At the moment, we have two bridges from Oakland to Yurba Buena Island as the new, self anchored suspension span Bay Bridge is being completed. We have the two bridges at the moment because Caltrans waited 23 years to replace a steel structure they said was unsafe. If were allowed to continue to use the existing bridge for 23 years, I suspect that the structure is safe and can be utilized for a less dynamic loading in the future. I propose that we not demolish the old bridge, but create a commercial development on both levels of the 1935 bridge similar to the Ponte Vecchio in Florence, Italy.
The original Ponte Vecchio, rebuilt after a flood in 1345, has survived WWII and many subsequent floods while providing a wonderful working, pedestrian/cycle bridge service. The shops on the bridge have housed some of the most sought-after gold and silversmiths in Italy and provides for a lovely and graceful promenade for Florentines to this day. It is an elegant, beautiful and useful link to each side of the Arno River. We could provide the same ‘over-the-water-experience’ with even better nautical views than in Florence.
On October 17, 1989, the 6.9 Loma Prieta earthquake rumbled through the bay area causing all kinds of damage on both sides of the bay. One of the most dramatic failures was on the eastern span of the Bay Bridge linking the East Bay communities with San Francisco.
Considering the age of the bridge, it suffered relatively little damage and is quite usable. The eastern, truss-cantilever section of the two-part Bay Bridge, anchored in the shallow bay mud, moved 7 inches to the east during the 10 to 15 seconds of the earthquake. The bridge connecting Oakland and Yurba Buena Island suffered a collapse of a 76-foot wide by 50-foot long section of the upper level roadway. The leading edge of this 50-foot section was resting on expansion slide plates and was designed to move horizontally up to 3 inches during seismic activity and normal expansion/contraction of the steel construction. This inadequate expansion joint condition has been corrected to conform to current thinking about earthquake movement. The foundations and rest of the steel trusses made it through with minor damage. This is surely a case for adaptive re-use rather than demolition.
I think we could save the cost of demolition of the existing steel bridge and convert it to a pedestrian, bicycle commercial event served by walking and bicycle paths and shuttles from the east and similar walkways from Yurba Buena at the west. The west approach will be supported by the future commercial/residential development of Yurba Buena Island being currently being planned by San Francisco.
