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Engineering and Homeland Security


A 911 Call to the Engineering Profession

The events of September 11 challenged the future of our heavily engineered environment and the future of the engineering profession.

An attack on our nation . . . thousands dead . . . 20 percent of downtown office space in Manhattan damaged or destroyed . . . more than 40 percent of the subway system capacity to lower Manhattan disrupted . . . economic costs in New York alone of $100 billion. More damage in Washington, D.C., to the symbol of our military prowess. By any measure, the events that occurred on the clear blue-sky day of September 11 were horrific. Unlike many other tragedies, all of these events were of man’s own making. Unlike many past events, both natural and man-made, the events of September 11 were attacks on an "engineered," built environment, a hallmark of our society, which thrives on human proximity, connectivity, interaction, and openness. The very fabric of our "civil" society is tightly woven.

As a New Yorker who grew up and worked in the city throughout my career; as chairman of Parsons Brinckerhoff, New York’s oldest engineering firm whose roots date back to 1885; and as cochair of the infrastructure task force established by the New York City Partnership in the aftermath of the attacks, I believe the 911 call of September 11 presented us with an unusual challenge, as well as an unmatched opportunity. Our response will say a great deal about the future of our heavily engineered environment (our cities), as well as about our profession. We must come to grips with necessary changes in the role of engineers and the needs of an engineered society. We must heed this call.

What lessons can we learn from the attacks of September 11 and their aftermath? What should we teach those who follow in our footsteps? How should we define "critical infrastructure" in the future? These are just a few of the questions we must answer to meet history’s challenge. We must return to the age-old fundamentals of education, namely the 3Rs. But in the highly engineered environment of the twenty-first century, the traditional 3Rs of reading, ‘riting and ‘rithmetic have been replaced by resistance, response, and recovery.

Critical infrastructure must be designed to resist attack and catastrophic failure. Immediately after the attacks and the subsequent collapse of the World Trade Center towers, some of the pundits suggested that high-profile buildings and other critical infrastructure be designed to stop airplanes. Simply put, this is utter nonsense, a disservice to our profession and to society in general. Unless we are prepared to live in an engineered environment that resembles the complex of caves in Afghanistan, we will not design buildings to stop planes. The challenge is to keep airplanes away from buildings and to root out those who challenge our way of life at the source. We must resist the urge to overreact in the short term.

But that does not mean we should not make changes. Every engineering disaster, whether natural or man-made, teaches us something. Sometimes the lessons that lead to a deeper understanding of the real challenges we face are only disseminated to a subset of our profession. Because our profession tends toward specialization, we often have difficulty translating lessons learned to a broad range of disciplines and industry segments. Here is where the NAE could play an important role. The academy could gather information on everything being done, draw lessons from an incident, consolidate this knowledge, and ensure that it is distributed to a wide range of disciplines and industries.

In New York on September 11, we saw the best of engineering, not the failure of engineering. We saw two proud structures swallow two, maliciously guided planes, fully loaded with fuel. The structures not only endured impacts beyond their design basis, but also withstood the ensuing fires; they were not immediately overwhelmed. The buildings were the first of the many heroes that died that day, but only after they had remained standing long enough for as many as 25,000 people to escape. This is the true testament to the designers. In Washington, D.C., we also saw the best of engineering. The Pentagon’s resistance to a large-scale, direct, deliberate assault speaks well of our ability to design critical infrastructure to resist attacks. The successful resistance of the towers and the Pentagon in no way diminishes the human tragedy of that awful day.

As we move forward, we must learn what we can from these tragedies and, as we have in the past, we must incorporate these lessons into future designs. With a comprehensive understanding and broad distribution of these lessons, we can begin to address the larger consequences of the disaster. Not all of the damage was incurred by high-profile buildings in New York and Washington. Damage to surrounding infrastructure--transportation, electricity, and telephone--exceeded (in economic terms) the damage to the buildings. The very purpose of infrastructure--to tie development together--in some ways limits its ability to resist deliberate attack.

The second "R" is response. The attacks left large portions of the transportation, electricity, and telephone networks that service lower Manhattan inoperable and compromised the entire system. In the immediate aftermath of the attacks, transit system operators modified system operation to stop passenger flow into the affected area and remove trains that were already in the area. Their timely actions prevented loss of life to transit passengers and workers, despite the subsequent destruction from falling debris. But then came an even more daunting challenge--to reconfigure the transportation system to meet the needs of the 850 businesses and 125,000 workers who were physically displaced when 25 million square feet of office space was damaged or destroyed and to provide service to the more than 350,000 passengers to lower Manhattan whose commuting patterns were disrupted. Herein lie some of the most valuable lessons for our highly engineered environments.

The first major lesson of September 11 is that infrastructure and development are intricately linked. Although infrastructure is the sine qua non of development and vice versa, we rarely appreciate their interdependencies until we must respond to a new paradigm, such as the aftermath of September 11. Along with the "localized" failure of "development" (the collapse of the World Trade Center towers), there was localized failure of the attendant infrastructures (e.g., a subway line, the local power grid, the PATH station at the World Trade Center, etc.). In response, we reconfigured regional development (an estimated 29,000 employees working outside of New York City and another 29,000 temporarily working out of other space in the city). We also reconfigured our regional transportation network (e.g., mandatory HOV into the city, increased ferry service, increased transit ridership at other river crossings, etc.). Analogous steps were taken for the utility and telecommunications networks

The second lesson of September 11 is that the core capacity of infrastructure systems is essential. By "core capacity" I mean the degree of interconnectivity of the elements of a system, as well as the number of alternative paths available (i.e., a system’s flexibility and redundancy). Sometime before September 11, I attempted to explain the importance of some planned improvements to our transportation system to government officials. I explained that these improvements would enhance the core capacity of a well developed transportation network and would improve overall system reliability, availability, and performance. The benefits of these additions to core capacity would strengthen the overall system and would go well beyond the benefits of adding a new system connection from point A to point B. Unfortunately, my argument for strengthening a complex system in the most complex, engineered urban environment in the world was largely lost. Traditional project evaluation models have focused on the "value" of new connections, ignoring their broader system-wide implications. Improved reliability, availability, and performance from added core capacity to a complex system can pay dividends that are not always apparent.

