Bay Bridge breakdown caused by known flaw
By: John Upton and Tamara Barak Aparton
San Francisco Examiner
October 29, 2009
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| Empty toll lanes are seen on the Bay Bridge in Oakland Calif., Wednesday, Oct. 28, 2009. The San Francisco-Oakland Bay Bridge has been closed indefinitely after a rod installed during last month's emergency repairs snapped, causing a traffic nightmare for the 280,000 motorists who cross the landmark span every day. (AP) |
SAN FRANCISCO — Damage to the Bay Bridge that led to pieces of steel plummeting onto the roadway during rush hour Tuesday was known to officials, who neglected to make the repairs.
The bridge is now being fixed with many of the same pieces of failed equipment as well as the structural designs that led to an unexpected shutdown of the span.
Problems with the bridge began Labor Day weekend, when an inspection during a scheduled closure — for the building of a new self-anchored suspension bridge span — uncovered a rusted beam.
Caltrans, the agency that oversees the bridge, strengthened the surrounding area of the rusted beam, called an eyebar, with improvised steel components.
But the repair blueprints were hastily sketched on butcher paper by engineers working out in the field and were flawed. After steel repair components failed to fit properly, Caltrans used a massive steel box to hold the components in place.
As the components vibrated in strong winds during the past seven weeks, it led to a steel tie rod holding a brace in place to snap Tuesday.
That brace dragged a second tie rod onto the crowded roadway, according to Caltrans spokesman Bart Ney.
Wind-related vibration problems with a recent bridge repair had been identified last weekend, according to Ney. However, the problems were not deemed serious enough to prompt closure of the bridge, Ney added.
Caltrans on Wednesday was still designing enhancements for the repairs and would not say when the bridge would reopen, but the agency announced it was sticking by its basic original design.
Ney said Caltrans officials followed all protocols for repairing the eyebar and weekly maintenance inspections have taken place.
But he also said Caltrans failed to account for wind impacts when designing the repair.
“Wind is something that should have been accounted for. Something should have been done to dampen the vibrations,” Ney said. “There was a massive number of engineering projects going on.”
To better protect the repairs from strong winds, a strap will be wrapped around the repairs to reduce vibrations, according to Ney.
Additionally, shaking of tie rods that hold the repair in place will be reduced by nestling the nuts at the ends into newly scooped steel divots, he said. Other enhancements may also be developed.
Asked why Caltrans doesn’t redesign the flawed fix from scratch, Ney said that would lead to “tit-for-tat” disputes about the design.
“For something like this, simple is often the best,” he said. “We have our best minds working on it.”
UC Berkeley engineering professor Abdolhassan Astaneh-Asl said repair efforts should start from scratch.
“Caltrans should do it correctly,” he said. “It’s in complete violation of safety guidelines.”
-John Upton
Snarled commute likely for second day of closure
Saturated roadways and public transit — packed full of commuters diverted from the Bay Bridge closure — will likely continue today, as the span is expected to be shuttered for its second-straight morning.
The commute Wednesday morning nearly doubled for some drivers on clogged Bay Area freeways, and BART transbay ridership was up 50 percent from a typical Wednesday.
For as long as the Bay Bridge is closed, BART will continue to run longer trains during the start and end of the morning and evening commutes.
The transit service, however, will not be running overnight because Caltrans didn’t agree to reimburse the transit district and the maintenance crews for time needed to inspect the track for a busy Thursday.
Wednesday’s evening commute was also hampered by a power outage at the South Hayward station.
BART typically would carry about 55,800 passengers between the East Bay and San Francisco. On Wednesday, there were approximately 83,000 transbay riders.
Parking lots quickly filled to capacity, and BART officials are urging commuters to take the bus, walk or have someone drop them off at the stations this morning.
Those who did drive faced delays of an hour or two Wednesday that in some cases doubled commute times. The CHP reported double the number of cars on the road.
CHP Officer Scott Cakebread said motorists would likely encounter heavy congestion on the Richmond, San Mateo and Golden Gate bridges this morning.
-Tamara Barak Aparton
Wind helped bring down bridge part
Bay Bridge repairs were hampered by the same strong winds that caused steel parts to fall onto the roadway Tuesday.
Winds gusts Tuesday were a contributing factor in the failure of recently installed bridge components, but they were not necessarily the only factor, Caltrans spokesman Bart Ney said Wednesday.
Strong winds caused the steel repair components to vibrate, leading to metal fatigue, according to Ney.
The gusts interfered with repair efforts Wednesday because they created unsafe working conditions, he said.
“Wind has been a main concern for the crews,” Ney said.
Those winds are forecast to start dying down today, according to National Weather Service meteorologist Diane Henderson.
“The worst of it is over,” she said.
— John Upton
Saga of commuter chaos on the Bay Bridge
The piece that plunged from above the Bay Bridge on Tuesday was the same piece that workers scrambled to install during Labor Day weekend.
Thursday, Sept. 3 evening: Bridge shuts down over Labor Day weekend to allow work on replacement span
Saturday, Sept. 5 afternoon: Caltrans discovers dangerous crack in bridge on load-bearing eyebar
Sunday, Sept. 6 afternoon: Steel parts for eyebar repairs arrive at Bay Bridge from Arizona
Monday, Sept. 7 morning: Caltrans discovers the parts don’t fit together properly and orders an additional part as a makeshift solution
Monday, Sept. 7 evening: New part arrives at Bay Bridge from Oakland and is placed in position
Tuesday, Sept. 8 morning: Bay Bridge reopens several hours behind schedule
Tuesday, Oct. 27 afternoon: Several steel repair parts fall on peak hour traffic as wind causes bridge to vibrate
Tuesday, Oct. 27 evening: Caltrans closes bridge “indefinitely” for safety reasons and inspects damage
Wednesday, Oct. 28 morning: Caltrans announces fallen part will be put back in position and reinforced
— John Upton
Transit alternatives
Transit authorities are recommending that people avoid traveling across the Bay by working from home or taking the day off of work. If travel is necessary, here are some options (for the most up-to-date travel conditions, check www.511.org or call 511):
BART
The agency will be operating every available car and is calling in extra personnel to alleviate the commute crunch. Longer trains will also be running during non-commute times. BART warned riders not to park at its stations if they can avoid it, as parking lots will likely fill up quickly.
TREASURE ISLAND
The western span of the bridge will remain open for residents. Drivers must approach the Sterling Street onramp. Muni buses will still operate.
FERRIES
Several ferry operators will increase the amount of service during the closure.
AC TRANSIT
Routes that normally cross the Bay Bridge will run as usual, but instead terminate at BART stations.
DRIVING
The three main east-west bridges to be used as alternatives — Richmond-San Rafael, San Mateo and Dumbarton bridges — and the Golden Gate Bridge will likely experience heavier-than-normal traffic. The Golden Gate Bridge will have all toll booths staffed by 4 a.m.
Source: BART, Golden Gate Regional Transportation District, 511.org, www.baybridgeinfo.org
Gridlock
The unexpected closure of the Bay Bridge led to an increased number of passengers on BART and longer drive times for those who sought alternative routes.
139,000 Total BART passengers
83,000 Trans-bay BART passengers
55,800 Typical number of trans-bay BART passengers
395,300 (Sept. 4, 2008) Historic record for all-day BART ridership
50 percent Increase in BART trans-bay passengers
1-2 hours Morning commute by car from Oakland to The City
Sources: CHP, BART, 511.org
Examiner Staff Writers Will Reisman and Katie Worth contributed to this report.
