For the purposes of this report, an air-rail connection refers to a connection between an airport terminal and an intercity passenger rail station (in other contexts, an air-rail connection may refer to a connection between an airport terminal and an intracity rail station that serves other forms of local rail, such as commuter rail or a subway system). An air-rail connection facilitates mobility between a rail station and an airport terminal through a variety of modes and methods, such as an airport shuttle, local transit connection, automated people mover or guideway car, or by walking. Depending on the extent of the connectivity, intercity passenger rail can perform three main roles for air passengers.