My argument for improving regional transit systems proved itself in the aftermath of September 11. The core capacity of the affected systems provided the flexibility for dealing with commuting patterns that had to be modified overnight (literally); lines and stations outside the immediately affected area were able to handle passenger volumes exceeding those that a point A to B connection would have achieved. Several days after the attacks, I was gratified to receive a call from these same government officials who now understood the importance of core capacity.

The infrastructure systems impacted by September 11 responded more or less quickly depending on their core capacities and the concentration of critical infrastructure in the damaged area. Older, more mature systems responded better than many newer systems, which were still heavily focused on building new connections and did not yet have as high a level of core capacity. This experience suggests that core capacity should be a criterion in the planning and implementation stages of new infrastructure.

Core capacity is not just the extent of a system or the number of alternative system paths. It is also the intrinsic quality of the system when it comes under stress. This brings us to the third lesson of September 11--deferred maintenance represents a real cost and a real risk.

The history of engineering is marked by exciting breakthroughs, great works of master builders, and outstanding service. Regretfully, it is also marked by the systemic degradation of some of our greatest achievements. Society at large, and even some people in the engineering profession, do not consider sustained maintenance as important as the creation of new projects. For many reasons, we have allowed some of our most complex systems to fall into disrepair thus compromising their level of reliability, availability, and safety. The problem is most apparent in failing rail systems in England and the United States, but deferred maintenance affects every element of infrastructure.

Not too long ago, the New York City transit system was in urgent need of repair and maintenance. Out of that crisis emerged a commitment to fund, reorganize, rebuild, improve, and maintain the system to a well-defined standard. To a large measure, the capability of responding to September 11 was the result of good, timely maintenance. Other elements of infrastructure with higher backlogs of deferred maintenance are struggling to keep up.

The fourth lesson of September 11 is that operational and emergency response training is an integral element of critical infrastructure response. Just as we factor constructability reviews into our design process and maintainability considerations into our construction details, we must include operational training in our engineering of critical infrastructure. The many areas of exceptional performance in response to September 11 underscores the point. The events also revealed the need for new scenarios. We must be prepared to respond to new threats in the form of weapons of mass destruction, higher risks of collateral physical and economic damage, and more extended response times. Training of first responders must be integrated with operational training for infrastructure systems. We must also understand how first responder teams have evolved with our increasingly engineered environment.

The fifth lesson of September 11 is that the first responder team must include engineers and builders in addition to the traditional triad of fire, police, and emergency services. On September 11, the engineering and construction industry voluntarily reached out to provide technical and construction expertise. Although protocols were not firmly in place and this "fourth responder" had not participated in response training, the help of engineers and constructors has been critical.

From now on, response protocols in engineered urban environments must incorporate this "fourth responder," and dedicated training facilities must reflect the unique nature of highly engineered environments and their infrastructures. Legislation must also be passed to remove the risks that accrue to engineer "volunteers" who are not covered by Good Samaritan statutes.

The third "R" is recovery. Building in as much resistance as makes sense from a risk-weighted, operational, and economic perspective enhances our ability to respond. We can provide core capacity, focus on reliability, availability, and performance, and reconfigure inherently resilient systems. But we must also plan for the recovery of the capacity and service that was destroyed. We must be prepared to restore the engineered fabric, making it even better than it was. In other words, we must engineer critical infrastructure for recovery in the following ways:

  • ensuring accessibility to the sites of critical infrastructure
  • ensuring the availability of specialized construction equipment, contracts, and materials
  • developing a well documented system with clear interface points
  • preplanning and rehearsing response and recovery scenarios for high-probability events (e.g., earthquakes, hurricanes, floods)

But, to truly respond, even more will be needed--an effective response also requires a vision. Every aspect of the engineered environment must be understood not only in terms of its past and present, but perhaps more importantly, in terms of its future--how it will evolve; how resistance, response, and recovery can be built into the system as it expands; how it fits into the vision of the future; and what role it plays in the overall engineered environment. Effective recovery can only begin with this vision.

The 3Rs--resistance, response, and recovery--can provide a new framework for engineering our critical infrastructure in the aftermath of September 11. But we must prioritize our efforts in terms of our most critical needs. To put it simply, we must agree on what comprises critical infrastructure. Here, I confess my own predisposition to adopt a broad view of system behavior. In those terms, we can identify the following characteristics of critical infrastructure systems:
  • Rapid failure would lead to a catastrophic loss of life (by rapid I mean relative to the consequences possible as opposed to an absolute time scale).
  • Failure or significant degradation would have unacceptable economic consequences.
  • Rapid failure would significantly undermine rescue and response efforts (e.g., if emergency operations centers were located in proximity to high-profile targets).
  • Significant degradation would significantly interfere with recovery efforts.

Engineers must become the master builders of the twenty-first century. We must be systems thinkers, determined visionaries, and political pragmatists imbued with the ethics and integrity that have made engineering a proud profession. Engineers must design for the 3Rs, as well as for functionality, safety, reliability, maintainability, and sustainability. We cannot be content to play a secondary role in building our future. We must have a voice, and we must take risks. In short, we must be leaders!
About the Author: Robert Prieto is chairman of the board of Parsons Brinckerhoff, Inc.