WASHINGTON: Early on March 4, 1996, a train derailed in the small Wisconsin town of Weyauwega. The toppled cars held a 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 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 United States 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 desperate 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 the off-ramps.

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 World” broadcast in 1938, the fictional presentation that prompted thousands of 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 in fear of Hurricane Floyd — at least one million more than authorities intended. Mammoth traffic jams clogged the freeways. Motorists were stuck on bumper-to-bumper Interstates for 10 hours, to complete a drive to safety that would normally take two to three hours. The largest evacuation in US history, it is now 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 news 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, he said, is whether or not it will 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 flu 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 National Mall, prompting officials to evacuate three federal buildings. After two days, Dwight Watson gave himself up, but not before editorial 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 nearby 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 programme 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, back-up 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.—Dawn/The LAT-WP News Service (c) The Washington Post.