Cities and Fixed Infrastructure
Today, more than 220 million Americans (some 80 percent of the U.S. population) live in and around our cities, and over 160 million live in major metropolitan areas (with populations that exceed a million).1 American cities are often seen by those in less developed lands as monuments to our freedoms, our lifestyles, and our wealth—and in some ways, our excesses. For these reasons, and because of their abundance of high-value targets, our cities and their inhabitants have also become the object of terrorism schemes (U.S. Conference of Mayors, December 2001; U.S. Census, 2000).
Cities are by definition target-rich environments for terrorism, whether the aim is people or economic damage. The fixed infrastructure elements of the city—which include the utility systems that provide the essential services of water, electric power, and fuels distribution, digital and voice communications, and waste collection and disposal—are highly interdependent. Highways, roads, bridges, and tunnels provide another kind of target (PCCIP, 1997). Tunnels present particular opportunities because they form extensive networks beneath our cities that enable railroads and highways, transit service, sewage collection and transport, and conduits for utilities.
Cities also contain many attractive “surname” targets. Terrorist attacks on notable buildings, along with ballparks and similar public places where large
numbers of people gather, could be both casualty-rich and newsworthy. Unique facilities such as high-profile universities and national research centers are another set of distinctive potential targets.
Emergency operations centers (EOCs) have become a critical part of the operating infrastructure of major cities. They provide the essential responses for cities and their people during floods, hurricanes, and other natural disasters; during major fires and other domestic disturbances; and now, during terrorist attacks. Thus cities face two challenges associated with their EOCs: the need to upgrade them so that they are prepared to handle terrorist attacks and the need to protect EOC facilities and staff, as they could be targets of terrorists seeking to enhance the impact of other attacks.
The loss of any of these potential targets would, by itself, be serious, but multiple losses, the result of simultaneous attacks on different types of targets, could be devastating. For example, the fires in buildings caused by an attack could not be extinguished if, in a coordinated attack, the relevant water-supply pumping stations were put out of service. The close interdependence of such targets greatly increases cities’ vulnerabilities (Dean, 2002).
The elements of cities that must be addressed in order to deter and, if need be, respond to terrorist attacks include the following, each of which is addressed in a subsequent section of this chapter:
Emergency management and emergency operations centers,
Water supply and wastewater systems,
Electrical supply interruption,
Urban information technology and communications,
Urban transportation and distribution systems,
Major and monumental buildings,
Stadiums and other places for large public gatherings, and
Underground facilities, including tunnels.
EMERGENCY MANAGEMENT AND EMERGENCY OPERATIONS CENTERS
Major cities and many large counties have emergency response plans providing for local EOCs and their personnel to respond to crises such as a natural disaster. Responding to terrorist attacks is a relatively new dimension for EOCs. As such, there is a significant and immediate need for appropriate response guidelines, threat-scenario definitions and training procedures, special or improved equipment, and federal funding to support EOCs across the country in achieving an adequate level of preparedness (U.S. Conference of Mayors, December 2001).
An EOC is a complex organization whose success is directly related to the capability of its communications systems and the competence of its staff to handle intra- and intergovernmental operations in a crisis. The EOC must coordinate, by prearranged plan and agreement, the efforts of key leaders beginning with the mayor, city hall staff, and the directors of police, fire, and emergency medical services. Also integral to the EOC mission is interaction with senior officials from public works and public health departments, utilities, and mass care and mortuary facilities. The EOC should also have direct communications links with the control centers intrinsic to the railroads, highway and transit systems, public utilities, communications facilities, and various neighboring and mutual support organizations.
An EOC is the crisis command center for a city. As determined by its assessment of the event, the EOC must properly activate the triage structure for allocating resources and personnel that assure effective control of the immediate crisis and any cascading damages. Because timely information and analysis are essential, the EOC must be in a position to readily communicate not only with principal players in the crisis response but with governments and the public. The EOC is also expected to provide an information system to capture all pertinent event records. Clearly, in an attack crisis, the EOC is a critical asset for the city and its people.
High on the list of vulnerabilities for these densely populated areas is the possible loss or incapacitation of its EOC and its trained and experienced leadership. A variety of methods could be employed to damage the EOC and its staff, including military weapons, explosives, fire, and gasoline or other volatile mixtures. EOCs are particularly vulnerable because in most cities, their facilities are neither hardened nor necessarily easily protected, having been designed to handle responses to natural disasters.
Among the most valuable assets of the EOC are the first responders. Typically these are the police, firefighters, and emergency medical service (EMS) personnel who are the first to answer a call. First responders must quickly assess and report the situation they find; protect, rescue, and provide initial care for casualties; and safeguard property. In a terrorist attack, first responders will likely be at greater risk because of their limited ability to determine the cause and extent of the situation they find. Moreover, a terrorist could try to deliberately kill or injure as many first responders as possible in order to leave the remainder of the city more vulnerable to further attack.
For the first responders, knowing what toxins are present in the smoke and dust from an attack becomes the difference between life and death. Those engaged in this work speak of their concern for getting through the first 30 minutes. Of particular need is a quick means to test the air they must work in; air sampling
and testing kits in general use today are too slow. More concerned with victims than with their own welfare, first responders will routinely put on their breathing apparatus to enter a site without first performing tests. If the smoke and dust happen to contain dangerous toxins for which their apparatus is not a safeguard, the lives of the first responders may be lost.
The effectiveness of the EOC operation is directly related to how well, and at what level of confidence, its communications systems operate. In desktop training and simulated event testing, the EOC usually communicates well with police, fire and EMS units, but in real events the situation may change rapidly and planned procedures may not be as effective as intended. Communications equipment must operate reliably in the presence of products of fire and explosion, and when located in suboptimal places. In the World Trade Center (WTC) attack of September 11, where transmission repeaters apparently failed, the situation rapidly broke down; command and control staff could not communicate with their units engaged in the first response (Dwyer, 2002). As a result, first responders, although following the plan, were lost.
Adding to the responsibilities of the EOC, as the significance of an attack becomes known, mutual support and neighboring units—including county, port and other special-purpose district and state and federal personnel—will begin to arrive and the problems with communications interoperability will increase. The radios of one agency do not, by design, readily net with those of others. This communications barrier increases the danger to a city and its inhabitants during a terrorist crisis. Technology exists that could ease this problem, and policy changes and new technology could eliminate it altogether.
Implementation of Existing Technology
Vulnerability of EOC Sites and Facilities
Recommendation 8.1: FEMA, working with OHS and in conjunction with state and local agencies, should develop a recommended requirements list (RRL) of the facility characteristics, expertise, and equipment required to withstand a variety of terrorist attacks and then assess the EOCs of the major cities to determine their greatest near-term needs for improvements in physical makeup, equipment, preparedness, and plans for recovery if damaged. System redundancies and communications assets should receive particular attention. From this assessment, priority attention should be placed on bringing the neediest EOCs up to minimum standards. The city governments should share the costs of such upgrades to ensure that local authorities are committed to the project.
