RTD plans to make bridge move a spectator event

Crews will move light rail bridge to its place across 6th Avenue next month.

LAKEWOOD – When FasTracks rolls out the bridge that will span West 6th Avenue on the west side of the Federal Center, it will do so literally, closing down a stretch of the heavily traveled highway for two days.

And the Regional Transportation District plans to make the snail’s pace placement of the bridge a spectator event.

The huge span will be wheeled from its fabrication site south of the highway about 9 a.m. Saturday, April 24, and grandstands will be in place so the public can watch the slow-motion haul first-hand. The plans for the rollout are contained in a memo to RTD’s Board of Directors obtained by the Edge.

The transportation agency plans to make a major production of the move and will set up a public viewing area at the Office Liquidators lot on the north side of the 6th Avenue Frontage Road at Quail Street. The plans call for bleacher seating and the agency will distribute maps to the public about a week before the bridge starts its move.

The pace of the move will be anything but exciting, but is one of the first of it’s kind for the U.S. and one of only a few worldwide,  said Kevin Flynn, who publishes Inside Lane, an Internet site covering traffic issues and events in Colorado.

The design of the bridge, Flynn said, allow the bridge to be moved into place in one piece rather than built on-site.  The bridge will move about 25 feet per hour, a journey that will take an estimated 30 hours, according to RTD. It will be moved via two eight-axle, 35-foot transport platforms.

But the traffic impacts of the roll-out are no joking matter: All lanes of West 6th Avenue will shut down between Kipling Street and the Simms/Union exits for the entire weekend, from Friday evening until Monday morning, according to the memo. Major congestion can be expected along the detours – Kipling north to West Colfax Avenue then west to Simms and south back to West 6th for westbound traffic; and Union Boulevard south to West Alameda Avenue, then Kipling north to the highway for eastbound traffic.

Folks headed to or from the mountains and foothills can take Interstate 70 westbound to avoid the detours.

Despite the expected traffic tangles, RTD’ choice of bridge rollout dates is the best that could be expected, Flynn said.

“The closing of the freeway, I’m wondering how people are going to react to that,” Flynn said. “They (RTD) tried to pick a weekend that was ‘the least worst’ alternative for it,” Flynn said. “They chose the timing to come after the close of most of the ski resorts.”

The bridge was fabricated according to a timetable reached by working backward from that “least-worst’ choice of weekends, Flynn said.

The bridge “launch”, as the memo calls it, might be a slow haul, but the sight should be impressive. The bridge is 286 feet long, 43 feet wide and is 65 feet tall from crown to base. Its structural steel components weigh a total of 1.2 million pounds. The high-strength steel is “weathered”, turning brown as a “protective oxide coating” forms, eliminating the need for painting according to a fact sheet distributed with the FastTracks memo.

The bridge is a “clear span” design with no center pier in the freeway median to hold up the span. Instead 44 cables strung from the arch to the base provide support with an estimated breaking strength of 688,000 pounds. There are 1,950 feet of 23/8-inch cable criss-crossing the bridge.

The clear-span design will be wide enough from side pier to side pier to allow future widening of the freeway, the Simms-Union interchange ramps that pass beneath the bridge and the frontage road on the north side of West 6th Avenue.