When the Colorado Department of Transportation needed to improve operations at Denver’s Pecos Street and Interstate 70 interchange, it chose an Accelerated Bridge Construction (ABC) approach to minimize interference with traffic flow. A replacement bridge was built near the site to be moved into place on tracked carriers as soon as the existing bridge was down. Demolition had to be done in a single night.
Everything had to be tightly choreographed to make it go as smoothly as possible. The plan was for Staker Parson Companies’ demolition crews to get the bridge down and out of the way by 7 a.m. Saturday morning. Since demolition couldn’t start until 11 p.m. Friday night, it meant the crews had just eight hours to get the job done.
An additional factor making demolition more difficult was that the bridge was in good shape. Donnie Fetters is owner and president of Performance Equipment of Erie, Colo., who supplied the equipment for the demolition. He said, “Demolition of a good bridge is about twice as hard. In the typical demolition project I see failures, places where rebar is exposed and cement is crumbling. Most structures we demolish practically want to come down. Not this one.” Yet, because it didn’t fit the new ramp scheme for I-70, it had to come down.
Fetters said, “We sent four hydraulic breakers and two CC 3300 Combi Cutters, all Atlas Copco.” Fetters, two technicians and two salesmen from Performance Equipment were on site during the overnight demolition project to make sure nothing slowed the crews down.
Demolition didn’t start right away. The tracked carriers for the new bridge needed a perfectly level surface to travel on, so the demolition crews were first tasked with spreading dirt to bear steel plates for the carriers. It was 3 a.m. by the time demolition actually started, leaving only four hours for completion.
“We attacked the bridge from both sides at the middle,” Fetters said, describing what he said was an ideal strategy. “Coming at that thing with six of those tools was just amazing.” A Combi Cutter was stationed at the center on both sides. Each was “nibbling away like on an ear of corn,” Fetters said. On either side of a Combi Cutter was a breaker.
Fetters explained how the combination of tools worked together. “The hammers can take a bridge down on their own, but they get hung up as rebar is exposed.” So every so often the Combi Cutter would reach over and shear through the rebar, freeing the breaker up. This accelerated the work of the hammer. Then the Combi Cutter would go help the other hammer out.
“The CC 3300s are good all-around cutters I can use in a variety of jobs, from taking down steel buildings to bridge demolition, like this one,” Fetters said. “And they’ve held up well. I’ve flipped the edges around, but you know what? They’re on a second set of knives, but I still haven’t had to change the teeth out. I have to compliment Atlas Copco on the equipment’s wear life.”