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Bridges Article March 16, 2009
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Blood runs through rebar. It is common knowledge to a terrorist. For years Osama bin Laden, leader of Al Qaeda, has pointed a sword at the economic prosperity of the U.S. Bridges and tunnels are as attractive as an aorta.

A Blue Ribbon Panel (BRP), which consisted of bridge and tunnel experts from professional practice, academia, federal and state agencies, and toll authorities and was formed shortly after the 9/11 terrorist attacks, estimated in a report released in 2007 that the loss of a critical bridge or tunnel could cost the U.S. economy more than $10 billion.

To put it in more realistic terms, the BRP broke down the losses suffered by New York City. According to the report, Manhattan lost approximately 85,000 jobs, with about 28,000 of those positions linked to company relocations.

“As a result of the Sept. 11, 2001, attack, the PATH commuter rail line and station were rendered unusable,” the BRP report said. “The line carried 67,000 passengers each weekday to lower Manhattan and was closed for about two years. This was a major factor in the relocation of 103 firms, 1.1 million sq ft of office space and 11,700 jobs from lower Manhattan to New Jersey.”

When the I-35W bridge collapsed in Minneapolis in 2007, the region was hemorrhaging $400,000 a day. The demise of the old structure had nothing to do with terrorism, but the economic effects of the downing of a major span were realized during the 13 months the route was incapacitated.

Highly recommended

In general, the BRP report ripped off staggering numbers in an urgent tone.

“In many parts of the country, the transportation system is straining to keep up with the current demands of society and the economy,” it was reported. “The actions of terrorists can impose critical damage to some bridges, and, with explosive forces, exert loads that exceed those for which components are currently being designed.”

Among the 600,000 spans in the U.S., according to the BRP, preliminary studies indicate there are approximately 1,000 sites where substantial casualties, economic disruption and other societal ramifications would result from isolated attacks. The U.S. transportation system also carries 337 highway and 211 transit tunnels.

The BRP encouraged the prioritization of the 1,000 bridges and 548 tubes, which would be followed by a risk assessment that would be used as a guide for allocating federal and state funds to address the security concerns.

Cost-effective security measures would follow, as well as the development of engineering design standards in an effort to reduce the vulnerability of high-priority bridges and tunnels to terrorist attacks.

The BRP released its overarching recommendations to federal and state agencies. Below is a summary of suggested actions:

Institutional Recommendations

Interagency coordination—Recognizing the importance of both operational and engineered solutions and the expertise that exists within the owner/operator community, it is vital that the Federal Highway Administration (FHWA), the American Association of State Highway & Transportation Officials (AASHTO), the Transportation Security Administration (TSA) and other highway transportation stakeholders come together to make sure assessment methodologies and security solutions meet stakeholder needs.

Outreach and communication strategies—The FHWA and AASHTO, along with other organizations, need to distribute information about bridge and tunnel security as well as cost-effective countermeasures to decision makers, owners, operators, designers and politicians.

Clarification of legal responsibility—The FHWA must clarify the legal position of state departments of transportation and public transportation authorities in terms of their responsibility to act on risk assessments done on their facilities.

Fiscal Recommendations

New funding sources—New funding mechanisms beyond and outside of the current federal-aid highway funding sources need to be established.

Funding eligibility—Legislation should be amended to allow expenditures for cost-effective strategies for bridge security, the same measure that was taken for seismic retrofitting.

Technical Recommendations

Technical expertise—Security solutions should be created and FHWA, along with the TSA, should prioritize critical bridges and tunnels and should allocate funds to meet high-priority security needs.

Research, development and implementation—Technology should be developed and validated through appropriate research and development initiatives to establish engineering security standards.

The bigger the safer

When 9/11 went down, bridge owners and operators across the U.S. scrambled to check what security measures, if any, were in place. Since 2001, some spans have been tightened, but the exact number is unclear. Officials say many of the “large, signature bridges” have been looked at and strengthened, but structures below that elite group still may be vulnerable to terrorist attack.

