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Riding out the Storm
Professor’s research may save lives during a hurricane
By Melissa Edler,’00
In Palm Beach County Fla., news stations warn of an advancing hurricane. The storm is expansive and moving rapidly toward the coastline. In a small residential neighborhood, a middle-aged man and his elderly mother finally decide to evacuate their home. They pack their few belongings into their small car and drive slowly north on Interstate 95 — with tens of thousands of frantic, like-minded people — until traffic comes to a standstill.
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| Dr. Thomas Schmidlin displays an image of tornado damage he witnessed in the southeastern United States. |
“Hurricane Frances is expected to hit the shoreline within the next hour,” announces a local Geography professor Dr. Thomas Schmidlin displays an image of tornado damage he witnessed in the southeastern United States; “Anyone who is outside or on the road needs to seek shelter as soon as possible.”
The man and his mother need to find somewhere safe to wait out the storm. They won’t have time to get to a shelter. Where can they seek refuge during a hurricane at the last minute? Then the man sees an above-ground, multilevel parking garage near the next exit. Will that protect them?
In 2002, Helene Wetherington, former assistant director of the Palm Beach County, Fla., Division of Emergency Management, attended the National Hurricane Conference where she met Dr. Thomas Schmidlin, a meteorologist and professor of geography at Kent State University. When she heard Schmidlin discussing his research on the stability of passenger vehicles in tornado winds, Wetherington asked for his help with two questions: During a hurricane, are parking garages safe as a “refuge of last resort”? And at what wind speed is it unsafe for emergency vehicles and buses to be on the roads during a hurricane?
During hurricanes, car rental agencies and dealerships commonly use parking garages to shelter vehicles. But Wetherington was hesitant to recommend them as a safe place for the general public without having more information. “There was no research to show parking garages were safer than the side of the highway during a hurricane,” she says.
Schmidlin took a hands-on approach to answer Wetherington’s questions. The first task was to visit a parking garage during a hurricane — no small feat. Along with Barbara Hammer, a former research associate at Kent and Paul King, outreach coordinator from the Boyce Thompson Institute atCornell University, he waited for a hurricane to develop along the southeast coast that would give them ample time to travel and set up. Their chance came in September 2003 when Hurricane Isabel began forming. Two days before the hurricane hit shore, they arrived at a city-owned parking garage in Norfolk, Va., with four computerized anemometers, which measure wind speed, and a data logger, which stores wind speed information during the storm.
Schmidlin was concerned there might be jet streams, or dangerous airflows. “It was very noisy. The wind was roaring and blowing things around,” he says. However, after collecting data for more than 12 hours during the hurricane, the team discovered that winds are very light inside parking garages. While gusts outside reached in excess of 70 mph, only 20 feet into the parking garage the wind speeds were 25 mph or less. At the center of the garage, approximately 100 feet inside, gusts reached 16 mph or less. Winds are strongest at the upwind and downwind openings, and wind speeds increased about 5 percent from one floor to the floor above, according to their findings.
"Winds in a parking garage during a hurricane are unlikely to pose a hazard to vehicles,” says Schmidlin. “A parking garage is a very good place to use as a ‘refuge of last resort.’”
Schmidlin recommends the parking garage meet certain specifications. Look for open-air garages (with no glass windows), he says, because they allow air flow through the building, creating friction that slows wind speed. Stay away from openings where debris might be carried into the garage. Avoid parking on the rooftop, as well as the ground level, where storm surges can flood. Stay inside the vehicle unless there is access to a building.
“Recommending cars pull in parking garages for protection in a hurricane is something we can do to save lives at the last minute,” says Wetherington.
Another risk during a hurricane is the one faced by those trying to save lives —first responders who drive ambulances and city buses, which transport people with special needs. Most counties in Florida pull their emergency vehicles from the roads when winds reach between 39 and 45 mph, which are considered tropical-storm-force winds.
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| Tests in a wind tunnel determined how safe ambulances and busses are in high winds. |
Schmidlin’s previous field work and wind tunnel experiments showed common passenger vehicles are “upset” at winds around 110mph. An upset occurs when the aerodynamic load exceeds the vehicle weight load —in other words, when at least one tire comes off the ground. Schmidlin decided to use wind tunnel tests again to estimate the upset wind speeds at various angles on a Type I ambulance (box), Type II ambulance (van) and a city bus.
The tests were performed in the commercial-grade Beech Memorial Wind Tunnel at Wichita State University in Kansas, with assistance from Scott Miller, professor and chair of the Department of Aerospace Engineering, and Greg Thumann, a doctoral student there. Models of the vehicles were mounted on a rotating pedestal connected to a six-component external balance. Schmidlin and his team measured lift (the amount of wind rolling over the top of the vehicle), drag (the force pushing on a vehicle from the front or back) and side forces, and the pitching, rolling and yawing moments (other influences that slide, rotate or partially lift a vehicle from the ground).
The results: Wind speeds of 135 to 150 mph will upset Type I ambulances (box), while speeds of 140 to170 mph tip Type II ambulances (van). However, city buses tip at much lower wind speeds, between 60 and 75mph.
"Results were much more stable than we had anticipated, and we realized recommendations by our safety department were very conservative,” says Wetherington.
Schmidlin suggests fire departments allow their ambulances to continue handling emergencies until winds reach hurricane force, or 75 mph.
William O’Brien, director of Palm Beach County ’s Division of Emergency Management, says, “Now those who respond first to emergencies have definitive research on which to base their decisions.” He adds, “This type of research needs to be done, and Schmidlin is a great resource for doing it.”
“This was a partnership of academics and practitioners that should be emulated more,” says Wetherington. “Few academics recognize their importance to researchers, and few practitioners reach out to academics.”
Schmidlin agrees. “Geography is a science that is helping society,” he says. “It’s based in theory but can be used in the real world.”
For more information on Schmidlin’s research, contact him at tschmidl@kent.edu.