Photo by Sebastian Bennage, courtesy of Sargent Corp.

Rather than doing most work during the shutdown, the team increased early phase activity to rehearse installation methods and confirm tolerances before the rail closure. While shifting more work into the critical window, the method allowed crews to work at full efficiency during the rail operations stoppage. Operating continuously during the outage, crews coordinated excavation, foundation preparation and placement of a 170-ft precast arch culvert system. A total of 67 precast concrete elements—fabricated offsite—were delivered and installed with sub-inch accuracy. Digital survey control and pre-pour dimensional checks ensured each piece fit as intended, eliminating field adjustments. Concrete had to cure within 12 hours, said Brent Williams, Sargent project executive. “You pour it in, and as soon as that water hits it, it just sets,” he said. “You’ve got about one minute, and it’s ready to go.”

The schedule was almost disrupted when rapid-strength concrete needed for closure pours wasn’t available days before use. Because the pours had to reach 5,000-psi strength within hours to allow backfilling and track restoration, the team quickly evaluated alternative mixes, verified performance through testing and secured specialized skid-steer mixers to prevent premature setting to avoid idle time during the shutdown.