After a year of preparation, it took the team 90 days to plan the details of the bridge move. Demolition of the old bridge began on a Friday night in July, and at noon on Saturday, Netherlands-based heavy-cargo transportation specialist Mammoet started moving the 4.8-million-lb replacement bridge onto I-70. A series of grouped trailers worked like a hydraulic tripod to hold the bridge in "exactly the same plane" throughout the move, Paris says. "It was almost an automated procedure."

"But engineering involvement during the bridge move was critical because some of our original assumptions [about the move] were not valid," Hunter-Maurer says. "We had to shift some of the support points around."

Kiewit had more than 100 people working 2,500 man-hours around the clock to ensure the bridge was set safely. The move required 2,000 tons of imported dirt and 600 steel plates to line the travel pad. They ensured that the bridge stayed level and the freeway surface was not damaged by the massive trailers. The team monitored distortions and deflections closely during the move. The bridge was not physically attached to the trailers. "It was all just gravity," Paris says.

The new bridge had to be pivoted 180 degrees once it was on the freeway before it could be rolled into place in its final configuration around 1 a.m. on Sunday morning. The freeway opened on time for the Monday morning rush hour. The move went smoothly and safely, with minimal impacts, says Hunter-Maurer. The project was completed on schedule in the fall.

"We were blown away by the number of people who came out to the viewing area to see the move," says James Brady, Wilson & Co. senior vice president. "There was a real sense of pride in the neighborhood about the project."

The new bridge and Pecos Street interchange are a "night and day difference" from the previous alignments, Hunter-Maurer says.

EXTRAS:

Pedestrian HAWKs

When design on the project began, Remington School, located on the south side of the freeway, was up for sale. But as design progressed, Denver Public Schools decided instead to convert Remington to a charter school. That added another layer of complexity to the project: how to make the intersection safe for kids who would need to cross the interstate and the busy freeway ramps on their way to school.

The team opted to create a “pedestrian-safe travel path” through the area by placing a separate pedestrian bridge west of the vehicle bridge and adding special traffic signals at the ramps. The new HAWK, or High-Intensity Activated CrossWalK signals, use a pedestrian-activated, four-tier system—green, yellow, yellow, red. They give cars more time to slow down at pedestrian-busy cross streets but don’t create a long traffic queue in the roundabouts.

“It’s almost like a railroad crossing without the trains,” says Dave Paris, project manager with Kiewit.

It is CDOT’s first use of the new signals at a major interchange in the state.