Watching It Grow

For years now, I’ve had a front-row seat to one of the great construction projects of my lifetime: I have been able to watch close-up the construction of the new eastern span of the San Francisco-Oakland Bay Bridge.

As a sailing instructor, I have the opportunity to sail to Clipper Cove several times a month. This little body of water is located between Yerba Buena Island on the south and Treasure Island on the north. In some classes, we just anchor for lunch; for other classes, we spend the night anchored there. From this unique sea-level vantage point, the growth of the Bay Bridge’s new eastern span has been fascinating to observe.

First to appear were the mooring balls—a dozen or more of them, big steel things floating in the water between the bridge and the old Berkeley Pier. They were placed far enough east, in shallow water, to avoid interference with marine traffic using the channel between the mooring balls and Treasure Island. These mooring balls are used to secure the barges carrying the construction materials and to stage the various components of the bridge itself. Once the bridge is completed, they will be removed.

Next, work began on the foundations for the piers that will support the bridge. For a while, the work was mostly below the water and there wasn’t much to see. But soon the piers began to grow up out of the water and the progress was clear.

Then barges carrying giant molded concrete sculptures appeared. These sculptures were sections of the roadbed for the Skyway portion of the bridge, each slightly different from the others, yet all clearly of the same design. Once the piers were constructed, the sections were hoisted into place and secured to the piers. Slowly, one section at a time, the roadbed crept out from each side of each pier. Only after they met in the middle—and each arch was complete—could the temporary supporting materials be removed and the simple elegance of the design revealed.

The next pieces to appear were the steel deck sections that would make up the deck for the self-anchored suspension span or the SAS. So far 11 pairs of side-by-side deck sections have been installed, with two more to go. They are currently being held in place by temporary scaffolding until they can be suspended by the SAS cable and tower, which I could see being built around the same time. The tower that will support the single SAS cable consists of four separate legs, each able to move independently in the event of an earthquake, yet cross-braced to each other.

In mid April, a single steel cap (called the grillage) was added. This connects the four independent legs and will distribute the weight of the bridge onto all four legs. Another segment (called the saddle because of its shape), will soon be placed on top of the grillage. It will receive the cable. After installing the cable, a final piece, called the architectural head, will be added, bringing the total height of the tower to 525 feet (160 meters). Our SAS, with a length of 1542 feet (470 meters), is the largest example of this type of bridge construction in the world.

There is still a lot more to do before the planned opening in August or September 2013, but right now the project is ahead of schedule and it has been a pleasure to watch it grow!