UPDATE 4:52 p.m.:KQED and Bay City News – Metropolitan Transportation Commission officials said today that they’re troubled by the discovery of problems with 32 large bolts on the new eastern span of the Bay Bridge but they’re still hopeful the bridge will open on schedule in September.
Referring to other problems that have affected the lengthy construction process for building the new $6.4 billion span, MTC Executive Director Steve Heminger said, “We have surmounted far greater engineering challenges than this one and we’re confident that we’ll get through this one as well.”
Toll bridge program manager Tony Anziano told MTC board members at their meeting today that that 32 bolts ranging from 9 to 17 feet in length have popped out several inches since they were tightened several weeks ago.
Anziano said the rods went through quality control testing.
“They would have been tested at a laboratory on a sampling basis before they were installed,” Anziano said.
But Anziano says metal testing suggests hydrogen was present when the rods were manufactured, and that can make them brittle.
He gave no estimate on a cost or timeline for the repair. He said there’s no guarantee, but they’re still planning to open the bridge by Labor Day.
UPDATE: Caltrans officials discussed next steps for East Span construction this morning after discovering that one-third of the steel rods put under tension broke. Tony Anziano, the toll bridge program manager for Caltrans, explained that when the vertical rods snapped, it forced the bolts attached to the rods upward. There was no failure in the bolts themselves. The rods are part of the bridge’s seismic stability design and are not responsible for holding the weight of the bridge. They are meant to prevent the bridge’s deck from jolting upward and disconnecting from the massive pillars that support it in the event of a major earthquake.
The questionable rods were discovered on a pillar close to Treasure Island, but only 96 of the potentially 277 affected rods are accessible to work crews. Others are embedded in concrete. That means Caltrans won’t be able to replace all the rods and is considering other design options for seismic stability. One possibility is a collar to prevent upward movement of the deck.
Officials refused to discuss how much changing course would cost, but did say their budget includes room for setbacks like this one. They don’t expect it to delay completion of the project. KQED’s Rachel Dornhelm will be on a boat tour of the bridge construction this afternoon.
BAY CITY NEWS — Thirty-two large bolts on the new eastern span of the Bay Bridge have been discovered to be faulty, a Metropolitan Transportation Commission spokesman said this morning.
The bolts, ranging from 9 to 17 feet in length, are located near where the new span’s self-anchored suspension span meets its skyway, MTC spokesman John Goodwin said.
There are 288 anchoring bolts that tie the road decks down to a supporting pier below, and 32 have popped out a couple of inches since they were tightened, Goodwin said.
Over the course of the past month, the batch of bolts, which were manufacture
d in 2008, have failed to tighten properly due to excessive hydrogen in the steel, which causes embrittlement, he said.
“It’s not common, but it does happen,” Goodwin said, noting that the fault may have occurred during the manufacturing or galvanizing process in Ohio, where the bolts were made.
Based on preliminary estimates, the error might cost an extra $1 million to $5 million to correct because the giant bolts will need to be remanufactured specifically for the project, Goodwin said.
“We won’t be able to swing by Orchard Hardware,” he said.
The commissioners will get a full briefing on the situation at a meeting at 9:30 a.m. at 101 Eighth St. in Oakland.