"The public has gotten used to a very low-risk environment. And one of the reasons we live in a low-risk environment is because we put adequate resources into keeping things in good condition," he says. "This underscores the need not only to build new stuff -- which is what makes constituents happy with their politicians -- but to maintain our old stuff.
"I had a mentor professor at Cal who made a statement on the order of 'the true sign of an advanced civilization is not necessarily just what they build but how they maintain what they build,'" continued Ketchum. "We made wise investments in the 20s and 30s on the Golden Gate Bridge, Bay Bridge, dams, power plants and the like. These investments are reaching the ends of their design lives."
That doesn't mean they'll come crashing down the moment they reach the end of their anticipated life expectancies. But it does mean that significant investments may be in order to "maintain the integrity" of our aging transportation infrastructure, which was built generations ago.
"Those big bridges in Japan on the same scale of the Golden Gate and Bay Bridge have tolls several times higher than what we're paying here because they paid recent money to build them instead of old money," he notes. Our bridges "are paid off. We made wise investments and we've been reaping the benefits of them." But the time to pay appears to be here.
Incidentally, a generation or two down the road, engineers may not even know how to patch up decaying eyebars of the sort that plagued the Bay Bridge. Eyebars haven't been used in bridge design for at least 40 years and were outmoded more than 50 years ago (the 1958 Carquinez span, for example, didn't use them; the since-demolished '27 span did -- and was plagued by ruptures in the early 1970s).
Eyebars have given way to welded plate steel -- a stronger and more versatile system. For what it's worth: Eyebars can be used for tension -- pulling -- but not compression -- pushing. "So, near the pier on a cantilever bridge on the tower, you can use eyebars on the top but not on the bottom," explains Ketchum. Still confused? Okay, take a pen and hold it in front of you, horizontally, with one hand on either end. When you pull, that's tension. Push, and that's compression. When eyebars are forced to withstand compression, you get what engineers call "buckling," which leads to failure.
In any event Ketchum won't go out of his way to drive on the bridge -- again, he's a happy BART commuter -- but he won't avoid it either. "I think the risk is low enough that I'm there."