Early on March 4, 1996, a train derailed in the small Wisconsin town of Weyauwega. The toppled cars held 1 million pounds of liquid propane, some of which erupted, forming a plumed inferno visible for miles. Officials decided to evacuate all 2,300 residents.
Most people were told they would be gone for only a few hours. Authorities turned off electricity and gas to prevent an accidental explosion. With temperatures in the teens, emergency crews began siphoning off the gas, burning it slowly in a nearby pit to avoid further accidents.
The ordeal ended 18 days later, when residents returned to their homes.
Now, as the nation faces the threat of terrorism and major cities contemplate the prospect of mass evacuation, public officials are reviewing Weyauwega and other disasters -- including hurricanes and nuclear plant accidents -- for clues on how best to empty a city.
Complications run the gamut from schools overrun with panicked parents desperate to reunite with their children to freeways clogged by frantic drivers who hit the road even if officials tell them to stay put, a concept known as "sheltering in place."
There are issues about pets -- most owners won't leave them, and most Red Cross shelters won't take them. And the prospect of turf battles between jurisdictions looms -- last year, Mississippi refused to let New Orleans residents fleeing from a hurricane use all four lanes out of Louisiana, citing lack of funds for personnel to staff all of the offramps.
The biggest logistical headache for emergency planners is too many people taking to the roads too quickly.
On the eve of major preparedness drills in Chicago and Seattle, some officials worry about a panic along the lines of Orson Welles' "War of the Worlds" broadcast in 1938, the fictional presentation that prompted some Americans to jump in their cars and flee in the belief there had been an alien invasion.
In Florida in 1999, 2.5 million people hit the highways to escape Hurricane Floyd -- at least 1 million more than authorities expected. Mammoth traffic jams ensued. For 10 hours, motorists were bumper-to-bumper on interstates for a drive that normally takes two to three hours. The largest evacuation in U.S. history, it is a case study at Harvard's Kennedy School of Government called "Safe But Annoyed."
The problems of evacuation devolve to balancing the options -- which course will save the most people?
One of the experts on the issue is Craig Fugate, director of Florida's emergency management services. His review of the options is sobering.
If authorities learn that terrorists are about to unleash a nuclear device, he asks, should they order a large-scale evacuation? Can people be evacuated before the device goes off? If terrorists learn of the evacuation through the media, will they set off the device early? Which would be better, trying to apprehend the bad guys or evacuate the good guys?
The larger question about evacuation that must be asked, Fugate said, is whether it would help.
"The whole purpose is to move people away from danger," he said. "When you look at chemical or biological threats, what are you going to evacuate for? If a [virus] has been distributed, the best thing may be sheltering in place."
In March, on the eve of war with Iraq, a lone tobacco farmer from North Carolina drove his tractor into a pond near Washington's Mall, prompting officials to evacuate three federal buildings, close off traffic for eight blocks, including the main thoroughfare of Constitution Avenue.
After two days, Dwight Watson gave himself up, but not before columnists had time to ponder the troubling implications of one man on a John Deere tying up traffic for days in a city that was preparing for war.
The incident highlighted the challenge to the nation's capital, which, since the Sept. 11 attacks, has worked to become a model for emergency planning. Armed with $156 million in federal funds, coordinating with the governors of Virginia and Maryland, the District of Columbia government has muscled up one of the most aggressive disaster preparedness plans in the country.
"It was clear on 9/11 that our emergency preparedness plan was no more than a three-ring binder on a shelf," said Tony Bullock, the mayor's press secretary. "Literally two weeks later, we embarked on a very serious program to upgrade.... We've gone from a 1970s-style booklet for hurricanes to a sophisticated capability."
Now there are no-notice drills for health and law enforcement officials, backup communications systems and brochures for the public in seven languages, including Braille. In the event of an emergency, traffic lights are to be synchronized between Washington and its feeder suburbs in Virginia and Maryland. The city has installed 750 signs showing motorists the way out.
Perhaps the greatest foil in all evacuation plans comes down to children. If parents are instructed to head north while their children are at a school to the south, will they obey a police officer's order?
If schools decide to shelter in place, will parents pound on the door demanding to get their kids -- forcing the school to open, potentially endangering all the children?
Adam Clipper teaches at Marie H. Reed Elementary School in Washington. He remembers that many parents came to pick up their children after the Pentagon was attacked on Sept. 11, and he anticipates that "a significant number will attempt to enter the school" in the event of a terrorist attack, even if authorities order school administrators to lock the doors.
Another vexing problem is what to do with pets in an emergency. According to the Humane Society of the United States, 7 out of every 10 households have pets.
"I've seen people driving home in danger, eyes streaming, to save pets," Fugate said. "So if we don't provide for pet care, people will put their lives at risk."
The Weyauwega evacuation taught officials a useful lesson about pets: Most owners consider them family.
Weyauwega residents protested the restricted access that left their pets stranded. After the news media reported on the protests, authorities were besieged with calls from angry animal lovers around the country offering to come to Weyauwega to care for the little ones. The governor, after receiving death threats, called out the National Guard. On the fourth day, residents donned helmets and bulletproof vests, climbed into armored carriers and rescued their animals.
Florida sets up alternate shelters for animals, Fugate said, and "we get more volunteers to run a pet shelter than we do for the people shelters." And the Humane Society is negotiating with the Red Cross in hopes of securing shelters for dogs and cats.
Raymond Sandor, who lives north of New York City, found carriers for his pets from a vendor in the former Soviet Union -- devices that were made for infants of high-ranking Soviet officials in the event of nuclear, biological or chemical war. "We don't have kids yet, but we have four cats and they are our babies," he said.
Sandor and his wife worry about a nuclear accident; they live near the Indian Point nuclear facility. Some 40 states have nuclear plants or are within 10 miles of a nuclear facility, and all of them have evacuation plans. "The major challenge -- whether it's a 'dirty' bomb or a nuclear plant accident -- is to gain public confidence," said Brian Grimes, a Seattle engineer who worked for 33 years for the U.S. Nuclear Regulatory Commission and now serves as a consultant to the nuclear industry. "If a lot of people hit the road it could complicate efforts to protect people. You have to think about that."
Fugate seemed sanguine, however, about the human instinct to flee.
"At the World Trade Center on Sept. 11, a lot of people walked back home on foot," he said. "People aren't stupid. They move away from hazards.'