Johns Hopkins Gazette: December 9, 1996 Form

On Research:
Siting Science Uses
Math To Pick

Phil Sneiderman
News and Information
Where should fire stations be located to make sure engines can respond anywhere in the city within 10 minutes? What's the lowest number of fire stations needed to provide this level of coverage? And if the nearest fire crew is occupied, how soon could a backup engine arrive?

For more than a quarter of a century, Charles ReVelle has wrestled with questions such as these. ReVelle a professor of geography and environmental engineering, is one of the founders of a young discipline called location science. Instead of relying on guesswork or playing politics, ReVelle uses complex mathematics and powerful computers to propose locations for important public facilities.

Sometimes, his research finds a flaw in traditional emergency planning practices. For example, city ambulances are often housed at fire stations because local leaders believe it is convenient and economical. But by studying operating costs and constructing mathematical models, ReVelle found that cities could improve their ambulance coverage by basing the vehicles without regard to where fire stations are located. ReVelle and one of his students are using this same approach to decide where a region's medical rescue helicopters should be located to provide the fastest aid to the most residents.

ReVelle's tools can also be applied to decisions on where a broad array of public and private activities, emissions inspection stations, pipelines and even landfills should be located. "My thrust is to recognize problems that need to be solved and to create the mathematics to solve them efficiently," he says.

In recognition of his groundbreaking work, ReVelle was one of two scholars who recently received the first Lifetime Achievement Awards presented by the Section on Location Analysis of the Institute for Operations Research and the Management Sciences.

ReVelle and Richard Francis of the University of Florida were lauded for their contributions to "the development of location analysis as a field of both theoretical and applied research."

ReVelle was cited for a prolific output of material. The Hopkins professor has written or co-authored more than 150 scholarly articles and six books, with another two volumes in the works.

His interest in location science dates back three decades to his days as an environmental engineering graduate student at Cornell University. There, ReVelle first tackled public policy questions by using a branch of mathematics called optimization or linear programming. In his doctoral thesis, he proposed ways to control the spread of tuberculosis within large populations. Later, he drew up efficient and equitable plans to allocate water pollution cleanup costs among communities and industries. He also proposed new methods for sizing multi-use reservoirs.

In the 1970s, ReVelle expanded his research into siting issues. He proposed the best places to open health clinics, libraries, industrial plants and warehouses. As computers became more powerful, he explored more intricate problems involving fire equipment and ambulances. He factored in the different response times demanded of engine companies, which pump water and extinguish the flames, and truck companies, which carry ladders and rescue people from burning buildings. ReVelle considered how traffic congestion could affect an ambulance's arrival time and the need for a backup response when the nearest emergency crew is unavailable.

"These problems have grown in sophistication over the years," ReVelle says. "Here's the most complicated question we've solved: Where should the ambulances be sited, so that the maximum number of calls will have a response within the time standard on 95 percent of the occasions in which the ambulance is called."

When he's not studying emergency calls, ReVelle tries to crack other public planning puzzles. He and his students have plotted hazardous waste transportation routes that avoid population centers. They have shown how to design compact, cost-efficient nature preserves that allow the greatest number of plant and animal species to thrive. They have also figured out how to harvest timber without destroying the forest's wildlife habitat.

In the mid-1960s, ReVelle was one of a handful of researchers involved in location science. Today, the field boasts hundreds of active researchers from disciplines as diverse as economics, electrical engineering and urban planning. The competition for research grants has become intense, ReVelle says, yet location scientists still have a tough time influencing public policy. Partly, this is because skilled location analysts often lack the time, talent or will to "sell" their findings to government officials, he says.

City officials in Baltimore have drawn on ReVelle's expertise while grappling with key emergency service issues. In the mid-1970s, Revelle was part of a Johns Hopkins team hired by the city to determine whether Baltimore could provide effective fire protection with fewer fire stations. In the early 1980s, when Northeast Baltimore residents complained that city ambulances were not responding quickly enough in their neighborhoods, local officials enlisted Revelle and another Hopkins faculty member to evaluate the quality of the deployment of Baltimore ambulance crews.

Nevertheless, ReVelle is pleased that the discipline he helped launch remains vital. "I am very gratified," he says. "I'm glad to be working in this field. I can't let it go. It's too much fun to let go."

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