Most mass evacuations from major disasters in the United States have been carried out primarily by private automobile. But one significant complaint about the evacuation of New Orleans prior to Hurricane Katrina was that up to 20% of the city's population (about 100,000 people) lacked either the financial means or the automobiles required to evacuate. By what other means could an evacuation be carried out?
- Capacity: About 50-60 passengers per bus on a commuter bus/motorcoach. School buses have capacities up around 75 passengers. An evacuation of 100,000 people would require about 1,700 bus trips by coach, or slightly fewer by school bus.
- Speed: Highway speeds
- Accessibility: Universal
- Limitations: Buses would be ideal evacuation vehicles, except for their limited capacity. They can go nearly anywhere and can travel at relatively high speeds. But even with a 48-hour evacuation period, to remove 100,000 people to a location two hours away (four hours round-trip for the bus) would require about 140 unique buses. Greyhound, by comparison, has about 1,950 buses in its fleet.
- Capacity: A 747-400 can hold just over 500 passengers. An evacuation of 100,000 people would require about 200 fully-loaded flights.
- Speed: Considerably faster than alternatives. Properly-staged, a massive airlift could probably evacuate a substantial number of people in a very short period. O'Hare airport served an average of about 60,000 passengers a day in July 2005.
- Accessibility: Weather conditions in advance of a major storm would be the most significant limiting factor, since most major metropolitan areas have jet-ready airports.
- Limitations: A massive airlift would require a sophisticated and well-coordinated organizational plan. The fuel and maintenance requirements would likely be much greater than most airports could be rapidly equipped to handle, so much of that burden would have to be shifted to the destination airports.
- Capacity: About 100 passengers per intercity rail car with 10-15 cars per train, or 1000-1500 passengers per train total (the high-speed Acela carries 304 passengers, but slower trains can carry more). An evacuation of 100,000 people would probably require 70-80 trains.
- Speed: Heavily dependent upon local conditions. Could probably assume that in an emergency,
- Accessibility: Most urban centers have rail access
- Limitations: The quality of rail service -- especially passenger rail -- varies greatly across the country. While the tracks themselves exist, the number of required locomotives and passenger cars probably exceeds the entire passenger rail fleet already in service in the United States.
- Capacity: The largest cruise ships have a capacity of over 4,300 passengers. Assuming that in an emergency that capacity could temporarily be tripled (by using extra berths and converting public spaces to sleeping use), an evacuation of 100,000 people would require the equivalent of nine or ten massive cruise ships.
- Speed: Even fast ships of this size can only travel in the 20-30 mph range
- Accessibility: Only useful for evacuation sites with deep-water ports
- Limitations: Keeping a fleet of large, empty ships for occasional extraordinary use would be very expensive. The US Navy presently keeps up just two hospital ships, each of which has about 1,000 hospital beds and can only travel at about 20 mph. Both ships are converted supertankers.