The amount and growth rate of airport traffic can be influenced by four major factors.
- Demand pattern. The world’s largest airports correspond to the world’s largest cities, particularly in advanced economies with higher income per capita. Aside from basic demographics, the traffic handled by an airport is strongly influenced by core activities such as tourism, business, and high added-value manufacturing. Cities having a strong commercial orientation, such as corporate head offices, experience additional demand for air travel. A similar observation applies to tourism, which is a substantial user of airport facilities. For cities such as Cancun (Mexico), Palma de Mallorca (Spain), or Jeju (South Korea), touristic demand is the main generator of airport activity.
- Network connectivity. The higher the connectivity of the airport, the more air traffic as it offers options to a wider array of destinations. This is particularly the case for airports acting as major hubs for air carriers. For instance, Atlanta is the world’s largest passenger airport mainly because major airlines such as Delta and Southwest use Atlanta as a hub. In this case, each connecting flight generates two movements per passenger as opposed to one without a connecting flight. Connectivity can also be observed in air cargo operations, with hubs such as Memphis and Louisville accounting for the world’s busiest freight airports.
- Competing airports. Most large metropolitan areas have seen a duplication of airports, in part because of the lack of capacity of the main airport but also because other neighboring jurisdictions saw airport development as an opportunity. This competitiveness can even be extended further with the possibility of cross-border alternative airports. Users have more choice and a specialization of regional airports around passengers, cargo, specific destinations, and even airlines (e.g. low-cost carriers) can emerge.
- Physical capacity. The number of runways is one of the most important factors in airport capacity since they limit the number of plane movements that can be accommodated within a time period. When several runways are present, terminal capacity becomes a factor of airport capacity as it imposes limitations on the number of gates available at any given time. Expanding an airport can be challenging as it can be limited by its footprint, which often cannot be expanded beyond the initial allocation. Airports such as Hong Kong and Osaka have been built on an entirely new footprint because the footprint of the prior airports could not be expanded. On existing footprints, runways can be expanded, and new runways can be added. The same applies to terminals, which can be renovated and expanded to handle additional capacity.