The new Bay Bridge eastern span has more than 1,200 bolts made from galvanized steel that is virtually identical to a high-strength alloy that a nationwide group of transportation officials banned for bridge use because it can crack over time, The Chronicle has learned.
The bolts serve vital roles on the new span: They anchor structures that are supposed to keep the bridge stable in an earthquake, they band the main cables together, hold the cables down at the top of the tower and bind them to the road decks.
Caltrans said last week that it was testing 192 bolts on the bridge that are similar to 32 galvanized rods that cracked when workers tightened them in March. Those failed bolts were made to be harder, Caltrans documents show, than the level at which federal guidelines consider them to be at risk of cracking when installed on a bridge — as were the 192 rods that the state is now testing for possible hidden dangers.
Caltrans documents examined by The Chronicle show that the state has procured 932 other fasteners for the bridge in the past five years that, like the failed bolts, were made of high-strength, galvanized steel.
The grade of steel used on the eastern span also ran contrary to guidelines laid out in Caltrans’ own bridge-construction manual, but Caltrans says that’s because the eastern span is an unusual project.
“Generic specifications are for a run-of-the-mill bridge, and this bridge is not run of the mill,’’ Caltrans Director Malcolm Dougherty said. “It is not unusual to follow project specific criteria.’’
For more on the warnings and potential dangers of the bolts, click here.