A road junction is a location where vehicular traffic

Traffic

Traffic on roads may consist of pedestrians, ridden or herded animals, vehicles, streetcars and other conveyances, either singly or together, while using the public way for purposes of travel...

 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

Road

Road

A road is a thoroughfare, route, or way on land between two places, which typically has been paved or otherwise improved to allow travel by some conveyance, including a horse, cart, or motor vehicle. Roads consist of one, or sometimes two, roadways each with one or more lanes and also any...

s were initially built as rights of way to link locations of interest: town

Town

A town is a human settlement larger than a village but smaller than a city. The size a settlement must be in order to be called a "town" varies considerably in different parts of the world, so that, for example, many American "small towns" seem to British people to be no more than villages, while...

s, forts

Fortification

Fortifications are military constructions and buildings designed for defence in warfare and military bases. Humans have constructed defensive works for many thousands of years, in a variety of increasingly complex designs...

 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

Scotch Corner

Scotch Corner is an important junction of the A1 and A66 trunk roads near Richmond, North Yorkshire, England. It has been described as "the modern gateway to Cumbria, the North East and Scotland".-Geography:...

 is an example of such a location.

Junction names

Junctions are often named to help travelers navigate road networks. Names can be assigned by geographic location of the junction, or the name or direction of the connecting routes.

In some cases, particularly in the United Kingdom

United Kingdom

The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...

, a junction could become known by the name of a notable pub

Public house

A public house, informally known as a pub, is a drinking establishment fundamental to the culture of Britain, Ireland, Australia and New Zealand. There are approximately 53,500 public houses in the United Kingdom. This number has been declining every year, so that nearly half of the smaller...

 located at the intersection. Pubs were often located in junctions to maximize passing trade, and the junctions became known by the name of the pubs, even in cases where the pub was later 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

Bypass (road)

A bypass is a road or highway that avoids or "bypasses" a built-up area, town, or village, to let through traffic flow without interference from local traffic, to reduce congestion in the built-up area, and to improve road safety....

 and ring roads are used to keep through traffic out of major population centres.

In some countries that have right-hand traffic, a right turn on red

Right turn on red

Right turn on red, or simply right on red, is a principle of law permitting vehicles at a traffic light showing a red signal to turn right when the way is clear, in a country with right-hand traffic...

 is permitted at traffic lights in order to reduce waiting times. It can be implemented either by allowing the vehicles to turn right by using the give way rule, or by providing a separate lane connecting the two perpendicular roads and avoiding the junction entirely.

Conversely, some countries with left-hand traffic use a left turn on red rule.

Intersection versus interchange

There are two different types of junction between roads.

• Interchanges
  Interchange (road)
  In the field of road transport, an interchange is a road junction that typically uses grade separation, and one or more ramps, to permit traffic on at least one highway to pass through the junction without directly crossing any other traffic stream. It differs from a standard intersection, at which...
  
   are junctions where roads pass above or below one another, preventing a single point of conflict by utilising grade separation
  Grade separation
  Grade separation is the method of aligning a junction of two or more transport axes at different heights so that they will not disrupt the traffic flow on other transit routes when they cross each other. The composition of such transport axes does not have to be uniform; it can consist of a...
  
   and slip roads. The terms motorway junction and highway junction typically refer to this layout.
• Intersections
  Intersection (road)
  An intersection is a road junction where two or more roads either meet or cross at grade . An intersection may be 3-way - a T junction or fork, 4-way - a crossroads, or 5-way or more...
  
   do not use grade separation (they are at-grade
  At-grade intersection
  An at-grade intersection is a junction at which two or more transport axes cross at the same level .-Traffic management:With areas of high or fast traffic, an at-grade intersection normally requires a traffic control device such as a stop sign, traffic light or railway signal to manage conflicting...
  
  ) and roads cross directly. Forms of these junction types include Roundabout
  Roundabout
  A roundabout is the name for a road junction in which traffic moves in one direction around a central island. The word dates from the early 20th century. Roundabouts are common in many countries around the world...
  
  s and traffic circle
  Traffic circle
  A traffic circle or rotary is a type of circular intersection in which traffic must travel in one direction around a central island. In some countries, traffic entering the circle has the right-of-way and drivers in the circle must yield. In many other countries, traffic entering the circle must...
  
  s, priority junctions, and junctions controlled by traffic light
  Traffic light
  Traffic lights, which may also be known as stoplights, traffic lamps, traffic signals, signal lights, robots or semaphore, are signalling devices positioned at road intersections, pedestrian crossings and other locations to control competing flows of traffic...
  
  s or signals.