Co-location is one form of influence that transportation has on the location of economic activities. In this case, it is the transport terminal such as a port, an airport, a rail station or an intermodal rail yard, that provides a multiplying effect within a co-location zone. This zone is an adjacent area within which it is assumed that the benefits of co-location are derived. Outside this area co-location ceases to play a significant role and is replaced by other location factors such as transport costs (general accessibility).
Co-locational advantages are mainly the outcome of an interdependency between the terminal and the activity since they are their respective customers and jointly benefit from their presence. An office park (including hotels, parking lots, restaurants and convention centers) is a common form of co-location for passenger terminals while a logistics zone is a common form of co-location for freight. They are particularly effective since they combine the advantages of co-location with economies of agglomeration.