Because of their roles in the global transportation network, airports can help spread diseases by making it easy for infected people to move from state to state or country to country. In a recent study, MIT researchers determined how influential the 40 largest U.S. airports would be in the transmission of contagious diseases originating in their home cities. Kennedy Airport topped the list in terms of contagion influence, followed by airports in Los Angeles, Honolulu, San Francisco, Newark, Chicago (O'Hare) and Washington (Dulles).
Atlanta's Hartsfield-Jackson International Airport, although it serves more passengers with the greatest number of flights, ranked eighth. Why? Because an airport's contagion influence doesn't depend solely on number of passengers but on its strategic position within the global transportation network. For example, the Honolulu Airport, with its location in the Pacific Ocean and its connections to distant hubs, can contribute more significantly to the spread of viruses and bacteria than Atlanta's airport [source: Brehm].
Ground Transportation: Plane Train? Shuttle? Rental Car?
An airport can't exist in isolation. It depends on a massive surface-transportation system so that people can get to and from the airport, park and get from place to place within the airport structure itself. While your first thought about an airport is air travel, ground transportation is pretty crucial, too.
The busiest airport in the world is Atlanta's Hartsfield International Airport. You can take an extensive tour of Atlanta's ground transportation services on the airport's website, but here are some highlights of how ground transportation is critical:
- Roads allow access to and from the airport: In Atlanta, four interstate highways move traffic to and from Hartsfield. There's also a station for MARTA trains, which are part of the city's rapid transit system.
- Parking allows short- and long-term storage of automobiles. Parking can be on or off airport grounds, and some parking systems are run by private vendors under airport regulation. Hartsfield has more than 30,000 public parking spaces for its domestic terminal about 3,500 for its international terminal.
- Passenger drop-off and pickup areas make it easier for passengers to get into the terminals, although they're often plagued by traffic congestion because so many people are trying to get in and out.
- Rental car companies serve airports. Hartsfield has a dedicated rental-car facility with two four-story parking decks and 8,700 parking spaces. The center boasts a 137,000 square-foot service center where arriving passengers can rent vehicles from 13 rental-car companies.
- Shuttle services provide passengers with transportation to local hotels and off-site parking facilities.
- Private transportation is available in the form of limousines, vans and taxis.
- Public transportation (such as municipal buses and subways) may have stations at an airport. Besides the MARTA station at Hartsfield, 12 bus lines (public and private) serve the airport.
- Internal subway trains and trams may be available to help passengers get to the terminal gates from the concourse. Hartsfield's People Mover is a 3.0-mile (5.6-kilometer) loop track. The ATL SkyTrain, an elevated train, also connects passengers to the rental car center, the Georgia International Convention Center and hotels and office buildings.
In many ways, airports act as transportation hubs for entire regions. A person flies, say, from Washington, D.C., to Atlanta. After he arrives, he takes the SkyTrain from the main terminal to the rental car center. He rents a car, then drives downtown for a business meeting. In a little more than two hours, he has completed a trip that would have taken him 9.5 hours in a car. But think of the people, processes and modes of transportation he has engaged to make his quick trip. It's a highly complex system with hundreds, if not thousands, of moving parts and interconnecting strands. Managing all of this, as we'll see next, is a massive undertaking.