Bay Bridge bolts that haven't failed may be replaced

Bolt used on the new span of the Bay Bridge.
April 24, 2013 12:00:00 AM PDT
Caltrans now says they will need some time to determine how to retrofit a 2008 batch of bolts that failed on the new span of the Bay Bridge.

Besides retrofitting the bad batch of bolts from 2008, Caltrans will test another batch made in 2010 from the same manufacturer, the Ohio-based Dyson Corporation.

"Pending information that's going to come from tests that we're conducting on the 2010 bolts today, between now and then, we'll determine whether or not we can make the call on the 2010 bolts. It's the primary driver is whether or not we're going to make Labor Day or not," said Caltrans Director Malcolm Dougherty.

Meanwhile, Caltrans is deciding how to retrofit 96 giant bolts from 2008 that manage the sway of the bridge in an earthquake. One third of those broke when tensioned in March.

The bolts can't be removed because they are imbedded in concrete.

Engineers have come up with two options for reinforcing them with either a steel collar, or a steel saddle.

"The system that will be placed for the retrofit, like I said earlier, is going to be as good if not better than what was there," said Andre Boutros of the California Transportation Commission.

A memo shows that Caltrans went ahead and accepted the 2008 bolts even though a sample failed a crucial elongation test five years ago.

"That should have been red-flagged. They did not," said David Xu from Berkeley Engineering and Research, Inc.

"And the thing that really struck me is that when they did a test and it failed, even they overruled it, they mentioned that this is the third incident since November 2007," said Xu.

Caltrans claims to have learned from past mistakes.

"The susceptibility of these bolts was not identified in the testing protocols that we utilized before we installed them and we've developed a longer list of tests that we will subject future bolts to going forward," said Dougherty.

Caltrans dismissed initial estimates that the Bay Bridge bolt fix would cost just a million dollars, as premature. They hope to have a real estimate...and a final proposal for the retrofit of the original 2008 bolts by May 8.


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