RTD crews move fast on bridge’s slow rollout

FasTracks bridge moves slowly across West 6th Avenue Saturday morning.

LAKEWOOD – FasTrack’s light rail bridge was moving ahead of schedule Saturday, which could mean an early end the complete closure of a significant stretch of West 6th Avenue.

The bridge began its slow move about 2:30 a.m. Saturday and had cleared more than half the distance from its assembly site to its designated spot across the busy highway by 8:30 a.m. as dozens of spectators gathered to watch.

“We are making excellent progress,” said Jim Starling, RTD’s West Corridor Project Manager. “The bridge is 280 feet long and it has moved 149 feet.” Starling said shortly after crews delivered a progress report shortly after 8 a.m. “With the progress we are making, the closure should end earlier” than expected.

All lanes of the busy highway were closed between Kipling Street and the Simms/Union exits starting at 8 p.m. Friday, about 3 hours after partial lane closures began.

The stretch of highway affected by the rollout of the bridge originally was expected to remain closed until 5:30 a.m. Monday.

Once the bridge is in place across the highway, crews will take care of cleanup work and attaching the span to its abutment on the north side of 6th Avenue before the highway reopens, Starling said, crediting the project’s “excellent contractors” being well ahead of schedule by sunrise Saturday morning.

After snowy weather forced a postponement in last weekend’s original roll-out plan, FasTracks crews move earmarked this weekend for the rollout of the West Corridor light rail project’s signature double-track bridge across the busy highway just east of the Simms/Union interchange this weekend.

Construction crews have spent the past several months assembling the tied-arch, weathered steel bridge just south of and will move the span to its final position over the highway aboard a “dolly” made of two eight-axle, 35-foot platforms. The bridge traveled over guided rollers pushed by hydraulic rams capable of producing as much as 270,000 pounds of force per square inch.

The rollout, at speeds from 10 to 25 feet per hour, is expected to take up to 30

hours, according to RTD spokeswoman Brenda Tierney.

Although the move was far from a NASCAR-pace, on-lookers began showing up Friday night and some spent the night in nearby parking lots to make sure they had a good vantage point.

RTD installed bleacher seats for public viewing in a parking lot on the northeast corner of Quail Street and the 6th Avenue Frontage Road for Saturday’s crowd.

“That’s the only ‘formal’ day, the only day we will actually have bleachers out there and information and people from RTD there to answer questions. But we have leased the parking lot for the whole weekend. So if people want to drop by on Sunday and just stand there and look, that’s fine,” Tierney said.

The bridge is expected to reach it’s resting spot sometime between midnight Saturday and 6 a.m. Sunday morning.

“Sunday, they (crews) will spend cleaning up the highway and attaching the bridge to the other side,” Tierney said.

While spectators clearly were enthralled by the lumbering move, drivers probably will be grumbling throughout the weekend.

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 also can take Interstate 70 westbound to avoid the detours.

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.

It is one of only two or three clear-span bridges in the U.S. The design allowed it to be assembled, then moved into place instead of being put together in-place.

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 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.

If the bridge had been built in place over 6th Avenue, the project could have forced months of traffic nightmares.

“This approach to bridge construction enabled West Corridor crews to

work in a safe environment outside of traffic and significantly minimize impacts to commuters using the 6th Avenue freeway,” according to an RTD statement.

“If the bridge had been constructed in place over the highway, we would have had to impact traffic on 6th Avenue many times over the course of construction instead of just one weekend as we are doing,” Starling said “But safety is always the utmost priority.”

The 12.1-mile West Corridor light rail project is RTD’s first FasTracks project under construction. The line will link Union Station in downtown Denver with Lakewood, the Jeffco government complex in Golden and the Federal Center. It is expected to be in operation by 2013.