Junction (traffic)

A junction, when discussed in the context of transport, is a location where traffic can change between different routes, directions, or sometimes modes, of travel.

Chicago Transit Authority signal tower 18 guides elevated Chicago 'L' north and southbound Purple and Brown lines intersecting with east and westbound Pink and Green lines and the looping Orange line above the Wells and Lake street intersection in the loop.

Historically, many cities and market towns developed wherever there was a junction. A road intersection offered opportunities for rest or trade for travellers and merchants. Towns sprang up to accommodate this; the first such in Europe were probably at intersections of the Roman roads.

A similar effect came with the growth of rail transport; so-called railway towns grew up near major railway junctions - originally to accommodate railway workers, but expanding into fully functioning settlements over time.

Junctions also developed where different modes of transport intersected, e.g. canal and rail.