Tag Archives: San Francisco

Golden Gate celebrates 75th with help of engineers

The Golden Gate Bridge was heralded as an engineering marvel when it opened in 1937. It was the world’s longest suspension span and had been built across a strait that critics said was too treacherous to be bridged.

But as the iconic span approaches its 75th anniversary over Memorial Day weekend, the generations of engineers who have overseen it all these years say keeping it up and open has been something of a marvel unto itself.

Crews had to install a bracing system after high winds lashed and twisted the span in the 1950s, raising fears it would collapse. Years later, they had to replace vertical cables when they were found to have corroded in the bridge’s damp, foggy climate, potentially destabilizing the span.

The bridge, which rises majestically above a Civil War era fort on the San Francisco side and arches across to the Marin County headlands on the north side, is currently in the midst of a seismic upgrade that has seen many of its key structures replaced or modified. Plans for a moveable barrier to separate north and southbound traffic and a net system to prevent suicides are also moving forward.

“When (one of the bridge’s designers) made his final speech during opening day ceremonies in 1937, he said, ‘I present to you a bridge that will last forever,'” said Daniel Mohn, the bridge’s former chief engineer, who co-authored a book about the span. “What he should have said is, ‘I present to you a bridge that will last forever if properly maintained.'”

The idea for a bridge across the Golden Gate strait, where San Francisco Bay meets the Pacific Ocean, was championed by the engineer Joseph Strauss in the 1920s. Strauss’s original design, submitted to San Francisco city officials in 1921, called for a hybrid cantilever-suspension bridge. The idea for a full-suspension span — the design that was ultimately built — came later.

At a little more than three-fourths of a mile in length, the Golden Gate Bridge would become the world’s longest suspension span.

It had to be light enough to hang from its own cables, but still strong enough to withstand the strait’s fierce winds and the possibility of earthquakes. Some said it was impossible.

Engineers also had to calculate all the potential forces on the bridge without the help of computers.

“In those days, you had (notebooks) and a number two pencil and you wrote it out, did all the math at your desk,” said Kevin Starr, a history professor at the University of Southern California, who has also written about the bridge.

Eleven men died during construction from 1933 to 1937 — ten of them when scaffolding fell through a safety net that had been set up to protect workers.

The conditions were difficult, cold, foggy and windy, and workers who helped construct supports for the south tower had to contend with dangerous tides.

But it was the wind that would continue to vex engineers years after the bridge’s completion. In 1951, it was closed for several hours when wind gusts approached 70 mph and caused the bridge to flutter.

It was twisting so badly, Mohn recalled during a recent phone interview, that the light standards at the center of the span were striking the main cables.

“It sure almost destroyed the Golden Gate Bridge,” he said. The Tacoma Narrows Bridge in Washington — a suspension bridge whose designer also worked on the Golden Gate — had twisted and snapped in about 40 mph winds a little more than a decade earlier. That 1940 collapse was captured on film.

Although the Golden Gate Bridge had stiffening trusses that made it less susceptible to wind, it did sustain damage, Mohn said.

Officials decided to add lateral bracing that made the trusses more stable and reduced the chances of the bridge going into a potentially catastrophic twisting motion.

The bridge would be able to withstand winds of 70 mph today although the goal is to eventually increase its tolerance to 100 mph, according to Ewa Bauer, the bridge’s current chief engineer.

The wind is not the only element to take its toll on the span. The damp, foggy air has also kept its painters and engineers busy.

“You couldn’t have put the bridge in a more corrosive atmosphere than in the middle of the Golden Gate with that salt fog coming in,” Mohn said.

Engineers discovered in the 1970s that the bridge’s suspender ropes — the vertical cables that connect the deck to the main cables — had corroded, some so badly that they could be picked apart with a pocket knife.

The problem in part, Mohn said, was that bridge maintenance had been neglected for many years, particularly during World War II. A design flaw also hastened corrosion.

All of the cables were replaced in the mid-1970s.

There was another scare on the bridge during its 50th anniversary in 1987 when an estimated 300,000 pedestrians gathered on the span, which was closed to vehicle traffic.

The weight of the crowd flattened out the arch of the bridge deck and caused some revelers to suffer motion sickness as the bridge swayed.

Although the bridge supported its heaviest load in 50 years that day, Mohn would later conclude the weight and movement had not exceeded its design capacity.

Today, among the engineers’ most pressing concerns is the potential effect of a major earthquake.

The 1989 Loma Prieta earthquake, which occurred during a live broadcast of the World Series, caused two 50-foot sections of the San Francisco-Oakland Bay Bridge to collapse.

The Golden Gate Bridge was not damaged. But the quake still spurred bridge officials to undertake a massive retrofit of the span — a $660 million project that began in 1997 and is still underway.

Bridge pylons have been reinforced with steel and towers under the bridge’s two approaches were replaced, all while keeping the bridge open and its appearance unchanged. Retrofitting the suspension span is the project’s final phase although experts say its flexibility makes it less vulnerable in an earthquake.

