Junction (road)

A road junction is a location where vehicular traffic going in different directions can proceed in a controlled manner designed to minimize accidents. In some cases, vehicles can change between different routes or directions of travel.

Origins

Roads were initially built as rights of way to link locations of interest: towns, forts and geographic features like fords. As a result, many such locations formed the meeting point of such roads and they became the first road junctions. Where roads met outside of town, these junctions provided an attractive point to build a new settlement, such that they could receive passing trade from both directions. Scotch Corner is an example of such a location.

Junction names

In the United Kingdom and other countries there is a practice of giving names to junctions to help travellers find their way. On older rights of way it was often the practice for a pub to be located at the intersection to maximise passing trade, and the junction has since become known by the name of the pub (even in cases where the pub has since been demolished). Other junctions may be named after local natural or man-made features.

Modern junctions

However, with the 20th century advent of road traffic, roads became much busier and junctions became clogged with vehicles unable to cross each other's paths. In modern practice, bypasses and ring roads are used to keep through traffic "out" of major population centres.

Intersection versus interchange

There are two different types of junction between roads.
*Interchanges are junctions where roads pass above or below one another, preventing a single point of conflict by utilising grade separation and slip roads. The terms "motorway junction" and "highway junction" typically refer to this layout.
*Intersections do not use grade separation (they are at-grade) and roads cross directly.

References