The RRL should be provided by the federal government to assure consistency across all EOCs and across the country. The agency best suited to prepare
such a list, under present relationships, would be FEMA. Yet because of new and wide-ranging terrorist threats, FEMA should jointly develop the requirements list with OHS (the Homeland Security Institute recommended in Chapter 12 would provide useful data and analysis), OSTP, DOJ, and DOD. EOC professionals and county and city governments should also be represented. FEMA’s scope is officially expanding to include preparation for responses to terrorist attacks (FEMA, 2002). The background and working skills of the FEMA staff may not currently be exactly suited to undertaking all the necessary tasks, so close collaboration with numerous other agencies will be essential.
Recommendation 8.2: In the near term, the assigned federal roles and responsibilities of FEMA, OHS, and other federal agencies (DOJ, NSA, DOD) must be reviewed and clearly defined with respect to preparedness oversight and support of the nation’s emergency operations centers. These definitions should be published in the Federal Register and made generally available through publications issued by FEMA or OHS for the benefit of all parties involved.
Intra- and Intergovernmental Operations
Training is needed to meet intra- and intergovernmental challenges under the stress of emergency conditions (President’s Commission on Critical Infrastructure Protection, 1997). Different requirements and needs; different reporting, equipment, tactics, and training; different funding and budgeting practices; unique vocabularies and acronyms; and preexisting attitudes are some of the problems to be faced when mixed-unit operations occur. There is much to be said for deploying simulation models and training modules designed to familiarize staff with threat scenarios and improve the effectiveness of collaboration among agencies and governments.
Recommendation 8.3: In the near term, intergovernmental working groups (federal, state, county, and city), perhaps locally sponsored but following federally issued guidelines, should be established to gather critical information. They should report their findings on the preparedness of each EOC, and of the corresponding state and federal support units, for a terrorist-attack crisis. This information would also provide input for the development of simulation models; weaknesses should be addressed by responsible local leaders.
Vulnerability of First Responders to Toxins
There is a great need for the capability to identify toxins in the smoke and dust within just a few minutes after an attack (CERF, 2001). No immediate solutions are available, however, unless the military has kits for such analysis.
Radio Communications Vulnerability
The failure of radio communications between responders to an attack has both technical and policy dimensions.
Recommendation 8.4: In the near term, changes to equipment, training, and policies must be identified and introduced at the local level to immediately improve the interoperability, reliability, and clarity of radio communications used by EOCs and first responders in crisis situations.
Research and Development Priorities and Strategies
Vulnerability of EOC Sites and Facilities
Recommendation 8.5: Current EOC vulnerabilities, including those of existing locations and their technical systems (communications; data and video processing; heating, ventilation, and air conditioning; site hardening; and other elements to be identified), must be assessed. Thereafter, federal, state, and local government agencies should cooperate in planning the needed improvements. These plans might include the determination that the only way to provide secure command, control, and communications capabilities is by rebuilding some of the facilities. The option of duplicate or mobile EOCs should be a part of this longer-term (3- to 5-year) examination.
FEMA should take the lead in these longer-term assessments as a continuation of its near-term assessments recommended earlier. Coordinating closely with local authorities, it should identify specific EOCs that require significant upgrading or replacement.
Intra- and Intergovernmental Operations
In the longer term, simulation models based on terrorist threat scenarios must be completed, field tested, authenticated, and deployed, along with corresponding training modules. Extensive coordination between city, state, and federal participants will be required to make this effort succeed. The simulation and training tools will bring the EOCs, along with supporting units in government, to higher levels of preparedness.
Recommendation 8.6: Research, development, and production of simulation models and corresponding training modules for EOCs is needed in order to improve terrorist-threat recognition, resource utilization and allocation, intergovernmental and intragovernmental operations, and public information management and media relations.
Recommendation 8.7: These simulation models and training modules should be deployed as soon as possible to identify weaknesses in systems and staff and to test and qualify emergency operations teams.
Recommendation 8.8: The simulation models and training modules should be used for EOC testing and evaluation under federal controls. This should lead to certification, according to federal standards, of EOCs throughout the country and their crisis management teams.
This program must be undertaken on an expedited basis, with FEMA as the expected lead. The threat-based simulation models could be developed by systems analysis experts in the Homeland Security Institute recommended in Chapter 12 as support for OHS. Representatives of the EOC professionals should participate in this development and testing. FEMA would undertake the full implementation of these tools and would conduct the certifications testing in due course.
Vulnerability of First Responders to Toxins
Robotic units with intelligence would represent the best solution for first entry into the site of an attack in order to test the air (autonomous robotic technologies are discussed furthur in Chapter 11). But a simpler solution (if feasible) would be a self-contained, clip-on device that could instantly analyze the air and signal to a first responder whether it contained dangerous toxins. The device would not need to tell what the toxins are or to measure their concentrations, but would simply answer the question, “Is it safe for me to be here now?” If the answer is no, the unsafe site could be sealed off and a specially trained and properly equipped team summoned. Such sensor units, with enhanced support systems, could also be an asset for national intelligence organizations and perhaps for the United Nations Arms Inspections Service.
Recommendation 8.9: Research and development should be directed to creating a special-purpose sensor and supporting system (with its own appropriate set of sampling, calibration, and verification databases) to analyze the air for first responders at the site of a terrorist event. The self-contained, clip-on device would instantly determine if the smoke and dust at the site contain dangerous toxins and signal safe or unsafe.
Recommendation 8.10: Research and development are needed to develop even more sophisticated technological solutions that would enhance the safety of the first responders, such as robotic units that have suitable intelligence and mobility and are affordable for cities and EOCs.
This research and development should occur at the federal level in the many government laboratories with existing programs in sensors and robotics. NIH and emergency-response professionals should participate as well.
Radio Communications Vulnerability
There are at least three challenges in this area: (1) equipment and technology, (2) availability and use of specified frequencies and standards, and (3) funding. Policy changes by the Federal Communications Commission (FCC) and suitable new standards would allow the United States to replicate the solutions now working in Europe, where a common frequency has been established in the best area of the broadcast spectrum for emergency-use radios (Mayer-Schonberger, 2002). Given the proper incentives, it is expected that the radio communications industry would willingly develop the needed technology, including repeaters, base stations, and mobile units. The federal government could expedite this progress by accelerating FCC changes and funding the implementation of the solutions, thus providing confidence that the strategy will be sustained. These critical improvements will occur only if the federal government assures that the new emergency communications units will be supported by policy and standards and will definitely become the required norm. This issue is also addressed in Chapter 5.
