COURTESY OF SARGENT CORPORATION
The Thomas Brook Rail Bridge Replacement in Oakfield, Maine, was built beneath an active railyard where schedule, access, and safety all carried real consequences. The existing crossing was a failing concrete box culvert. The replacement is a 170-foot precast concrete arch installed beneath six rail tracks, staged so the vital rail operations between the U.S. and Canada could return quickly once the structure was in place.
As the night crew superintendent, Jonathan Nadeau, put it, “Oakfield was one of the most time-demanding projects I’ve worked on during my nearly 20-year career. It took a lot of people doing a lot of the right things.”
A schedule-critical part of the work was the closure pours, the connection points that tie the precast system together and allow backfill to move forward. Those pours set the pace for the sequence because the work could not progress until the concrete reached 4,000 psi. “The concrete had to cure within 12 hours maximum in order for backfill,” Project Executive Brent Williams explained.
That requirement shaped the entire approach in the field, including the materials used and their placement. “The problem with this quick-curing mix is that you pour it in, and as soon as that water hits it, it just sets. So you’ve got about one minute, and it’s ready to go,” Williams said. To maintain control of the mix and ensure the process is repeatable, the team adapted the placement method. Williams continued, “We used a variable-speed conveyor to feed the hopper at the pace we needed, added water by hand, and had everything premeasured. I couldn’t believe how well it worked.”
The rest of the project had to be built around that same level of constraint. “We had 14 days to remove the tracks, and a 96-hour window to complete the main line. We completed the first phase as one crew, so when we shifted to 24-hour operations with separate day and night teams, everyone had already seen the full process, regardless of which step we were on,” Superintendent Keith Edgecomb explained. “In the end, we completed in 83 hours, 13 hours ahead of schedule.”
Around-the-clock work can add risk if it is not structured. The crew treated safety as part of the plan, not a secondary task. “It was not a race. We had 7,600 man-hours with no safety incidents,” Edgecomb said.
Engineering News-Record (ENR) is a long-running construction industry publication that covers projects, markets, and performance nationwide. ENR’s Best Projects program starts with regional competitions, where ENR notes that more than 800 project teams entered, and more than 200 regional winners advanced to the national round. From that pool, ENR selects 20 Best of the Best Projects winners. Thomas Brook was first recognized at the ENR New England Best Projects awards ceremony in Boston on December 11, 2025, and was later selected as a national ENR Best of the Best Projects winner in the Small Project category. Members of the Sargent field crew will attend the national awards event in New York City on March 26, 2026.
For more Sargent stories, visit www.sargent.us and listen to the “Sargent: On Track Podcast” on iTunes and Spotify.