Inside the New Bay Bridge
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We started the tour on the new eastern skyway section of the bridge. Unlike the western span that connects San Francisco to Yerba Buena Island, the eastern span comprises two bridges: the skyway (the section closest to and connecting with Oakland) and the self-anchored suspension, or SAS, bridge (the section closet to Yerba Buena Island that will feature the new "signature tower"). Pictured here is the 15.5-foot pedestrian and bike path on the southern side of the eastbound lanes of the skyway.Photo by: Miyoko Ohtake -
The pedestrian and bike path features several outposts for viewing the bay (and for now, viewing the old Bay Bridge, originally completed in 1936). Though Caltrans and other authorities involved in the bridge building expect high volumes of foot and bicycle traffic, the path only connects West Oakland and Yerba Buena Island. Our tour guide, Ney, reported that the addition of a pedestrian and bike path on the western span is under consideration, though it's doubtful that it will become a reality due to costs and practicalities (Will Bay Area residents and visitors really want to traverse the eight-mile Bay Bridge by foot and bike?).Photo by: Miyoko Ohtake -
The new skyway stands in stark contrast to the old Bay Bridge but the two have been intensely linked together because one of the three requirements of the new Bay Bridge project was to keep one bridge open and functional throughout the duration of construction. The other requirements were for the bridge to be able to withstand the largest potential ground motions that could take place in a 1,500-year period (Caltrans is reluctant to give a Richter scale rating on the basis that it is a misrepresentation and miscalculation of bridge strength) and to have a standout, recognizable design. "The skyway's aesthetic is the bay itself," Ney says, "But the region wanted an iconic bridge as well, which is understandable since this is a bridge city with the Golden Gate known around the world."Photo by: Miyoko Ohtake -
Though Bay Area residents are used to the sight of the open, empty new highway, when the span are completed (with all hope) in 2013, it will be filled with the more than 280,00 vehicles that cross the bridge daily and make the Bay Bridge one of the three busiest bridges in the United States.Photo by: Miyoko Ohtake -
On tour, once we explored the top of the skyway, we headed into the bridge. Here, a view of the underside of the new spans.Photo by: Miyoko Ohtake -
As we headed up down the stairs into the bridge itself, we got a glimpse of the iconic Golden Gate bridge. Included in the legislature allowing the funding of the new bridge was a requirement that the new Bay Bridge include a "signature tower." The 525-foot tower, manufactured in China and completely erected there to test its strength before being dismantled and put on a ship, is currently en route to San Francisco and on-site construction is expected to begin in late July. The Warriors, the Bay Area's professional basketball team, recently unveiled its new logo and jersey featuring the yet-to-be-completed Bay Bridge tower. An old team logo featured a graphical representation of the Golden Gate Bridge.Photo by: Miyoko Ohtake -
When we went into the bridge, we first entered the electrical substation. The crane shown here is located above doors in the floor that open to lift equipment into the bridge from the bay below for repairs and maintenance.Photo by: Miyoko Ohtake -
Shown here, the inside of the new eastern span of the Bay Bridge. The acoustics in the concrete spans are incredibly poor and create loud echos so the bridge authorities are working with Skywalker Sound to dim the reverberations when work needs to be done in the tunnels.Photo by: Miyoko Ohtake -
Because concrete expands and contracts with changing temperatures (and the new Bay Bridge is expected to grow and shrink as much as six inches to two feet) and as a way to handle the tremors of an earthquake, a gap was built into the bridge with an expansion joint. Above, an accordionlike ceiling expands and compresses in response to movement. The tube shown here is a 60-foot-long, six-foot-wide, rolled-steel cylinder that slides between the two sides of the bridge. The swiggly chalk mark denotes the fuse section of the expansion joint. This is where most of the damage is predicted to be done when a big earthquake hits as the fuse, made of a softer material than the rest of the tube, will contort and deformed (though it is unlikely to break) as it absorbs and takes in the movement of the bridge. After an earthquake, the fuse can be cut out of the cylindrical expansion joint and replaced.Photo by: Miyoko Ohtake -