Recommendation 8.11: The Federal Communications Commission (FCC) must be urged to make policy changes and promulgate standards that would allow the United States to replicate solutions now working in Europe, where a common frequency has been established in the area of the broadcast spectrum that is best for emergency-use radios.
Recommendation 8.12: Focused development should be directed to prototype communications units that meet the requirements of the EOCs.
While the entire EOC program to improve communications should be under FEMA, the policy issues that have to be dealt with would engage FCC, the Congress, and perhaps DOJ. The OHS and the national laboratories should be involved in the development and testing of the technical solution, and industry should play a central role. The equipment development could effectively be done under a public–private partnership formula, and the resulting technology might be adapted by the radio-communications industry into an attractive commercial product line.
Federal funding should be made available to cities in order to expedite changeover to the prescribed communications systems.
WATER SUPPLY AND WASTEWATER SYSTEMS
The water system consists of four parts: (1) supply, (2) treatment, (3) distribution, and (4) sanitary removal. The supply system comprises reservoirs, dams, aquifers and wells, and the aqueducts and transmission pipelines that deliver
water to distant users. The treatment system comprises filtration and other plants that remove impurities and harmful agents and sanitation facilities (e.g., chlorination) that kill biological contaminants. The distribution system comprises pressure-regulating reservoirs and towers, piping grids, pumps, and other components that deliver water from treatment system to final user. The sanitary and waste removal system comprises sewer and related collection systems that deliver waters contaminated with household and industrial wastes to sanitary treatment facilities, the facilities that process these wastewaters, and the outfall facilities that return recycled waters back to the natural environment. Finally, storm sewers collect and convey storm water runoff to treatment and/or discharge to the environment.
Parts of the U.S. water infrastructure date to the 19th century. Their age and deterioration make them vulnerable to disruption. Also, physical security is inadequate; at many locations, the public has unrestricted access to reservoirs and transmission systems. As in the case of other infrastructure networks, should the water supply system fail, we would want it to do so gracefully. Cities such as Boston, New York, Los Angeles, and San Francisco are served by aqueducts, which if lost from service may have cascading effects; more attention should be given to the interconnectedness of water supply systems and water transfers.
There are over 76,000 dams in the United States. Dam failures can result in thousands of deaths and immense costs. As an example, should the Glen Canyon Dam on the Colorado River fail, the resulting flood would overtop Hoover, Davis, and Parker dams downstream, disrupt the power grid of the Southwest, destroy irrigation in southern California, and flood the Imperial Valley. On the other hand, inducing a structural dam failure is difficult. Still, recent vulnerability studies performed for the U.S. Bureau of Reclamation have led to a precautionary measure: restrictions on truck and boat traffic at some of the agency’s dams.
Concrete gravity and earth embankment dams are massive structures that hold back river flow by their sheer weight. Large explosive energies are needed for their destruction. At the building of the Aswan High Dam in 1964, the Egyptian government concluded that a terrorist explosive device of a size large enough to breach the dam would more likely be used against a city than the dam and downgraded the threat. Concrete thin arch dams, light structures that serve as diaphragms across a narrow gorge, are more susceptible to explosive attack. Military experience suggests that even thin arch dams are difficult to destroy by bombing from the air; although a truck bomb on the crest of a thin arch dam at full pool could allow water to overtop the structure, few dams can sustain significant overtopping. However, the United States has relatively few of these struc-
tures. An earth dam can of course be breeched with conventional earthmoving equipment, but this would require unrestricted access for many hours.
About half the U.S. water supply comes from groundwater, generally unfiltered. Wellheads are easier targets than dams, because they are dispersed and little protected, but their physical destruction would not be a threat to life; the response time for such disruption could be days to months. The principal threat lies in the potential for introducing contaminants at the wellhead, not in physical destruction.
The waters collected at dams or wellheads are transferred over long distances in pipelines and aqueducts, typically by gravity with occasional pumping stations. For example, the San Francisco water-supply aqueducts from the Sierra Nevada transport water 150 miles. Most aqueducts are covered, but not all. The California Aqueduct carrying water from the Sacramento delta to southern California is an open channel for much of its 400-mile length. Aqueducts are designed to withstand hazards such as earthquakes, and some have systems for monitoring such natural disasters and responding to them, if necessary. These systems could be enhanced to handle attacks.
Sanitary collection systems are also vulnerable and pose the threat of significant disruption to normal societal functioning, if not to loss of life. Metropolitan areas cannot long function without the prompt and efficient removal of sanitary wastes. Loss of sewer services can make cities essentially uninhabitable, possibly requiring large-scale vacating of homes and businesses.
Gasoline or other flammable or explosive liquids allowed to flow into the sewer system pose the potential for explosions. Such an event killed 200 people in Guadalajara in 1992 (Eisner, 1992). Sewer explosions caused by the illegal or inadvertent release of flammable liquids are not uncommon in the United States.
More threatening than physical disruption is the potential chemical, biological, or radiological contamination of the water supply. Deininger (2000) discusses biological agents and industrial chemicals that could be used to taint drinking water. Even if the mortality or morbidity caused by contamination were minimal, the psychological effect of a credible threat to the water supply could be significant. No one willingly drinks water suspected to have even trace contamination.
The potential points of contamination of the water supply are the following: upstream of the intake of a water supply, at the water intake or wellhead, at the treatment plant, or at a point in the distribution system. The threat of upstream or collection point contamination is limited by the large volumes of water and thus the dilution involved at that stage, and by the effect of filtering and sanitation at the treatment plant. Yet, certain biological agents or their toxins may be very hazardous at low concentrations, and water treatment plants are designed to remove only a special set of contaminants, typically those found in nature. A further concern is that the water supply in several U.S. cities is not filtered. Thus,
contaminants that are not neutralized by chlorination can pass through these systems into distribution.
The greatest vulnerability to contamination is at the distribution level. Downstream of the water treatment and sanitation works, any contaminant that enters the system has the potential for traveling unimpeded to end users. A scenario of concern to many water districts is the potential for backflow into the distribution system from any household connection or hydrant. This might affect a few thousand households (Dreazen, 2001). These agents could arrive in concentrations high enough to be harmful and would be subject to only residual levels of chlorine in the water. The contamination could be targeted to specific end users, such as those in a government building.
Water treatment involves hazardous chemicals in large quantities, specifically chlorine. At the time of the Pentagon 9/11 attack, a string of railroad tanker cars filled with liquid chlorine sat across the Potomac at the Blue Plains treatment works. Chlorine, sulfur dioxide, and other dangerous chemicals are routinely used at every water treatment plant.
