Dangers to Underground Infrastructure
London has responded effectively to the disruption of services following terrorist bombings July 7, but the event underscores the need for a careful examination of the vulnerabilities of the underground infrastructure of our cities, said a Cornell University engineer.
"I was impressed. The London Stock Exchange never stopped. The way they've cordoned off areas, the business continuity was very good. For such a potentially disruptive event they have done very well in recovering and restoring services," said Thomas O'Rourke, the Thomas R. Briggs Professor of Engineering at Cornell, July 8.
O'Rourke, whose research is aimed at making underground utilities more resistant to damage whether from man-made or natural disasters had just returned from London, where he was the featured speaker at a June 30 meeting convened by the Bank of England to discuss financial sector resilience in the face of disasters. Until recently, O'Rourke said, financial institutions had worried mainly about cybersecurity, but after the World Trade Center attack, they became interested in the external infrastructure networks that support their cyber infrastructure.
In his London talk, O'Rourke described the lessons of 9/11, based on his own research at the site. Communications in New York City were widely disrupted, largely because of damage to the underground infrastructure near the collapsed towers. Broken water mains poured 35,000 gallons of water per minute into a seven-story underground space, filling it "like a big bathtub" and flooding transportation tunnels all the way to New Jersey. Falling debris smashed into a vault beside the Verizon building just north of the Twin Towers, cutting cables. "What wasn't severed was flooded by millions of gallons of water from the broken water mains," O'Rourke told his London audience.
He predicted that in a major disaster, cell phones would not be helpful for emergency communications because of the overload on the system. The prediction was borne out after the London bombings, he found. What does work besides two-way radio communication, he said, is wireless e-mail through portable devices like the Blackberry. Because e-mail is not a continuous flow of data like voice communication, mail routing is more flexible and able to accommodate heavy traffic more easily.Fortunately, the London bombings did not attack underground infrastructure directly. They were aimed at destroying transit vehicles and tying up the transportation system. But the underground utility systems of large cities remain highly vulnerable to damage.
"We have been building for ourselves a more and more complex world and packed our systems below street level with more and more different components often with little planning or integration," O'Rourke pointed out. "These systems have accidents without terrorists. We'd like to make them work better under normal circumstances. Irrespective of terrorism, there's a lot to be gained."
In the Winter Structures Laboratory at Cornell, O'Rourke and Harry Stewart, Cornell professor of computer and electrical engineering, work with lab manager Tim Bond, research associate Mike Palmer, information technology specialist Dave Ash and civil engineering students with massive, computer-controlled hydraulic rams to simulate the effect of earth movements on pipelines and other utility conduits. The lab is part of a chain of testing and research sites called the George E. Brown Jr. Network for Earthquake Engineering Simulation, funded by the National Science Foundation. O'Rourke also is working with Stephen Wicker, Cornell professor of electrical and computer engineering, on ways to distribute remote sensors throughout utility networks to monitor their behavior.
Much underground infrastructure is aging and was not designed to handle extreme stress, he has found. For example, he said about 75 percent of water mains in New York City and Los Angeles are made of brittle cast iron. Newer mains use ductile metals and plastics that have more flexibility.
Another problem, O'Rourke said, is that different utilities are often in close proximity. "You can have a major telecommunications line next to a water main next to a high-voltage electric cable," he said. In 1983, he recalled, a water main broke in the Garment District in New York City, flooding an adjacent electric substation, starting transformer fires that released toxic chemicals. Electricity service in midtown Manhattan was shut down, and along with it the track signaling systems of the subway, paralyzing transit. And all during that week, garment buyers came to town to place their orders for the year. "It cost scores of millions of dollars, all from one 12-inch water line," O'Rourke said.
The problem is aggravated, he said, by the fact that utility companies often don't talk to each another, so workers are not able to locate these dangerous proximities. "We can make them strong where they cross," he said. "Somebody has to know where they are, but organizations are reluctant to disclose this information."
Cornell University College of Engineering: http://www.engineering.cornell.edu.
This article originally appeared in the 07/01/2005 issue of Environmental Protection.