“If I knew when an earthquake was coming, I’d get to the suspension span of the Bay Bridge or the Golden Gate Bridge,” said Abolhassan Astaneh-Asl, an engineering professor at the University of California, Berkeley who studied the Golden Gate Bridge after Loma Prieta. “They are safest places to be.”

The goal is to withstand an 8.1-magnitude earthquake when the retrofit is completed years from now.

The bridge district is also moving forward with plans for a steel net below the span to prevent suicides.

The Golden Gate Bridge has long lured people looking to end their lives. More than 1,200 people have plunged to their deaths from the span since it opened.

The bridge’s board of directors approved the net system in 2008. Funding for the project, which is estimated to cost tens of millions of dollars, has not yet been secured but work on its final design is underway.

The bridge, like other infrastructure, has a lifespan. But Bauer and Mohn say with proper maintenance, the Golden Gate Bridge will endure. The retrofit project alone will buy the span another 150 years, Bauer estimated.

“I believe the bridge was built to absolute great standards of workmanship,” she said on a recent morning at a vista point overlooking the span. “What we are doing right now is repairing…and you can truly do it indefinitely.”
SOURCE: http://www.foxnews.com/us/2012/05/21/golden-gate-celebrates-75th-with-help-engineers/#ixzz1vbw4i0C0

City of San Francisco sues to force feds to improve pipeline safety

The city of San Francisco took the unusual step Tuesday of asking a judge to force federal natural-gas safety regulators to step up efforts in California, saying the government “abjectly failed” to enforce pipeline laws before and after the 2010 explosion that devastated a San Bruno neighborhood.

At issue in City Attorney Dennis Herrera’s lawsuit, filed in U.S. District Court in San Francisco, is the performance of the little-known U.S. Pipeline and Hazardous Materials Safety Administration. Although it is charged with enforcing federal safety law, the agency relies on states to do much of its oversight.

Herrera’s suit says federal officials never set standards and let California’s enforcement dwindle in the years leading up to the September 2010 explosion of a PG&E pipeline in San Bruno.

‘Blind trust in operators’

In its investigative report on the blast, which killed eight people and destroyed 38 homes, the National Transportation Safety Board recommended that the pipeline agency tighten regulations on operators. The board’s chairwoman, Deborah Hersman, said PG&E had “exploited weaknesses in a lax system of oversight, and regulatory agencies that placed a blind trust in operators to the detriment of public safety.”

Herrera’s lawsuit echoes those findings, saying the pipeline agency stood by for more than a decade while the California Public Utilities Commission failed to detect PG&E’s safety problems, questionable pipeline-management practices and shoddy record keeping.

The state agency allowed utilities to police and report their own safety violations in lieu of being fined. The agency has changed its approach since the San Bruno disaster and recently proposed a $16.8 million penalty against PG&E for failing to conduct leak inspections on several miles of gas distribution pipelines in the East Bay.

“In the absence of any meaningful oversight by PHMSA, the CPUC has, for decades, forsaken its duty to enforce federal pipeline safety standards,” the city said in its suit. Under those circumstances, the suit said, “it is not a question of if another pipeline will explode, but a question of when.”

The pipeline safety agency issued a statement Tuesday declining to comment on the lawsuit but stressing its “core” commitment to safety.

“That’s why we devoted hundreds of hours of staff support and technical expertise to the NTSB and the California Public Utilities Commission to understand the San Bruno tragedy,” the agency said.

Failure to monitor

The suit said the federal government’s failures were putting San Franciscans at risk. It is the first time a local government has sought stricter regulation from the pipeline safety agency, said Rick Kessler, a lobbyist for the Pipeline Safety Trust, a nonprofit that focuses on safety improvements.

“If this brings better oversight and enforcement,” he said, “I applaud it.”

The suit seeks a court order to compel federal pipeline safety officials to set performance standards for state regulators who oversee gas transmission lines.

According to the complaint, the U.S. pipeline agency gave California $1.3 million in 2010 to oversee pipeline safety, yet “never meaningfully evaluated” how the money was spent or measured the effectiveness of the state’s program.

Federal officials knew California’s enforcement efforts had been understaffed since 1998, the suit said, resulting in a small proportion of federal funding being allocated to the state. Inspections became so infrequent by 2006 that the pipeline agency warned the Public Utilities Commission that California was jeopardizing public safety.

The explosion of a gas distribution pipeline in Cupertino in August, in which a condominium was destroyed, is evidence that the federal government hasn’t done enough to strengthen its regulatory efforts since the San Bruno disaster, the suit said.

That explosion happened because of a leak in a notoriously brittle type of 1970s-era plastic pipe, which the government recommended in 1998 that pipeline operators replace. Regulators have never ordered companies to do so, though.

Giving up authority

The federal agency, “for all practical purposes, has allowed gas pipeline operators like PG&E to regulate themselves and, in doing so, has improperly delegated its authority to enforce federal pipeline safety standards to those operators,” the suit said.