Implementation Issues for Existing Technology
It makes little sense to improve the security of our water system against terrorism without addressing the history of deferred maintenance of the water infrastructure. One of the best and most cost-effective ways to make the water infrastructure more robust against malicious threats is to return its physical condition to a satisfactory level of repair. Initiatives by the federal government to develop a nationwide process and a plan for funding of rebuilding water-supply systems are necessary steps.
Water Industry Slow to Change
The water industry has not traditionally been fast-moving. When the U.S. Environmental Protection Agency (EPA) proposes rules, compliance typically spans a decade or more. Outreach and communication is needed to reduce the “time constant” for change in the water sector. Meanwhile, add-ons to existing technology may provide the best opportunity for improvement because they are more easily accepted by the industry than radically new technology.
Facilities Open to the Public
Many parts of the water-supply infrastructure are highly accessible, partly as a result of multiuse provisions written into public funding legislation. However, control of public access to components of the water system is critical for security
and needs to be improved. Modification of certain provisions should be explored so that current legislation continues to adhere to its original spirit while also allowing authorities to introduce selective physical security for sensitive parts of the system.
Lack of Standardization
Because water systems are typically designed, constructed, maintained, and owned by local water companies or authorities, there is little standardization. This impedes the introduction of new processes and technology. Further standardization is needed, however, across local jurisdictions that control water supply, distribution, and treatment; in that way, neighboring providers may assist one another, and the people that they serve, in a crisis. In addition, because some local jurisdictions do not work well together, mutual aid and cooperation pacts need to be created before a crisis arises.
As noted above, several major cities develop their water supplies in remote locations and bring that raw water to the cities through long and often unprotected aqueduct conduits. Stocking sections of replacement conduit and developing scenarios and plans for rapid repair could lessen the threat of extended loss of raw water supply if sections of the aqueduct were destroyed by a terrorist act. Those responsible for systems dependent on aqueducts should take these and other appropriate steps so as to be better prepared for a possible attack.
Reluctance to Test for Exotic Contaminants
The water sector’s history of research on exotic contaminants, drought management, and systems analysis could be reevaluated for the lessons it teaches for security. The availability of specialized water testing is limited in most parts of the country, however, and legal liabilities make laboratories reluctant to participate in testing. This constraint could be removed with revisions to applicable laws; the dearth of laboratory capacity poses a serious limitation to our ability to respond to a contamination attack on the water system. Furthermore, terrorists could use a variety of contaminants. We need to evaluate a tiered approach to testing, beginning with broad characteristics that suggest change from a baseline. Examples might be change in total organic halide, change in ultraviolet light absorbance, or change in refractive property.
Recommendation 8.13: Identify and implement revisions to applicable laws or statutes, thereby removing the constraints to testing public water supplies for dangerous contaminants that might be employed by terrorists. Take
other necessary steps to assure that adequate laboratory testing capability and capacity are available for local water utilities.
OHS should work with DOJ and EPA, along with representatives of state and local water supply agencies, in seeking solutions. It is likely that the constraints are based in state law or county or local ordinances and so must be addressed there. These bodies should be ready to cooperate because it is their water supply that is at risk.
Research and Development Priorities and Strategies
The four highest-priority areas for research on water security are physical security, monitoring and identification of biological and chemical agents, decision models and sampling, and interactions across infrastructures. In addition, there is a need to establish a national center of excellence to support communities in conducting risk assessments and to serve as a clearinghouse for communicating research results to the industry. The scope for such a center would become broad, and multiple branches with well-defined missions added when the need is defined.
The water infrastructure enjoys little physical protection. Much of the supply, transportation, and distribution system is unstaffed and readily accessible to the public. New methods for physically securing the system are needed, as are ways of continuously—or at least periodically—monitoring for intrusion across the large areas that water systems cover. As with other physical infrastructure systems, technology is needed to protect against explosives delivered by motor vehicle or rail. The American Water Works Association is currently sponsoring vulnerability and physical-security training for water system operators, and EPA is funding the national laboratories to conduct the actual training.
Monitoring and Identification of Biological and Chemical Agents
A significant issue in contamination of water is the early detection of chemical or biological agents in the system. While water supplies are routinely monitored for a few contaminants, they are infrequently tested for exotic contaminants that might be introduced by terrorists. Much can be done to improve the situation.
New sensors for better, cheaper, and faster sensing of chemical or biological contaminants in water are needed, based on sophisticated analytical techniques that are available in the U.S. chemical industry. These sensor systems should be small, distributed, resistant to interference, and robust against false positives. For
simplicity, such sensor systems might focus on baseline properties like turbidity or ultraviolet absorbency, which may be indicators for the addition of a contaminant.
Conventional wisdom holds that water’s dilution effects would necessitate large quantities of contaminants to pose health problems, but this conjecture is poorly supported by research. The point needs more careful analysis to determine precisely what agents, and in what quantities, pose a serious threat if present in a potable water supply. Further, sensors should be deployed that will be effective in continuously testing the water supply to determine with confidence whether it is safe. If installed in distribution systems, these sensors would likely be effective at determining the presence of backflow-introduced contaminants.
Recommendation 8.14: Research and development are needed to create sensors and supporting systems for monitoring the safety of drinking water. These sensor systems would continuously test the water supply for agents in sufficient concentrations to pose serious threats; they would signal a response site, or automatically close valves, as needed.
Decision Models and Sampling
Important research questions include what to monitor and sample in the water system, as well as when and how; what inferences to draw from the data; and what the resulting optimal decisions should be.
Recommendation 8.15: Research should be undertaken on water sampling schemes to determine what types and population of data points are required for a spatiotemporal network and on intelligent decision processing to be able to reliably recognize the pattern of attack indicators vs. natural hazards. Such research would require that priority attention be given to the development of simulation models that would both analyze and simulate events and serve to train operators in systematic recovery, emergency response, and evacuation.
Interactions Across Infrastructures
The water infrastructure depends on electricity to control pumps, valves, and other mechanical components, as well as to power sensor, computer, and telecommunications systems. Disruption to the supply of electricity would thus have a major effect on water supply and treatment. Similarly, an important design requirement of most urban water systems is adequate water pressure for fire protection; an attack that ignited urban fires and disrupted the high-pressure hydrant system at the same time could therefore cause great damage and loss of life. Research is needed to understand the extent of these interdependencies and to create strategies for effectively dealing with them. This is a crosscutting issue that is covered in Chapters 10 and 11.
In addition, the water supply, treatment, and waste removal system is public infrastructure, owned and operated at the local or regional level or by private interests. Much of the support for rehabilitating and securing this infrastructure will have to come from local resources, complemented by federal funding through agencies such as the EPA, the Army Corps of Engineers, the Bureau of Reclamation, and others. The growing privatization of water supply and treatment introduces new uncertainties over improving security. Further research remains to be done on the effect of increasing water supply security requirements on the willingness of the private sector to assume the attendant risks under today’s laws and insurance markets. Should the private sector abandon this market, at a minimum, municipalities would have to find the funds to take over the utilities and the expertise to operate them.
