AIR TRAVEL PROJECTED TO BE FASTEST GROWING MODE OF TRANSPORTATIoN (4-6%yr) DRIVEN BY POPULATION AND GDP GROWTH AND AVAILABLE DAILY TRAVEL TIME automobiles Buses Railways □ Aircraft 1960 1990 2020 55×1012RPK23×1012RPK 54×1012RPK 105×1012RPK @2003 Waitz Source: Schafer et al. (1998), GDPlcap growth rates from IPCC IS92a ScenarioAIR TRAVEL PROJECTED TO BE FASTEST GROWING MODE OF TRANSPORTATION (4-6%/yr) - DRIVEN BY POPULATION AND GDP GROWTH, AND AVAILABLE DAILY TRAVEL TIME - Automobiles Buses Railways Aircraft 1960 1990 2020 2050 5.5 ×1012 RPK 23 ×1012 RPK 54 ×1012 RPK 105 ×1012 RPK Source: Schafer et al. (1998), GDP/cap growth rates from IPCC IS92a Scenario © 2003 Waitz 8