“I would say we have been working hard at making our bridges, especially our largest and most critical pieces of infrastructure, much safer,” Ted Zoli, vice president and technical director for bridges at HNTB Corp., told ROADS & BRIDGES. “I would say that we have made a tremendous amount of progress since Sept. 11, but there is still work to be done.”

Zoli, however, stops short of assuring the safety of those bridges classified right below the signature spans in order of importance.

“There is a certain amount of second-tier bridges that are still very major, very significant structures that would have major regional impacts if they were successfully attacked, and those really have not been addressed,” he said.

Bridge owners and operators certainly would like to move that boiling pot of concern to the front burner, but funding, particularly for security purposes, has been slow to develop. Steve Ernst, senior engineer, Safety and Security, for the FHWA, believes those in the private sector are in a better position to guard their spans. When the dollar is small, many agencies choose to conduct simple maintenance on bridges over installing security items.

“Funding is always a concern,” Ernst told ROADS & BRIDGES. “It is hard when you have so many needs to concentrate on security, and it may not even be appropriate.”

The FHWA has certainly shown its concern when it comes to protecting airborne structures and the motoring public. Following a recommendation from the BRP, the FHWA has executed its component-level risk assessment. Developed by the U.S. Army Corps of Engineers, these 11?2-day workshops have been offered by the FHWA to educate owners and operators on what they need to secure. FHWA also conducts security assessments, where a special team is dispatched to assist in the design of a bridge.

“We will go out there and go through the process for them to decide some of the measures they could take,” said Ernst.

Several threats are evaluated when the risk assessments are conducted, including vehicle and hand-emplaced explosives, fire, impact and nonexplosive cutting devices.

When the time and money is right, bridge owners and operators can engage in a number of different security measures. Bridge hardening, making elements more robust, is a popular technique, but is expensive and usually considered for new construction. According to Zoli, the same manufacturers that fabricate armored cars are now using the same type of material to armor bridges. Hardening protects a bridge from air-blast effects, an area that has been studied extensively since 9/11.

Fire protection also can fall under the hardening category. Zoli said protective application systems, including paints, are available that release and create a char layer.

“It may start out as a quarter-inch thick then expand to five to 10 times its original thickness,” Zoli said.

An overpass forming a critical link of the MacArthur Maze outside of Oakland, Calif., is a real-life example of how quickly fire from an explosion can sever a major commercial artery. A gasoline tanker tipped and exploded on the elevated roadway that carries eastbound traffic from the Oakland Bay Bridge into I-580 and I-980 and State Highway 24. The fire was so intense that it melted the steel girders underneath the bridge deck in minutes.

Work also is being done in the area of cable sheathing, which until recently has not been fire resistant.

“The ones we have used in the past have not been very resistant to fire and there have been some dramatic failures,” indicated Zoli.

Fencing, increasing security staff, lighting and camera installations also have been used to ward off attackers.

However, if a prime goal of terrorists is to claim economic casualties, then response and recovery time is absolutely critical, Ernst believes. Although the known enemy did not hit it, the collapse of the I-35W bridge in Minneapolis provided a sterling example of how quickly the nation’s infrastructure system could be stitched. The contractor, Flatiron Constructors, had a new span up and running in just under 12 months despite a harsh Minnesota winter.

“That bridge may not have caused a dent in the national economy, but it probably did cause some problems in Minnesota,” claimed Ernst. “If you can put it back quickly and if you have a mechanism for putting it back quickly that is always wonderful.”

Cost, however, again comes into play. Expediting the completion of the I-35W bridge cost the state millions more in incentives, making some wonder if it is economically feasible.

“Time is money, so if there is an ability to cut down the time you also save money in operational costs,” said Ernst.

The original version of the I-35W bridge was a nonredundant steel truss bridge, and there may be thousands more just like it lying across bodies of water in the U.S. A non-redundant structure is especially prone to terrorist attack, because it only takes the failure of one member to collapse the entire structure.

