is also one of the first bridges in Massachusetts built with precast concrete abutments, though it surely won’t be the last.

“The goal of the project was to reduce road user impacts by reducing the construction time of the bridge,” says Michael Culmo, vice president of structures and transportation for CME Associates in East Hartford, Conn. By choosing an all–precast concrete solution, the designers were able to deliver a high-performance, cost-effective bridge in far less time than a traditional design.

In traditional bridge construction projects, the Massachusetts DOT would build the structure in stages over two years, Culmo says, but one of the goals of the accelerated bridge program is to accelerate construction so that all lanes of traffic are open before the winter shutdown. Designers were able to accelerate construction substantially by replacing the deteriorated single-span steel bridge with a more durable prestressed, precast concrete span that features a two-lane roadway curved with a radius of 920 ft (280 m).

“Precast concrete for all portions of the bridge is the tool that allows this approach to work,” Culmo says. “By prefabricating the elements off-site in a fabrication plant, the majority of the construction is completed before a shovel is placed in the ground, and construction was completed in 60 calendar days.”

Erection of the bridge could have been accomplished in even less time, Culmo says; however that would have led to cost increases. “The goal of this project was to build in a reasonably fast time frame, balancing construction speed with cost-effectiveness,” he says.

The only significant cast-in-place concrete on the project was the bridge deck topping. To simplify that process, the team used Northeast Extreme Tee (NEXT) beams as the deck forms, which meant that the contractor simply had to form the sides and ends of the deck. The NEXT beam was developed for the purpose of promoting greater uniformity among DOTs, engineers, and the precast concrete industry of the Northeast with respect to planning, designing, fabricating, and constructing highway bridges with the Federal Highway Administration’s philosophy of accelerated bridge construction.

During construction, the team placed the full 8 in. (200 mm) reinforced, high-performance concrete deck on top of the 4 in. (100 mm) thick top flange of the beam. “This technically results in a deck thickness of 12 in. (300 mm), which will provide a very durable, long-lasting structure,” Culmo says.

It’s also cost effective. “Preliminary investigations by several fabricators indicate that the NEXT beams could be as much as 40% less expensive than traditional beam slab bridges,” Culmo says. The savings is realized by simplifying the fabrication process, reducing the number of elements that need to be handled, and eliminating traditional deck forming. “The lack of forming and form stripping can offset the cost of additional concrete used in the deck.”

PHOTO CREDIT

CME Associates, Inc.

PROJECT CREDITS

Owner: Massachusetts Department of Transportation, Boston, Mass.
Engineer of Record: CME Associates Inc., East Hartford, Conn.
Precaster: William E. Dailey Precast LLC, Shaftsbury, Vt.
Precast Concrete Specialty Engineer: Calderwood Engineering, Richmond, Maine
Contractor: J. H. Maxymillian Inc., Pittsfield, Mass.
Total Cost: $900,000
Bridge Length: 64 ft. 6 in. (19.7 m)