Long Hill Brook Bridge
When Connecticut officials decided they needed to replace the deteriorated Long Hill Brook Bridge on Route 17 in Middletown, they knew the work needed to be completed quickly. The bridge was too critical for the heavy use it received to allow detours to last long. To achieve these goals, designers specified a precast concrete structure with ultra-high early strength so the bridge could be replaced over one weekend.
“With a lot of pre-planning, hard work by the project personnel, and support services along with good weather, Route 17 was able to reopen in time for morning commuter traffic and school buses at 6:15 a.m. Monday,” says DOT Commissioner James P. Redeker. In fact, the bridge reopened nine hours ahead of schedule. “Nine hours may not seem like a big deal, but to commuters, school kids, emergency services, and area residents, any time saved is a good thing.”
The existing concrete bridge, 16 feet long and 28 feet wide, had to be replaced due to its deterioration, according to a CONNDOT spokesperson. “The new bridge had to address the bridge’s structural deficiencies, functional obsolescence, hydraulic inadequacy, scour-critical rating, and substantial load rating.” Its narrow width also made it “functionally obsolete.”
The bridge features nine 29-foot-long precast concrete rigid-frame sections with a 7-foot rise and a 4’11-½-inch width. The structure also includes four bridge footings, four wingwalls, and four wingwall footings. It measures 31 feet long and supports a 41-foot-wide roadway with two 12-foot travel lanes with 8- to 9-foot shoulders. United Concrete Products fabricated the precast concrete components.
“We’ve used precast concrete on many projects but not on this rapid schedule,” says Mike Appleby, structural engineer with Anchor Engineering Services in Glastonbury, Connecticut, the design engineer on the project. “Precast concrete is our go-to method for rapid construction. It tends to be the most economical material for projects of this size and simplifies field work a lot.”
Significant pre-planning went into the project to ensure utilities were relocated and all sitework was completed so the components could be brought to the site and erected rapidly, he notes. The bridge was closed at 7 p.m. on a Friday, with the existing bridge then cut into pieces and lifted away to be demolished by contractor J. Iapaluccio Inc. Work continued until morning to excavate soil to bedrock. Then an ultra-high early-strength concrete was poured for a leveling pad. The concrete uses calcium sufoaluminate cement, which provided a two-hour strength of 3,000 psi.
Precast concrete footings were set onto the concrete pad, and the walls and frames were set into place. The bridge was ready for use by 6:15 a.m. Monday, ahead of the scheduled opening of 3 p.m. Finishing work then was completed over the next two weeks.
The project continues the state’s emphasis on using accelerated bridge construction (ABC) techniques, and it’s first one to replace an entire bridge, as an earlier one replaced only the superstructure, Appleby notes.
“Connecticut is definitely pushing to do more ABC projects. I expect that fabricating precast concrete components offsite and bringing them to the job for fast erection will become a standard and popular approach. We’d never used the ultra-high early-strength concrete, but I can see using it too for highly accelerated schedules in the future.”
Structural Precast Elements:
— Nine box culvert pieces 29 feet long and 44’ 10” wide.
— Four wingwalls with soil anchors, 8’1” tall.
— Four bridge footings.
— Four wingwall footings.
• Ultra-high early-strength concrete with CSA cement used for leveling pad to achieve two-hour strength of 3,000 psi.
• Bridge closed and reopened to public in 59 hours.