Security gate bridge

The Golden Gate Bridge is on a short list of bridges in the U.S. that have been truly battle tested. In the 1920s, the Golden Gate Bridge District was involved in a permitting struggle with the Department of War. The fight lasted seven years. The government was against building a bridge across the San Francisco Bay due to an overwhelming fear that enemies would bomb the span and block the entrance into the port, which at the time housed a huge naval and army facility. Then in World War II, antiaircraft and machine guns, along with 150 national guard soldiers, protected the red icon.

“[Security] is something that has been on our mind,” Kary Witt, bridge manager for the Golden Gate Bridge, told ROADS & BRIDGES.

That mindset was shaken again in 1991 during the World Trade Center bombings before the world changed when the two towers were struck 10 years later.

“We were concerned [on 9/11] for a few hours because an aircraft was unaccounted for and reportedly headed for San Francisco,” said Witt.

The sidewalks of the Golden Gate Bridge were closed for months, and the National Guard stayed on until 2003.

The armed presence gave the Golden Gate Bridge time to assemble a security plan. More security officers have been hired, and the bridge’s security coalition, which was actually formed to calm the fears of the millennium new year, is now in place. The coalition, which consists of the Golden Gate Bridge District, which carries its own security force, the California Highway Patrol, the U.S. Coast Guard, the U.S. Park Police and the National Park Service Law Enforcement Rangers, has an open line of communication when it comes to protecting the structure. The Golden Gate Bridge also is in close contact with the FBI, a joint terrorist task force and RTAC, which is a state-run antiterrorist group.

The Golden Gate also has taken advantage of limited funding and various grant programs to install additional fencing and lighting around the span.

“We also have installed cameras and sensors. In total it has been several million dollars of equipment,” said Witt.

“The safest condition of the Golden Gate Bridge would be to not put anything on it,” he continued. “You have this balancing act between security and public access. One of the things we have placed a high priority on is maintaining access to the bridge by visitors who are walking or bicycling, and there are security risks that go along with that that we actively manage.”

Tube of concern

Tunnels bring something more to the table when it comes to security. When you are dealing with rail transportation, chemical warfare seeps into the equation. The FHWA executed a scanning tour of tunnel systems in Europe shortly after the 9/11 attacks and conducted a workshop in Irvine, Calif., in 2007. European experts were called on to offer advice on tunnel safety to state engineers. According to Ernst, perhaps the most impressive anecdote coming out of Europe is the creation of one-button response. With one-button response, a tunnel operator has an operation protocol in place where he or she can literally press one button to respond to an event, like a fire.

“He pushes one button and the gates go down, the ventilation system is activated in the proper way, emergency lights are on, the fire department is dispatched,” Ernst said.

Most of the tunnel systems in the U.S. are aging structures, and Ernst did say retrofitting them to make them safer would be expensive.

However, the FHWA does have an Advance Notice of Proposed Rulemaking for its Tunnel Inspection Program, which was still open for public comment at press time.

Work will never end

Since the BRP’s recommendations, the road and bridge industry has assembled an engine block in terms of a security strategy, but it appears many of the components have yet to be greased. The 9/11 attacks created a solid link between the FHWA, state DOTs, the FBI and the Department of Homeland Security, a link that was in virtual pieces before that dark day. Innovations also have sprinkled the region, with perhaps the most important being FHWA’s component-level risk assessment.

Funding, however, continues to be the sticking point. It appears that if it is a major signature span or one from the private sector, many of the precautionary measures have been put in place. However, for a majority of spans it is a relative unknown if any security maneuvers have been executed.

“I think we are going to always be working on the issues,” said Ernst. “We probably are not going to protect every critically important bridge, but we can always in our new designs incorporate security so when we build new bridges we can make them more robust. I think that’s the key.”

“I think one of the challenges going forward is to keep those recommendations in front of legislators,” added Witt. “The further we get from Sept. 11 the less urgent those recommendations become, especially when we are faced with all other kinds of crises. History has shown that [terrorists] are very patient. They will wait until we lose interest in homeland security.”

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