7 September 2009

Bay Bridge Bypass

[Prefix: A huge, enormous thanks has to go out to Margena Wade, (Community Liaison Officer) and other staff at the Bay Bridge project at Caltrans for giving me the opportunity to go out and look at the construction of the bridge. It's an amazing project on an enormous scale, and I've been enormously lucky to have had the opportunity to go out and have a look at it first hand :)]

I set out on Friday afternoon after work to have a look at the Bay Bridge bypass construction work first hand. Heading over on the trusty 108 MUNI, I scuttled about Yerba Buena and Treasure Island trying to get a few good shots. I nabbed a spectacular moonrise over the construction site:

Bay Bridge bypass: Moonrise behind Bay Bridge

...as well as a time-lapse with ye olde plungercam of the old bridge section being rolled out, as well as a timelapse of the moonrise :)

However, I was lucky enough to be invited back to the island for a tour of the site on Saturday evening - and it was absolutely spectacular.

Bay bridge bypass: construction site

This is the boat pier on the East side of the bay bridge construction site. Here a service connected the two Caltrans command centres at Yerba Buena island, and it's from here I got the awesome ferry ride out on the water to have a look at the entire span of the bridge.

On the left hand side of the image you can see the new section of the bridge completely rolled into place; when I arrived on Saturday evening it was being worked on by engineering crews who were working on a pile of verification and connection tasks.

The bypass weighs about 7000 tons (!) and was assembled 50m up in the air and slid into place on rails. I asked about what it takes to overcome that sort of inertia to get it moving, and the answer was lots of hydraulics and dish soap.

In the mid-ground on the right two-thirds of the image, you can see the existing Bay bridge; just behind it is the new bridge. For the majority of the distance, the deck is in a side-by side configuration. I believe that the current point where it is up to is named W2; from there until pier E2 (mostly obscured by the construction work) it becomes a deck suspended by a pylon, and after that it converts into a double deck configuration to enter into Yerba Buena island.

Bay bridge bypass: E2 and W2

On the far left of the image, you can see 'falsework' construction leading up to pier E2; on the right, you can see the twin deck coming over from Oakland and pier W2. The falsework is in place so that the deck, which is normally going to be suspended from a pylon, can be constructed whilst the pylon is put into place. When the suspension cables are added, the falsework will be removed.

Bay bridge bypass: The Left Coast Lifter

The Left Coast Lifter is one of the world's largest floating cranes, and was constructed specifically for the job of installing sections of the Bay Bridge. This behemoth is about 30 stories high (!) and after the job with the Bay Bridge is likely to be deployed elsewhere. Before construction it was used to lift a sunken WW II tugboat. Here you can see it parked at Oakland, just in front of some falsework that is going to be used to temporarily support the span of the new bridge.

Bay bridge bypass: Plungercammed Oakland crane

One of the many characteristic cranes lining the Oakland foreshore.

Bay bridge bypass: Work on the cracked eyebar on the east span of the Bay Bridge

Inspection of the Bay Bridge revealed that a two-inch crack in an eyebar on the East span of the bridge; I'm pretty sure the crane and lift in the middle are near where the broken eyebar is. The crack means that the re-opening of the bridge may need to be delayed whist crews work overnight on fixing the problem.

Bay bridge bypass: East span of the Bay bridge with repair work on the broken eyebar

This is my favourite shot; the plungercam does all sorts of interesting things with smearing out point light sources. Golden hour at sunset is very, very kind to photographers in the Bay area summer :)

In the centre of the image you just make out the crane next to the newly discovered broken eyebar support on the bridge.

All in all, it was an awesome weekend :D The full photoset is here.

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