Just when we thought we could stop holding our breath every time we cruise over the scenic new Bay Bridge, a pair of new reports indicate key pieces of the eastern span, which isn't even a year old at this point, could start falling apart well ahead of its intended 150-year lifespan.
First up, an investigation by Sacramento Bee has found that the single suspension cable is showing an alarming amount of rust inside two sealed chambers located beneath the east and westbound road decks where the cable attaches to anchor rods. According to a top Caltrans engineer the two chambers were "drenched for about a year between December 2011 and December 2012 during construction" even though they were meant to be water-tight and dehumidified to prevent such corrosion. Making things worse, 2012 saw some 21 inches of rainfall (not to mention the notoriously wet and foggy conditions over the Bay), and the chambers have continued to spring leaks despite efforts by Caltrans to keep them dry.
According to UC Berkeley engineering professor and steel bridge expert Abolhassan Astaneh-Asl, this is a very bad thing: “The implications are structural - and very serious,” Astaneh told the Bee. “This bridge is fracture critical, which means if any important element of this bridge fails ... the bridge is going to collapse.” Bridge spokesman Andrew Gordon, on the other hand, denied there was any cause for alarm saying the rust was merely a byproduct of metal shavings left behind by construction work and that Caltrans was "still buttoning up the bridge" and they hope to seal the leaks before the next rainy season.
Meanwhile, elsewhere on the bridge: the Chronicle has spotted some ill-fitting joints and shoddy welds that could easily crack as more and more traffic pounds its way across the bridge. The paper alleges Caltrans allowed the bridge builders to weld together separate Chinese-built sections of the road deck even though they did not quite fit together as snugly as their own rules prescribed.
Although a crack in these joints would not cause the bridge to fall into the bay right away, it would mean the already over-budget bridge will be due for repairs much earlier than expected and, in general, makes the brand new bridge a less-than-ideal exit route in the event of a earthquake. In this case, Caltrans again tried to rationalize the lax regulations by saying they went with a looser national standard.