ELECTRICAL SUPPLY INTERRUPTION
In the modern city, virtually all basic needs—food, water, shelter, employment—are dependent on the continuing supply of electricity. Interruptions for a few hours or even a day may be tolerable, but weeks or more without electricity could be devastating. Because cities become dangerous and unlivable places without electricity, urban electrical-supply systems must be made tougher and more reliable. This subject is treated in Chapter 6, “Energy Systems.”
INFORMATION TECHNOLOGY SYSTEMS AND COMMUNICATIONS
IT systems and communications have also become indispensable to city life, and their disruption could prove costly. They are addressed in Chapter 5, “Information Technology.”
TRANSPORTATION AND DISTRIBUTION SYSTEMS
From foot traffic to automobiles to cargo ships to airplanes, cities include virtually every known form of transportation—along with their vulnerabilities. This subject is discussed in Chapter 7, “Transportation Systems.”
MAJOR AND MONUMENTAL BUILDINGS
Recent experience indicates that buildings at risk include key symbols of American wealth and political power such as the U.S. Capitol building, the White House, and the New York Stock Exchange. They also include high-rise office buildings, such as the Empire State Building, the Sears Tower, and the
Transamerica Building, that occupy special places in the public consciousness. Entertainment complexes might also be targets, and though coordinated attacks on a few day-care centers would not cause serious economic damage, the emotional toll would be enormous (NRC, 1988, 1995, 1999).
Major and monumental buildings, like most others, are vulnerable to structural failure induced by various combinations of impact, explosion, and fire. In addition, the occupants may be threatened by toxins. Scenarios suggested by recent events include the impact of commercial airliners, business jets, and small private planes. The few incidents involving piston-engine impacts with tall buildings, including the 1945 collision of a B-25 with the Empire State Building and the 2002 crash of a Cessna 172 light plane into a building in Tampa, suggest that these aircraft had insufficient energy and fuel to cause great general damage or to precipitate collapse. Intermediate-size jet aircraft of the kind used by large businesses for their executives, on the other hand, might pose a threat. Impact by commercial airliners is unambiguously catastrophic, as recently witnessed.
Prior to September 11, 2001, bombs were considered to be the principal threats to buildings. Information about such bombs may be found in the FBI’s Bomb Data Registry and the Bureau of Alcohol, Tobacco and Firearms (ATF) histogram of actual events. The magnitudes of such attacks on U.S. targets have so far been limited by the size and capacity of trucks permitted to park or circulate in the immediate vicinity of the target buildings.
Impacts and explosions, as illustrated in Oklahoma City’s Murrah Building and the 1993 and 2001 attacks on New York’s World Trade Center (WTC), can destroy key structural elements, allowing gravity to destroy much or all of the building (ASCE, 1996; Corley, 1998). Some structures (such as those designed for minimum weight) could be seriously jeopardized by the loss of just a few columns. Temperatures of 500°C reduce the strength of common structural steels by 50 percent, and 1000°C reduces the strength to near zero. Columns, floor diaphragms, and connections between the columns and floor joists are the vulnerable members (ASTM, 1998).
In reinforced concrete members, the fire resistance is integral because a thickness of concrete covers the embedded steel reinforcement, protecting the steel from the fire temperatures. With steel members, resistance is presumably achieved, by code, with a layer of fireproofing. But this superficial coating may not be applied properly, or sections of it may be removed from the structure over the course of time, thus compromising the level of protection. The forces from a major impact or explosion also may strip fireproofing from structural elements and assemblies, destroy detection and alarm circuits, break pipes and deplete the available water supply for fire protection, and render smoke control and alarm systems ineffective.
Details of how the fire contributed to the collapse of the WTC towers are still being studied. Some estimates suggest that the jet fuel probably burned out within a few minutes of impact, but not before igniting building materials and contents on multiple floors simultaneously. This would mean that the fires were fed primarily by materials that are equivalent to those in most other high-rise office buildings. The 1988 First Interstate Bank fire in Los Angeles and the 1991 One Meridian Plaza fire in Philadelphia burned out multiple floors in very intense fires fed only by the ordinary combustible furnishings and finishes within these office buildings (Nelson, 1989; Routley et al., 1991), but they did not collapse. An important issue, then, is whether a similar fire in the WTC and or similarly constructed megastructures could cause the building to fall even without airliner impacts.
Single, localized ignition is assumed in building design (Ingberg, 1928). However, a low-grade explosive incendiary device or other method of starting multiple small fires could potentially cause enough damage and spread fire over a large enough area to overwhelm the building’s sprinkler system and lead to an uncontrolled fire. Redundant water supply for fire protection and/or redundant sprinkler systems might provide additional protection for these situations and for some types of attacks.
In addition to damage to the building itself, the hazards of impact, explosion, or fire also include flying glass shards (there may literally be millions of them) and airborne toxins.
Heating, ventilation, and air conditioning (HVAC) systems could disperse airborne materials. While most HVAC systems in new buildings are partitioned, serving groups of several hundred people or fewer, older HVAC systems may serve much larger areas. In some high-rise buildings, openings for elevators and plenums run the entire height of the building, creating a chimney effect. Outdoor air enters the building at the lowest levels and rises to the top as it is warmed. These paths provide a ready mechanism for distribution of toxins throughout the entire building.
One way to prevent HVAC units from becoming the entry point for toxic agents is to restrict access to the outdoor air intakes and fan rooms. Outdoor air intakes are commonly located in the walls of buildings, accessible to the street level. In existing urban high-rise buildings, relocating them would be quite expensive and therefore unattractive to building owners. Rooftop HVAC systems are less vulnerable. In new buildings, outdoor air intakes can more easily be protected, and fan rooms can be secured. Such changes are achievable through building codes. While most HVAC systems use air filters, they are not capable of removing many types of toxins. Filters that could remove both biotoxins and chemical toxins are available, but they are costly to install and operate. Few building owners would find them worthwhile in today’s real estate markets. However, filters to remove just biotoxins (e.g., anthrax) can be installed and operated; these might be a reasonable compromise. Meanwhile, no technology is
currently available to quickly and accurately sense the presence of toxins in HVAC systems and building shafts and automatically initiate responses. Smoke detectors in use today can initiate certain actions, such as shutting down the HVAC. A more sophisticated approach would involve developing new sensors and installing them in HVAC systems that could isolate dangerous toxins in one area of building as soon as the threat is recognized. These sensors could use the same core element that was described earlier to protect first responders.
