The removal, reconstruction, and widening of Interstate 25 north of Denver involved rebuilding and widening from four lanes to six. Lawson Construction Company, Longmont, Colo., rebuilt 7.5 miles and was responsible for final trimming of the grade and all of the concrete paving, from ramps to shoulders to the interstate paving.

“There were a lot of obstacles to this project,” Ken Lawson, president of Lawson Construction, said. “We had to work with traffic at all times and couldn't interfere with the flow on the interstate. The Colorado Department of Transportation (CDOT) put a lot of constraints on access and haul routes, and we had to do a lot of advanced planning on how we were going to deliver concrete to the project.”

At the very beginning of the paving process was grade preparation. Lawson used its Gomaco 9500 trimmer, sensoring off the paving stringline, to trim to the final depth. “We'd rather our dirt contractor over-fill the grade instead of under-filling,” Lawson explained.

Three different Gomaco pavers were at work on various sites across the project, slipforming shoulders, sometimes stringless. “Sometimes we just didn't have room for the stringline,” Lawson explained. “We just ran the paver on slope control and sensored off the new slab for grade control.”

Lawson paved 40.5-foot-wide strips while an in-the-pan dowel bar inserter (IDBI) inserted 36 bars, 1.5 inches (38 mm) in diameter, into the 13-inch-thick (330 mm) slab. “We love to slipform pavement as wide and as long as we can go,” Lawson said. “We poured 3140 cubic yards in eight hours on one pour, and we couldn't keep enough concrete in front of the paver.”