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Bay Bridge Tour - Pahavit's Universe

pahavit
Date: 3-23-2013 1:15 AM
Subject: Bay Bridge Tour
Security: Public
Tags:bay bridge, crane, field trip, hard hat, light, sign
Bay Bridge Tour


On Thursday D. and I attended a very special tour of the new Bay Bridge under construction in San Francisco Bay, and I took some pics.


First we begin with an orientation in the construction field office, where there are many models of the project to study.

Self-anchored suspension section model.



Yerba buena island transition structure model.



Cable section model.



Skyway info panel.



Self-anchored suspension info panel.



Yerba Buena island transition structure info panel.





After the orientation we head out to the boat that will take us over San Francisco Bay to the bridge.  At the dock we see the Left Coast Lifter, the largest barge crane ever used on the West Coast.





D. took this pic of the group of us in front of the crane before boarding the boat.



That crane is able to lift that big yellow thing behind us that says Versabar on it.  It weigh 1700 metric tons.



On board, we head toward the bridge.





We see San Francisco off the port bow, with the western span of the Bay Bridge visible.  This section of the bridge has already been seismically retrofitted and is not being rebuilt.





Life vests and hard hats were provided and required for the tour, because we are on a boat and it is an active construction zone.





The self-anchored suspension tower for the new bridge.





It has an elevator (orange box at lower right) and stairs.





They are welding above, tearing out the falsework that was holding up the new bridge until it could hold itself up.







More views of the tower.







The old span on the left, the new span on the right, converging at Yerba Buena Island.





There are signs on the bridge pillars.









The California Highway Patrol patrols the waters under the bridge to prevent pleasure boats from entering the construction zone.



I never expected to find Smokey on the Bay. 



Views of the falsework underneath the new bridge.







Underneath the new skyway section.





And more views of the tower.







The new cables make a rhythmic geometry in the sky.





Looking east toward Oakland, the skyway section makes an elegant swoop.









At the base of each of the new skyway pillars there is a maintenance door.  Their tiny size relative to each pillar shows the massive scale of the structure.





Looking west toward the convergence of the old and new structures.





The light standards for the new skyway are quite minimalist.









The expansion joint will allow some give to the overall bridge during the next big earthquake and prevent the entire structure from collapsing.





This is going to be a very beautiful bridge.





This section is where the old span broke during the 1989 Loma Prieta Earthquake.





When the broken section was fixed, the bridgeworkers had a troll fashioned from metal pieces left over from the repair.  Trolls guard bridges, and this one was installed on the repaired section to keep the span safe.



One assumes the new span will have its own troll made prior to opening.



Cormorants (Phalacrocorax auritus) love nesting on the old bridge structure.  Once it's torn down they will need a new place to roost and nest, and because they are a species of special concern, platforms were built under the new skyway section.  Circular grapevine nests have been placed on the platforms, as well as boxes and decoy birds to lure them there.  Speakers have also been installed to broadcast cormorant calls to make it seem more homey to them.











Another look west toward Yerba Buena Island before returning to port.





We see the Left Coast Lifter again as our boat pulls up at the dock.





Outside the field office we see a cross-section of the new bridge cable, full of wire.  It's made up of 17,000 wires and measuring over 36 inches across.



That's what's going to hold up the roadway for the 285,000 vehicles that cross the bridge every day.



We also see a 12-foot diameter tire from one of the special machines used to put the bridge together.







Read more in a Dwell article about it here.



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