Implementation of Existing Technology
Historically, the blast engineering of buildings evolved in response to the most recent destructive event. For example, explosions producing extensive amounts of flying glass led to better glazing systems that include robust frames and mullions, films, and composite glazing. The main barrier to wide application of this latter technology, which has two broad categories, is cost. Structures such as courthouses use standard glazing with laminations to resist shattering, and robust frames and mullions; the cost of these systems is typically 25 percent more than glazing with no blast resistance. State Department criteria lead to glazing approximately two times thicker than conventional systems for the lower 10 to 15 stories; the cost is typically 100 percent greater than glazing with no blast resistance. Another component of cost is conservatism arising out of approximations in CONWEP and BLASTX, the most commonly used software for predicting blast pressure. These approximations are often accepted in preference to undertaking costly three-dimensional, computational-fluid-dynamics (3D CFD) models. Recalibration of BLASTX is needed.
Close attention has been given to the blast engineering of column design, especially for steel column splices, which are typically built to resist global structural but not local bending. Blast loading requires splices to resist local bending as well. Implementation of this technology is hampered by construction cost, magnified by uncertainty in the requisite analysis.
Better knowledge of the engineering properties of masonry (such as that employed to build the U.S. Capitol) and of aged reinforced concrete (such as that at the Pentagon) is needed to exploit advanced analytical techniques. Another benefit would be to introduce new materials such as Linex, a spray-on, self-bonding elastomer that has been tested in Israel with U.S. participation. Linex increases the ductility of masonry walls, such as the inside surface of the brick at the Pentagon.
In crowded urban areas, where adequate standoff distance or blast walls are impractical, new structures should consider new materials such as stainless steel curtain walls. Also, louvers and plenums for air-conditioning may occupy up to 20 percent of the lower-floor wall-surface area, creating a soft spot in the building skin. Alternative designs might reduce such vulnerability.
Fire resistance ratings currently in use in the United States should be cor-
rected. They have been rendered obsolete by available technology. Design methods used in other countries, and their technological bases, should be surveyed for possible use in the United States. In lieu of the time-consuming testing and certification process required to change our codes and standards, provisional changes to current practice could be made by utilizing the existing building regulations in such countries as Sweden, Australia, and New Zealand.
Research and Development Priorities and Strategies
Recommendation 8.16: It is essential that research and development be undertaken that leads to the improved blast- and fire-resistance of major buildings. The results of this research must then be disseminated so that new knowledge is incorporated into the design and construction of new buildings and into the remodeling of existing buildings. The specific areas of focus should be the following:
Testing and codification of blast-resistant curtain-wall technology;
Testing and codification of blast-resistant glazing and software (e.g., BLASTX and CONWEP) for evaluating glazing systems, including mullions and window frames;
Materials testing and analysis of fire resistance (including full-scale tests of burning aircraft fuel and common building materials) with respect to the following:
Building structural systems;
Missing or deficient insulation;
Fire-induced thermal conditions within an enclosure, including ventilation effects;
High-temperature properties of building materials and furnishings, including insulation and structural materials; and
The structural interactions that occur as a result of fires, with particular emphasis on connections between elements such as horizontal and vertical members.
Recommendation 8.17: Old monumental buildings should be given special consideration in two areas:
Inventorying their material properties and structural drawings as a precursor to protective redesign, analysis and recovery, and
Developing fiber-reinforced laminates for increasing the ductility of their masonry.
Recommendation 8.18: Study the more advanced fire-rating practices in Europe, Australia, and New Zealand to assess their applicability to the United States.
Recommendation 8.19: Research should be done to determine the most expeditious means for integrating performance standards with building codes to cover technologies that resist blasts, impacts, and the consequences of fire. This could take a similar form to what was recently employed by the National Earthquake Hazards Reduction Program (NEHRP) in its guidelines for seismic design.
This program should be led by the federal government, perhaps NIST or selected national laboratories. The insurance industry should be a significant participant in this work. The fire and blast tests should be planned and performed under the oversight of the National Fire Protection Association. Objective evaluation of results by independent reviewers is an important step towards facilitating the efficient application of new knowledge and procedures in codes and standards.
Performance standards for dealing with terrorist attack require a probabilistic risk assessment (PRA) approach similar to what has been adopted for earthquake hazards. In simplified terms, risk is the product of the probability of an occurrence times its consequences.
One of the obstacles to developing a risk-based methodology for predicting losses from terrorism is the (thankfully) sparse database of significant events. But in the mid-1960s, when PRA was first developed for seismic risk, the relevant databases and supporting geological knowledge were also much less complete than they are today. However, the idea became very productive once the data were collected. For the moment, an initial resource for terrorism is the databases, maintained by the FBI and ATF, of domestic incidents involving explosives. For example, the FBI Bomb Data Center General Information Bulletin 97-1 catalogs the 1997 domestic bombing incidents with statistics on actual bombings, attempted bombings, explosive bombings, incendiary bombings, and breakdowns by region, state, and target.
It has been suggested, without supporting evidence, that older, heavier buildings may be inherently better able to withstand some types of terrorist attack than modern ones. PRA is an appropriate framework in which to examine this question. Risk modeling can also address the economic implications of alternative design requirements—for example, if resistance to progressive collapse became obligatory for modern lightweight buildings—and it is an appropriate framework for showing the insurance and reinsurance industries how blast engineering mitigates risk.
Recommendation 8.20: Universities and the national laboratories should conduct research on the applicability of a PRA risk-modeling approach for quantifying the expected performance of blast- and fire-resistant designs.
A better understanding of air movements and mixing in HVAC systems could lead to improved designs for lowering vulnerability to toxins.
Recommendation 8.21: Research is needed to determine how different toxins might be distributed, controlled, or filtered by buildings’ air handling and circulation systems. This work will lead to improved techniques for reducing the potential exposures of occupants. In the mean time, HEPA filters could be introduced where space and fan capacity are adequate to replace the simple dust filters currently in use, with the benefit of adding protection from anthrax and other bioterrorism materials.
Under the oversight of the OHS and NIST, this program could be performed by the American Society of Heating, Refrigeration and Air-Conditioning Engineers (ASHRAE), the relevant professional and standard-setting organization.
The exiting of tall buildings under emergency conditions deserves a special note. While the WTC twin towers collapsed with the loss of thousands of lives, the towers actually performed well in that occupants below the floors impacted by the airplanes were provided enough time, after the impacts and before the collapse, to exit the buildings safely. Occupants above the points of impact were not so fortunate because the impact and blast destroyed the stairwells for the multiple floors over which the impact occurred and egress from the upper floors was cut off. It would be appropriate to review emergency egress and related communications systems requirements for tall buildings in light of the WTC experience. Communication systems that provide information to both occupants and first responders about the location and status of egress routes is an essential element for survival.
