Hidden Tunnel Reveals Engineering Secrets Of The New Bay Bridge
SAN FRANCISCO (CBS) – The self-anchored suspension tower may be what makes the new Bay Bridge tower iconic, but a hidden aspect of the structure actually acts as the nerve center of the new eastern span.
Up a precarious flight of stairs, dangling over the bay is the entrance to a dimly-lit hall that most people will never see.
The hollow center of the new Bay Bridge is essentially a corridor that runs 1.7 miles from the middle of the bay all the way to Oakland, and along the way are several engineering marvels that make the new bridge safer than other spans.
"There's a lot of engineering that went into this bridge that people haven't seen and won't see," said Bay Bridge spokesman Andrew Gordon.
At the halfway point of the tunnel sits a maze of seismic fail-safes. If a major earthquake strikes, that section is filled with expansion joints that will move like accordions to absorb the force of the quake. A beam running through that section is also designed to contort and contain the seismic energy.
"If something is going to break, that's what's going to break," said Gordon.
That design means that crews will know quickly how to find and fix damage from an earthquake.
Also inside the tunnel are hatches that lead to additional arteries of the new span. Small openings lead to ladders that put engineers inside the concrete pillars that hold up the bridge.
"They're able to climb down inside the columns and take a look for any kind of the same cracks and fractures that may occur over time or after an earthquake," said Gordon.
Other features of the tunnel are a substation that powers the lights of the bridge as well as water and sewage lines that could act as a backup if Yerba Buena and Treasure Island lose water during an earthquake.
So while the new Bay Bridge may appear on the surface to have been built with style in mind, it was designed with functionality at its core.
The new span is scheduled to open over Labor Day weekend.
