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September 2002

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Mapping Disaster: Cartographers Aid Workers at Ground Zero

You don’t often associate the words “heroism” and “cartography.” Yet just hours after the collapse of the World Trade Center buildings last September 11, mapping experts across New York City were working fast to put the dimensions of the disaster down on paper, helping rescue and recovery workers stay safe at the site. They too surely saved lives.

“No one could have imagined the magnitude of this effort,” says Chris Schielein of Environmental Systems Research Institute (ESRI), a company that specializes in geographic information systems (GIS) software, which allows layers of data to be displayed as maps. By September 14, banks of computers running GIS plotters were already humming at Pier 92, an empty terminal on the Hudson River set up as an emergency mapping center.

From there, and from other sites around the city, specialists from city agencies, private firms such as ESRI, and the federal government worked as a team to meld maps of Manhattan with incoming data on the damage. Under high security, their around-the-clock efforts were producing hundreds of maps a day by the end of Pier 92’s first week in operation.

The maps they made provided information on everything from the structural integrity of the World Trade Center’s seawall to places where rescue workers could get cold drinks. They charted the density of the acrid smoke plume and used computer models to track its likely path across the city. Maps of street closings, gas and electric outages, and loss of water and telephone service were updated daily—sometimes every few hours—and distributed to anyone who needed them.

Other mapping technologies also played a vital role. Since air traffic was limited after the disaster, satellite photographs offered immediate aerial views of the devastation in lower Manhattan. Several days later, airplane-mounted light-detection-and-ranging (LIDAR) devices—think speed guns—used their lasers to pierce clouds of smoke and dust and thus locate hidden support structures in wrecked buildings. Additional LIDAR views showed color-coded heights of the damaged structures and the constantly shifting rubble piles. This information helped officials know how tall debris-removal cranes needed to be. A third technology, thermal scans, helped firefighters pinpoint underground fires burning near fuel and Freon tanks.

Even before September 11, New York City had in place an extensive digital base map so detailed it shows home plate at Yankee Stadium. Known as NYCMAP (pronounced NICE-map), it was compiled from some 5,000 aerial photographs. In the disaster’s aftermath, NYCMAP served as a geographic foundation for information critical to Manhattan residents, including damaged-building assessments and access to transportation and other public services.

Other cities—Philadelphia, Seattle, and San Diego, to name a few—have similar mapping projects. “And those that don’t, should,” says Alan Leidner, the director of GIS for New York City’s Department of Information Technology. “Because we were working with an accurate geography of the city, we were able to get up and running very quickly.”

Dave Kehrlein, a California state government GIS expert, was one of many geographers from across the country who traveled to New York last September to help the mapping effort. He hopes that GIS technology gets more national attention—and more government funding.

“Preparation for a terrorist attack is no different than preparation for an earthquake or a flood,” he says. “We have natural disasters often enough in California that we take GIS very seriously. If another attack happens, we know we’re going to be asked to perform.”

Web Links

U.S. Environmental Protection Agency (EPA)
Read the “EPA Response to September 11,” which details the EPA’s efforts to monitor conditions for recovery workers and Lower Manhattan residents.

Environmental Systems Research Institute (ESRI)
This site gives background on ESRI’s geographic information systems software applications.

U.S. National Geodetic Survey
Learn about the National Geodetic Survey’s use of light-detection-and-ranging (LIDAR) technology.

Free World Map

Bliss, Jeffrey. “Hunter College Cartographers Aid Workers at Ground Zero.” CUNY Matters (December 2001). Available online at cuny.edu/events/cunymatters/2001_december/groundzero.html.

Harwood, Susan. “New York City—Creating a Disaster Management GIS on the Fly,” ESRI News—ArcNews (Winter 2001/02). Available online at www.esri.com/news/arcnews/winter0102articles/nyc-creating.html.

“NOAA Conducts More Flights Over World Trade Center Site.” Available online at www.noaanews.noaa.gov/stories/s798.htm.

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