How to lift a 100-ton girder 1 inch: Up-close look at the Fauntleroy Expressway seismic-retrofit crewJanuary 13, 2012 at 10:31 pm | In Safety, Transportation, West Seattle news | 14 Comments
(Photos by Christopher Boffoli for WSB, unless otherwise credited)
Good news if you are among the nighttime drivers dealing with west-end bridge closures for the Fauntleroy Expressway quake-resistance project (well, technically, seismic retrofitting): The work is ahead of schedule, according to superintendent Jeff Bailey with general contractor C.A. Carey.
We (WSB editor Tracy Record and contributing photojournalist Christopher Boffoli) met Bailey and his crew last night while visiting the work site under the bridge with Bob Derry of Stepherson & Associates, which is doing communications consulting on the project; we’ve brought you their updates in multiple community-council reports over the past four months.
If you’re just tuning in – the Fauntleroy Expressway is the almost-half-century-old, half-mile-long western end of the high bridge. It’s undergoing work with this goal, from the project page: “Once completed, the seismic retrofitting improvements will decrease the probability that the Fauntleroy Expressway will collapse after a large magnitude earthquake.”
Seeing the current work up close, it’s not as dramatic as the images evoked when we heard the crew would spend months lifting the bridge deck, one section at a time, to replace rubber seismic cushions. The “lifting” does not involve some kind of big hoist, no cranes, nothing overhead, in fact – it actually involves crews going up in cherry-pickers to place a 600-pound jack under each (up to) 100-ton girder:
Here’s a closer look at one of the jacks:
Once the jacks are in place, the crew uses them to lift the bridge deck one inch (any more, Bailey explains, and the rules change), taking out the old cushion, then testing the space with this T-shaped tool dangling short chains:
(Cameraphone photo by Tracy Record)
The sound of the chain links against the concrete helps crews confirm if the concrete is in good shape.
(Photo courtesy Bob Derry)
And when they put in a new cushion, it has “glue” on one side. You can see all the phases in this video Christopher put together – including the traffic passing by on both sides of the work zone:
The project also has involved jacketing bridge support columns with steel. Next week, Bailey explained, they’ll put grout in, between the steel and the concrete, though he says the void isn’t that wide – one inch all around.
Watching all the work from beneath, we wondered aloud what’s visible atop the bridge while the deck is being raised from below. So Bailey took us up to look. Turns out you would barely notice the bump if you drove over it:
Our trip topside was more notable just for the chance to stand on the bridge without traffic.
(That’s Bailey at left, Derry at right.) But back underneath, the crew – about 20 people on an average night, according to Bailey – was moving forward, removing and replacing the cushions, one by one, moving from girder to girder, section to section.
So far, he added, they haven’t heard many complaints about effects of the project and its closures. We mentioned receiving a few notes earlier this week about the under-bridge park/ride spaces being blocked off earlier this week; he said the crews had moved fast enough in the previous few nights for much of the space to open back up again.
What’s next? Overnight closures are expected on weeknights the next two weeks; there’s no firm plan yet for weekend closures, which were mentioned as a possibility during community-meeting briefings next fall. The $3 million project, funded by the Bridging the Gap levy, is expected to be complete before summer.
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