Contractor Shoots for Record Books on Colorado’s I-76 Job

Greg Scott is shooting for 832 batches of concrete in a single shift — a company record, if not a world record. “I don’t know of any other company that has done it,” he said. “I don’t know if anyone else has been crazy enough to try.” The company’s current record — 830 batches —was set last year.

Scott is project manager for Interstate Highway Constructors, the primary contractor on a 16-kilometer (10 mi.) stretch of Interstate 76 between Hudson and Keenesburg in eastern Colorado.

It’s not uncommon for Scott’s company to roll out 650 loads from its Rex model S, 12-yard dual drum batch plant. “It’s better than what most can do,” he said. When a job progresses smoothly, the company can do 58 to 60 loads an hour. The project manager conceded that such high production means starting early and quitting late.

Interstate Highway Constructors originated in Michigan more than 35 years ago and is now based in Englewood, CO. The company maintains crews in Michigan, as well as in Albuquerque, NM, and Denver, CO.

The three-phase, $28.6-million construction project, designed by Turner, Collie and Braden of Denver, takes a 40-year-old highway well past its prime and turns it into a safer transportation route for residents and travelers alike.

The project was originally scheduled for two and a half years, with work under way in the spring of 1999. Expectations now are that the job will be done by Nov. 1, 2000 — one year early and perhaps even under budget.

Scott said an earlier-than-usual start enabled the project to get the lead time it needed to be completed early. “We’re held to when we can have traffic head-to-head,” he said. In a normal year in Colorado, that’s April 1 to Nov. 1, since the heaviest snowfall is usually between November and March. “We prepared ourselves so we could get traffic switched early,” he added. And because of an unseasonably mild winter, Colorado Department of Transportation (CDOT) gave the go-ahead to start March 1.

Scott said the other key to keeping the project rolling has been the cooperation and honesty from all involved. “It’s a team effort. We have great partnering with CDOT and the subs.”

Glenn Frieler, project engineer for CDOT, said the first phase of the project included the installation of six new bridges, the rehabilitation of four bridges and modification of a large box culvert.

The trickiest of all was replacing the State Highway 52 bridge that crosses I-76. If the bridge was torn down in its entirety then replaced, residents of Keenesburg and Hudson and points between would have been cut off from the west side of I-76, and those on the west side would be cut off from the towns east of the highway. The solution? Ames Construction of Aurora, CO, replaced the bridge in halves, always keeping one half open to the public.

“It was like a Twinkie that you cut in half,” Frieler said. “And the cream filling did not fall out. The sub reinforced the cream filling.” In more technical terms, the contractor added support to the existing girder, then shifted the alignment two feet to cut the bridge in half in the correct spot. Crews used all kinds of demolition hammers mounted on a variety of track equipment.

Cranes and C Mag 43 diesel hammers, most often used on railroad bridges and trestles, were used to pound pilings. “It was a lot of intensive labor,” Frieler said.

It took four months — most of the winter — to replace the bridge. “It’s like building two structures and hooking them up in the middle,” Frieler explained.

When crews began replacing three smaller bridges along the frontage road, they discovered conditions fluctuated along with the irrigation schedule in this rural part of the state. When they were working in the Box Elder Creek bed, “We thought we were doing a good job dewatering, then everyone shut off their wells,” Frieler said. “We worked hard to dewater, then they turn their wells on.”

Two of the small local access bridges, however, required just minor rehabilitation. “As the interstate system was built, those were the first bridges and they’re in the best shape,” Frieler said. “The aggregate didn’t react with the cement like the others did. We stripped the asphalt off the top. We’re still happy with the way the structure looks.”

Along the highway, all of the culverts were extended and subcontractor Winslow Construction of Denver hauled in 380,000 cubic meters (500,000 cu. yds.) of dirt to fill in steep drop-offs that were too dangerous for today’s highway design standards. “We had 14 scrapers running at one time, along with dozers and graders,” Scott said.

Lights at the interchanges are being overhauled, too. DKS, also out of Denver, is replacing all lights and adding new ones at on and off ramps. Six miles of underground conduit and cable were trenched in to make the job possible.

The highway itself is getting a concrete overlay. The project calls for 400,000 square meters (480,000 sq. yds.) of new concrete, with an average depth of 244 millimeters (9.6 in.). Interstate is using a Gunner Zimmerman 1500 paver to spread the concrete 11.4 meters (37.5 ft.) wide. “We’re getting great ride results and excellent quality,” Scott said.

While paving is under way, traffic, much of it trucks, is head to head the entire 16-kilometer (10 mi.) stretch. The westbound lanes are under way now. When they are completed in mid-July, work will begin on the eastbound lanes with traffic detoured to the newly reconstructed westbound lanes.


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