Despite the huge loss of life and the massive damage caused by the destruction of the twin towers of the World Trade Center on Sept. 11, the utility systems beneath the buildings "held up remarkably well," a Cornell University engineer with wide experience in investigating disasters reports.
Indeed, says Thomas O'Rourke, damage to the gas, steam, electrical, potable water and waste water systems was largely confined to the immediate vicinity of ground zero where the towers collapsed.
In particular, says O'Rourke, the Thomas R. Briggs Professor of Civil and Environmental Engineering at Cornell, New York City's electrical network was able to operate in an "extraordinarily resilient" way after the disaster, despite the loss of two electrical substations near the World Trade Center. "In many other cities, the way the electrical systems are configured would have resulted in a cascade effect as one substation shut down the next. But in New York City there is a system of local networks allowing one network to operate independently of another," he says. "The rapid restoration of electric power after the event owes much to the commitment and skill of utility crews."
These and other findings from an ongoing study of the infrastructure below the World Trade Center will be reported by O'Rourke at a National Science Foundation (NSF) workshop at New York University (King Juan Carlos Center, 53 Washington Square South) on Dec. 12 and 13.
The workshop, "Learning from Urban Disasters," is organized for the NSF by the Institute for Civil Infrastructure Systems (ICIS) at NYU, of which Cornell is a member and O'Rourke is co-chair of the executive committee. He also is a member of the executive committee of the NSF-Supported Multidisciplinary Center on Earthquake Engineering Research. O'Rourke and Arthur Lembo, a senior research associate at Cornell, have been studying the infrastructure effects of the Sept. 11 destruction for ICIS and have applied for a NSF grant to further their research into understanding "how critical utility systems interact in extreme events," in O'Rourke's words.
In interviews with utility managers over the past few weeks, the two Cornell researchers have started to collect information on the complex network of lines and pipes that intersected under the Trade Center. "We are trying to apply the data from the World Trade Center destruction on a more global, or generic basis," says O'Rourke. "We can treat this as perhaps the most severe case of intense, localized damage we have seen and use it to benchmark the performance of underground infrastructure. We can also compare utility response during September 11 with the distributed damage and behavior of utility systems after natural disasters, such as earthquakes. Such comparisons will improve planning and management for future extreme events."
The researchers report that the damage to the gas, water and electrical systems was confined largely to two-to-three blocks around the collapse. In the case of the water pipe ruptures, the damage was confined to about two blocks from ground zero. Damage to the gas lines, says O'Rourke, "was remarkably well confined and they were able to shut off and isolate the gas system in a relatively short period without incurring collateral fire damage."
Lembo notes that telecommunications were strongly affected, with widespread loss of service immediately after the event. That is because part of the World Trade Center collapsed on the Verizon building, damaging cabling, switching and related equipment.
The two researchers are specialists in compiling geographical information systems (GIS), databases that in city planning, for example, connect physical locations with economic, social and land-use characteristics. O'Rourke and his colleagues have compiled one of the largest GIS databases ever assembled in order to assess the Los Angeles water-supply system's performance during the 1994 Northridge earthquake. He and Lembo plan to use GIS data to evaluate inter-relationships among critical infrastructure systems in New York City.
However, obtaining data will involve gathering highly sensitive information, O'Rourke warns. Some data may disclose system vulnerabilities and must be secure from disclosure to potential terrorists. "We are in uncharted waters here," says O'Rourke. "I'm not only a professor, but also a citizen with responsibilities to government and community. To improve our management of complex systems, we must share information, but we must protect that information from being used for violence and disruption. We need to develop a policy for the beneficial and productive use of information about our critical infrastructure."
Says O'Rourke, ""The lessons from extreme events, like the World Trade Center destruction, can help create more resilient networks of resources and services. We want to take Sept. 11 as an opportunity to examine how all of these systems interacted. We can't afford to take it for granted that the system held up remarkably well. We need to know why."