Recommendation 8.22: The requirements for emergency egress and communications for tall buildings should be reexamined by the National Fire Protection Association in light of the WTC experience and the results of this reexamination should be used to determine appropriate modifications to building codes and standards.
STADIUMS AND OTHER PLACES FOR LARGE PUBLIC GATHERINGS
Recent information indicates that popular venues such as ballparks, concert halls, and entertainment complexes (Disney World, for example) are at risk. In a broader context, mass rallies of any kind must also be considered potential targets, together with the gathering places of the nation’s intellectual, political, and financial elites and of its most vulnerable citizens—our children in their schools or day-care centers.
Stadiums are vulnerable to structural failure from explosives or aircraft impact; to airborne toxins; and to panic reaction by a crowd. Recent efforts to exclude explosives from sports venues and traditional efforts to exclude hazardous materials from rock concerts both illustrate apparently successful policies. There are no major recorded incidents of bomb attacks on stadiums, and the time-consuming and intrusive screening of attendees appears to be tolerated at present. There are no recorded incidents of attack by aircraft; however, there are many examples of close approaches by aircraft to sports venues (usually as part of the entertainment), so it would clearly be possible to mount such an attack.
The structural hazards would result from destruction of key load-bearing elements, though on the positive side the structural redundancy of these buildings is relatively high. Also, they typically contain few materials, such as carpets and furniture, that feed hot fires in enclosed buildings; on the other hand, their expanses of plastic seating would be a source of fuel. Fabric and hard-roof domes of sports stadiums may be tempting targets for a well-informed attack that destabilizes the self-equilibrating forces in the tendons and ring beams that support the roofs. In most instances, however, these supporting members would not be readily accessible to saboteurs (though they are vulnerable to aircraft impact).
Toxic chemicals and biohazards present similar threats to stadium crowds as to crowds in subways and other confined spaces: A lot of people are concentrated in a small area, making them vulnerable even to a highly localized attack. Terrorists willing to expose themselves to lethal doses could effectively spread chemical and biological toxins in these close quarters by hand. Dispersal patterns by HVAC would vary according to the types of agents involved, making the extent of their impact on the occupants difficult to predict. Biological, chemical, and radiological agents that could be employed are covered in Chapters 2, 3 and 4.
Panic also appears to be a significant hazard for crowds, sometimes even greater than that of the agent itself. Whether the cause is real or imagined, people reacting under panicked conditions could, for example, overwhelm exiting systems designed for normal (and relatively modest) flows, thereby causing many injuries and possible deaths. Panic and other intangible impacts on people are addressed in Chapter 9.
Schools and day-care centers deserve attention not because of the numbers of people typically present there but because harm done to them would so deeply affect the rest of us. Schools have evacuation plans for certain conditions and lockdown plans for others, which teachers and students regularly practice. But given that the typical buildings in which these activities are housed enjoy little or no hardening, not much could be done to defeat a direct attack of any significance—as was seen in the attack on Oklahoma City’s Murrah Building, which contained a day-care center. A greater likelihood of threat for schools and day-care centers comes from the secondary effects of an attack on some nearby
location, as was the case in New York on 9/11. Here again, established plans and well-practiced teachers and students minimized the harm that came to the children. The best defense is to be prepared.
Implementation of Existing Technology
The reaction of stadiums to the impact of an aircraft or to explosions from any source needs to be better understood. In addition, in so far as current technology and the designs of current facilities allow, vulnerability to chemical and biological attacks should be minimized. NIST might do this work with universities and the national laboratories.
Recommendation 8.23: Analytical studies, like those performed for earthquake hazard assessments, should be conducted to evaluate the effects of explosions and aircraft impacts on covered stadiums. Each major stadium (and its roof system) in the country should be analyzed.
Recommendation 8.24: Conduct analyses of how different toxins might be distributed, controlled, or filtered by the air-handling and circulation systems of stadiums, as well as of other places where large public gatherings occur, and make the resulting information widely available, particularly for commercial purposes.
Once there is evidence of an attack, adequate provisions for egress must be available. Unfortunately, the egress built into stadiums and similar facilities currently in use do not consider any kind of terrorist attack or the panicked exodus of a large crowd. But crowd management can be improved by physical or structural amenities and by training and preparation. Improved exits, modified barriers that mitigate injuries, signage, and other modifications to the existing requirements for moving people out of crowded and enclosed spaces should be available to local authorities. Such improvements can also have salutary effects on attendees’ attitudes—and on their behavior in the event of a crisis. For example, the highly publicized security at the 2002 Super Bowl reassured attendees, so that even if there had been an incident, attendees would probably not have acted irrationally. As noted in Chapter 9, psychology and social science resources can be brought to bear on efforts to develop more effective methods of crowd management.
Research and Development Priorities and Strategies
We must be able to monitor the air circulating in stadiums for dangerous toxins, but reasonable means are not available for detection of the wide variety of potential chemical and biological agents. Therefore sensors to detect toxins,
similar to and perhaps the same as those recommended elsewhere in this chapter for major buildings and for first responders, need to be developed and deployed. They could be used in conjunction with the control of HVAC systems. Testing and evaluation of airborne-material circulation and distribution by the HVAC systems unique to each enclosed stadium (including on-site testing of simulated aerosol releases) would aid in reducing the impacts of released toxic agents. This is a matter for local building departments, acting on technical advice provided at the federal level.
Recommendation 8.25: Research and development should be directed to creating a special-purpose sensor and supporting system (with its own appropriate set of sampling, calibration, and verification databases) to allow air-handling systems to quickly and reliably determine if the air supply in a building (or a subway or other occupied confined space) is safe or not safe and to adjust the HVAC controls accordingly—for example, contain the dangerous toxins in the area of the building where first recognized, or exhaust the tainted air. (The same sensors and systems recommended in the section above on emergency management and emergency operations centers could apply here.)
In the longer term (5 to 10 years), guidelines should be developed that include assessments of vulnerability to terrorist attacks as a component of the plans for any new large facility for public gatherings. One challenge is to integrate operational and structural practices that achieve strong resistance to terrorist threats while minimizing constraints on the public. Operational practices should include effective crowd-screening technology that enjoys public acceptance. And coordination between owner-operators and structural designers may improve the balance between needed crowd surveillance and built-in structural hardness.
For example, alternative HVAC systems for stadiums should be reviewed to determine whether it is possible to use the systems themselves to reduce risk. If a system is capable of being zoned, to cite one possibility, this could moderate or even prevent much of the toxins’ transport throughout the space.
In any case, it is essential that the egress of people under crisis conditions be achieved in a safe and orderly fashion.