Next on our trip, we hopped on a boat for a water tour of the bridge. Pictured here is the transition from Yerba Buena Island and the beginning of the western end of the self-anchored suspension (SAS) bridge with the old Bay Bridge in the foreground.Photo by: Miyoko Ohtake -
After the new Bay Bridge (the lower of the two pictured) is completed, the old Bay Bridge will slowly be disassembled, likely beginning in 2014. The methodology for removing the parts (including trusses as long as 388 feet) will be up to the winning contractor. Most of the materials will be recycled and their sale costs will be incorporated into the bidding estimates. Parts of the bridge, however, will be preserved and kept in museums (perhaps including the planned Gateway Park at the eastern end of the bridge where construction headquarters are currently based) because the old Bay Bridge is listed on the National Register of Historic Places.Photo by: Miyoko Ohtake -
The SAS bridge is different from many bridge types in that the cables that hold up the spans are anchored in the bridge itself as opposed to footings at either end of the bridge or anchors along the way. Thus, in order to erect the structure, a false bridge (the brown structure shown here) had to be constructed. After the new Bay Bridge is completed, the false bridge will be dismantled.Photo by: Miyoko Ohtake -
Because of the costs, duration, and occasional disruptions to traffic of building the new bridge--as well as public interest in the project--the bridge authorities created baybridgeinfo.org and baybridge360.org to explain the process, show highlights, and post updates. They have also worked with Google to incorporate the new bridge into Google Earth by sending 3D frames and renderings to the company. As Google does not allow unbuilt projects to exist in Google Earth, the unbuilt section appear as translucent frames that are then made opaque as they are completed and the bridge authorities inform Google of the progress.Photo by: Miyoko Ohtake -
The eastern edge of Yerba Buena Island is where traffic will exit the tunnel through the island and travel onto the new bridge (shown on the right). What fascinated me was the small, boarded-up structure that is located at the base of the bridges and that sits quietly among the commotion.Photo by: Miyoko Ohtake -
Shown here is the base of the new tower, which will extend 525 feet into the air and act as a connection point for the cables.Photo by: Miyoko Ohtake -
From below, the pedestrian and bike path sticks out the southern side of the eastbound skyway and SAS bridge.Photo by: Miyoko Ohtake -
Because of the additional weight from the pedestrian and bike path on the southern side of the skyway and SAS bridge, counter balances (the small rectangles sticking out of the northern side of the bridge) had to be added to the spans.Photo by: Miyoko Ohtake -
The dark stripes across the bridge are the gaps between sections that make up the expansion joint and allow for the expansion and contraction of the concrete and absorb the movements of the bridge during an earthquake.Photo by: Miyoko Ohtake -
Because the old Bay Bridge is a nesting ground for cormorants, the design of the new bridge incorporates shelves off the underside of the smooth surfaces of the bridge so that the birds can build homes after the old Bay Bridge is torn down. Ney, our guide, jokingly referred to the ledges as the "cormorant condos."Photo by: Miyoko Ohtake -
The shape of the skyway mimics that of the SAS bridge, but it didn't have to. The SAS section required curved edges and angled sides to be more aerodynamic than the skyway, which has more anchors. The designers--T.Y. Lin International and --however, decided to carry the shape through the eastern skyway for a cohesive aesthetic.Photo by: Miyoko Ohtake -
Back on land, Ney showed off a piece of the main cable, made up of 17,000 wires and measuring over 36 inches. Seventy-five percent of the steel in the bridge is being fabricated in the United States, including that for the main cables, and the rest is coming from countries like China, Japan, and the United Kingdom. For more information and updates about the new Bay Bridge, visit baybridgeinfo.org and baybridge360.org.Photo by: Miyoko Ohtake
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