Although Herrera earlier threatened to sue the Public Utilities Commission as well, he said Tuesday that the state agency has improved its oversight of PG&E since 2010.

“We are participating in the administrative process to make sure the CPUC follows through on its pledge,” Herrera said in an interview.

PG&E had no comment on the suit except to emphasize actions it has taken since the San Bruno explosion to try to make its gas system safer.

SOURCE: http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2012/02/14/MNKU1N7J3D.DTL#ixzz1mZJosbrD

PG&E replacing plastic pipes in Cupertino

A San Francisco  neighborhood is being made safer.

PG&E is replacing thousands of feet of dangerous plastic pipeline that carries natural gas. That kind of pipe has a history of failure and it did so recently in the very spot where PG&E is now changing it out.

PG&E crews began carving out sections of the street to gain access to the old plastic pipeline.

“The lines you see here along the road and outside the homes, those are the main lines and from the main line and from there branching out to the individual service lines that go directly to the meter,” PG&E spokesperson Brian Swanson said.

Twelve-thousand feet of pipeline will be replaced after a gas leak caused an explosion that rocked a Cupertino neighborhood on August 31.

The type of plastic used in Cupertino has failed in the past. The maker, had warned pipe made prior to 1973 can crack.

Assm. Jerry Hill, D-San Mateo, says there were other warnings.

“The National Transportation Safety Board in 1998 came out with a recommendation that the pipes should be checked, monitored and replaced; here again nobody did anything about it,” Hill said.

PG&&E claims it has.

Still, the utility company says replacing all plastic pre-1973 pipes was not priority until now.

PG&E will replace 1,200 miles of the plastic pipeline system wide, which will take at least four years.

Hill will now introduce legislation demanding that all safety recommendation made by the National Transportation Safety Board be adopted by all utility companies.

SOURCE: http://abclocal.go.com/kgo/story?section=news/local/south_bay&id=8424072

GOP pipeline bill would block pipeline safety reforms

Professionals who work safely, diligently, and follow US government regulations  in the Natural Gas, Oil, Pipeline, Corrosion or Cathodic Protection area of expertise are reminded that Friday, Sept 9, 2011 is the one year anniversary when a catastrophic Natural Gas pipeline disaster occurred in San Bruno, California.  

The accident destroyed 38 homes, damaged 70 killed 8 people and injured 58 others.

But, on Wednesday of this week a pipeline bill offered by House Republicans would block some safety reforms and ignores other recent safety recommendations made by accident investigators in response to the deadly gas explosion.

The bill would prohibit federal regulators from requiring pipeline operators to inspect the structural integrity of major transmission lines in lightly populated areas. It would also bar regulators from setting standards for industry on detecting leaks. Instead, it tells regulators to study both issues and come back with findings in a year or two.

After a series of gas and oil pipeline accidents over the past year, the Department of Transportation recently said it was considering whether to require operators to examine the integrity of major pipelines everywhere, not just in densely populated areas as is currently required.

The bill was posted online Wednesday by the House Transportation and Infrastructure Committee. The committee is tentatively scheduled to vote on it on Thursday.

The bill “improves safety, enhances reliability, and provides regulatory certainty that will help create new jobs,” Rep. Bill Shuster, R-Pa., the bill’s chief sponsor, said in a statement.

But safety advocates said the bill would undermine safety, and the nation’s top accident investigator cautioned against blocking regulators from imposing tougher standards on industry.

“As a result of the investigation in San Bruno and others across the country, the NTSB would be concerned about any legislation that weakens an already lax system of oversight,” board chairman Deborah Hersman said in a statement.

The board is also investigating gas pipeline explosions in Philadelphia and Allentown, Pa., and an oil pipeline spills that fouled the Kalamazoo River near Marshall, Mich.

The GOP bill is silent on several key NTSB recommendations, including that gas companies be required to install automatic shutoff valves on transmission lines in densely populated areas. The pipeline that ruptured underneath a San Bruno subdivision ignited a pillar of fire that flared like a giant blowtorch for more than 90 minutes before gas company employees could manually close valves, shutting off gas to the line.

PG&E has estimated the cost of replacing or retrofitting its current 300 manual values with automatic valves at $100,000 to $1.5 million per valve, depending on the difficulty of the installation. Federal regulators have also said they are considering requiring operators to install more automatic valves.

Another NTSB recommendation not in the bill is that all gas transmission pipelines constructed before 1970 be subjected to a hydrostatic pressure test that incorporates a spike test. Pipelines constructed before 1970, like the one in San Bruno, are exempted from the testing requirements.

“It’s surprising that right after NTSB did one of their largest investigations over one of the biggest (pipeline) tragedies that this bill pays so little attention to those recommendations and actually steps backwards,” Carl Weimer, executive director of the Pipeline Safety Trust, a safety advocacy group.