Recommendation 8.26: Undertake research to identify improved methods of egress for large numbers of people from crowded enclosures under conditions of perceived threat. Examine the most reasonable numbers and capacities of egress points, subject to constraints on the function and structure of the buildings, to accommodate a crowd exiting in a state of fear.
UNDERGROUND FACILITIES, INCLUDING TUNNELS
Developed underground spaces include many tunnels, pipelines, basements, and underground parking garages that quietly serve their cities. These unseen and unnoticed assets may also present excellent opportunities for terrorists. Explosive, flammable, or toxic materials could be brought surreptitiously into the city, placed there, and detonated, largely employing the underground environment alone. Awareness should be the first step in limiting this vulnerability because it can point to the need for surveillance, prevention, and detection of potentially harmful activities in these spaces, thereby limiting exposures. However, several particular concerns that require broader responses would still remain.
Many of our major cities have grown up around railroad lines. Over time, however, the need to separate the railroad’s activities from the evolving city became apparent. As a result, urban railroad lines can be found today in tunnels or along narrow or depressed rights-of-way. Thus they are largely out of sight. Meanwhile, railroads routinely carry all kinds of freight—including toxic chemicals, petroleum products, agricultural supplies, and other materials—that could serve the purposes of terrorists. The U.S. Conference of Mayors has expressed concern about this situation (USCOM, 2001). The risk is greatest for sites above or adjacent to the railroad—such as a stadium or concert hall—that are regularly occupied by great numbers of people.
Some major cities, which have grown up adjacent to large bodies of water, are especially vulnerable to the rapid flooding of their tunnels. Where those tunnels are used for passenger railroad or transit services, significant loss of life could result.
Every city utilizes sewers buried under its streets to convey wastewater and storm water to remote sites for treatment and safe disposal. These sewers typically do not flow full—rather, the water is conveyed by gravity in open-channel flow. Thus, should a volatile liquid be dumped into such a sewer and allowed to flow through it and mix with the air present, an explosive mixture could result. If ignited, a section of sewer might then erupt violently, lifting the street, damaging buildings and nearby tunnels for other utilities, and killing or injuring people.
Underground parking for large urban buildings is the rule rather than the exception today; for one thing, development approvals typically require the availability of off-street parking. But as we learned in the 1993 bombing at the World Trade Center, these under-building parking areas are also desirable locations for terrorist attack. A well-placed bomb could cause much damage to the building’s
supporting structure, to its mechanical, electrical, and communications systems, and result in large numbers of occupant deaths and injuries.
Implementation of Existing Technology
Vulnerability to Railcar and Container Contents
Inspections could be increased, perhaps at their points of origin, provided that more personnel are made available and that shippers accept the additional delays. Overall, however, current technology and systems are not adequate to meet this threat. This topic is covered in more detail in Chapter 7, “Transportation Systems.”
Flooding of Urban Tunnels
Urban transit and railroad tunnels that are below the levels of nearby bodies of water are vulnerable to flooding if breached.
Recommendation 8.27: Local authorities should identify and harden sites favorable to the breaching of transit or railroad tunnels that lie below surrounding water levels, and they should increase surveillance of all activities occurring in such areas.
Recommendation 8.28: Once sites are identified, authorities should analyze them to determine their resistance to the effects of explosives detonated either inside or outside the tunnel.
The vulnerability of underground parking areas could be reduced by limiting the size and carrying capacity of vehicles allowed entry and by making the inspection of suspicious vehicles or containers routine. Although this approach requires that trained personnel be posted at entrances and is thus expensive (to cover training, salaries, and around-the-clock staffing), parking fees could be adjusted to account for the added cost.
Tunnel Ventilation Systems
Both highway and transit systems tunnels serving cities require extensive tunnel ventilation systems for safe operation. The highway tunnel ventilation systems are designed to remove vehicle exhaust fumes from the tunnels and also to respond to a fire or explosion in the tunnel by isolating the affected zone, thus allowing occupants not involved in the event to exit safely. Transit tunnel ventilation systems are primarily designed to perform the isolation function. Terror-
ists could disable or destroy these ventilation systems, rendering the underground spaces unsafe to use. They could also employ the ventilation systems to distribute toxins throughout the underground spaces served. Conversely, as discussed above for building ventilation systems, the systems could also be used by the owners to contain or remove a toxin released in the underground space.
Recommendation 8.29: Terrorist threats to the ventilation systems used in occupied underground space and highway and transit tunnels and ways to mitigate those threats should be researched by the National Fire Protection Association and the Department of Transportation. Guidelines for action should then be provided to the owners and operators of these systems.
The threat of exploding sewers could be reduced if local authorities establish tighter controls on access (including installation of locking manhole covers); monitor the air inside sewers for the detection of flammable volatiles; and install barriers of grating in the larger sewers to prevent movement of vehicles or other large objects.
Research and Development Strategies and Priorities
Vulnerability to Railcar and Container Contents
An approach for reducing the probability of explosives or toxins being delivered into cities by railcar would be to use improved and universally required intelligent information units (IUs)—transducers, perhaps—for every railcar allowed to move on urban tracks. Base units that load and read the IUs could be developed as part of the same undertaking and made available to all need-to-know parties. At the point of origin, each IU would be loaded with information about the specified contents, origin, sender, receiver, destination, route, and schedule and then sealed by the local transportation authority. The IUs would be readable by local base units as the train approaches a city. Anomalies would bring the train to a halt until the uncertainties are corrected or the questionable car is cut out of the train and moved to a safe siding. It is hoped that the railroads will see ancillary economic benefits to such an IU-based system—possibly for freight-movement management, contents control, rate setting, and other business purposes.
Recommendation 8.30: Research and development should be undertaken to produce improved intelligent information units (IUs) for installation on every railcar, along with operating systems and coded base units (which could load and read the IUs) for every city. The IUs would need to be hardened to radio-frequency wave interference.
Recommendation 8.31: Policies should be developed that allow only railcars with the IUs mounted and operating to move on tracks that pass through urban areas.
Implementation of this recommendation would require the participation of DOT, the national laboratories, the railroads, and the cities and the Conference of Mayors, and should be coordinated by OHS.
Flooding of Urban Tunnels
With the capability to quickly isolate vulnerable sections from the rest of the tunnel system, the flooding of urban tunnels could be mitigated. Such technology could also be used to isolate sections of the tunnels so that smoke, gases or other dangerous mixtures released there could not infiltrate other sections.
Recommendation 8.32: Rapidly deployable tunnel barriers should be developed and produced, and they should be installed at appropriate locations in transit and railroad system tunnels, so that they will deploy—automatically or on signal—to block the flow of floodwaters in the tunnels.
This should be a DOT/TRB research area, with strong support to be expected from the cities and the transit properties and railroad systems that have such vulnerabilities.
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