Bridge repair seen as stopgap
By: John Upton and Mike Aldax
San Francisco Examiner
November 2, 2009
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| Open road: The Bay Bridge reopens Monday morning following a nearly weeklong closure to fix a damaged support beam. (Cindy Chew/The Examiner) |
SAN FRANCISCO — The Bay Bridge could be closed again in the coming months to allow Caltrans to replace a trouble-plagued repair to a cracked support beam.
The bridge reopened to traffic Monday morning after a historic near-weeklong closure. The span was closed Oct. 27 when steel components broke loose in strong wind gusts and fell onto traffic during the evening rush hour.
The recent repairs replaced and reinforced a failed fix of a support beam, called an eyebar, which had been completed during the scheduled Labor Day weekend closure. The latest work was characterized by Caltrans officials Monday as a short-term repair that will require exhaustive ongoing monitoring and maintenance.
On Sunday, Caltrans had been close to giving up on the repair and pursuing a new design after at least six exhaustive efforts to tense four tie rods failed to achieve 320,000 pounds of pressure.
“We’ve taken care of what we believe are the big issues that led to this failure,” said Rick Land, chief engineer for Caltrans.
According to Land, the tweaked fix will lessen vibrations better. But he offered no assurances that the fix could withstand an earthquake and he said no tests are available to predict the strength of wind gusts it could withstand.
“We spent a lot of time with three or four different sets of people going up and looking at the damper apparatus to see how we could move it around by hand,” Land said. “It’s pretty solid.”
He said the repair is a short-term fix and Caltrans will craft a permanent repair. That could use additional eyebars stacked on the cracked eyebar, or it could mean replacing the eyebar entirely, according to Land.
The short-term repair will be inspected daily for two weeks and a long-term repair could be ready within four months, he said.
It’s unclear how long the bridge will need to be closed for repairs, but Land said a scheduled shutdown could minimize traffic impacts.
Until Sunday, Caltrans resisted calls to redesign the failed repair. The design was hurriedly sketched on butcher paper during Labor Day weekend and the fabricated pieces failed to fit together properly until a heavy steel spacer was added.
“This does not reflect a flaw,” California Business, Transportation and Housing Agency Director Dale Bonner said Monday. “It’s the difference between what you look at in a laboratory in a controlled environment and what actually happens in real life conditions.”
-John Upton
Economy in good shape despite extended closure
The nearly weeklong Bay Bridge closure will likely have a minimal economic impact on businesses in The City, and industry leaders say they’re lucky it did not happen amid the holiday shopping season.
It was the longest bridge shutdown since the 1989 Loma Prieta earthquake, but the financial burden is expected to be nominal since “it’s a slow period of time in The City,” said Jim Lazarus, senior vice president of the San Francisco Chamber of Commerce.
“If this was the weeks before Christmas, where everyday counts for retailers ... you can’t replace that income stream,” he said.
Still, some businesses saw less foot traffic due to the closure.
“You’d find a lot of people who canceled [appointments in San Francisco], who worked from home or at a remote office,” Lazarus said.
Also, retailers were likely further pained because the closure extended into the weekend. And parking revenue likely dipped in The City as well, Lazarus said.
On the flipside, the bridge closure may have convinced some commuters to stay in The City after work to have dinner or stay in a hotel in an effort to avoid traffic, he said.
Angela Jackson, spokeswoman for the San Francisco Convention and Visitors Bureau, said the closure probably didn’t have a significant impact on tourism. Many visitors to The City arrive via San Francisco International Airport rather than the Bay Bridge, she said.
Jackson also said she didn’t think the weekend closure would have significantly deterred visitors from Halloween events.
— Mike Aldax
MTA: $1.9 million in toll revenue lost
The closure of the Bay Bridge for almost six days has resulted in a net loss of about $1.9 million in revenues on state-owned toll bridges in the Bay Area, Metropolitan Transportation Commission spokesman John Goodwin said Monday.
Goodwin said about $2.4 million in revenue from the Bay Bridge was lost. But he said part of that amount has been made up by increased traffic on other area bridges.
— Bay City News
Making the fix
The new repair design is intended to enhance the original fix installed during the Labor Day weekend scheduled closure. It incorporates three major upgrades:
- Significantly reduces vibration in the tie rods
- Engineers achieved this by developing a turnbuckle system that lashed the tie rods and eyebars together.
- Reduced potential for metal-on-metal contact
- Radiused nuts were used to secure the tie rods, which keeps them centered in their holes to minimize any metal-on-metal contact; protective sleeves were wrapped around the tie rods to prevent them from rubbing against the eyebars.
- Secured the repair system components
- Enhanced welds connect the crossbars to the saddles; tie rods are secured by a new anti-vibration system; saddles and tie rod ends are secured by tethering straps and cables.
Source: BayBridgeInfo.org
Our stories
“I telecommuted a couple days from southern Marin, mainly because I figured I’d alleviate some of the congestion on the roads. Generally, I have confidence in Caltrans engineers and the private engineers with whom they consult.”
-Jon Tomashoff, 52, Mill Valley
“I’m not confident in the crew. I don’t want to point fingers, but I feel like somebody is sleeping on the job.”
-Keenan Williams, 26, Oakland
“Every time I go on the Bay Bridge, I close my eyes and hope I don’t die.”
-Santiago Lerma, 28, The City
“It doesn’t make me nervous. You kind of take your life in your hands when you cross the street.”
Will Aspinwall, 26, The City
“I hope it’s safe. They said the wind caused the break, but shouldn’t they expect it to be windy on the bridge? It seems like they should have accounted for that.”
-Matt Moore, 25, The City
— Tamara Barak Aparton
