Junctions

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Logo. Feature : Junctions
One example for Feature : Junctions
Description
Related to junctions between roads
Tags

See Editing Standards and Conventions#Junctions for editing basics.

Road intersections

Simple intersections

A simple intersection is represented by the ways for the two roads sharing a common node.

Dual carriageway intersections

When a single carriageway intersects a dual carriageway (on the same level), the junction is represented by two nodes and a small section of the single carriageway (left image). When two dual carriageways intersect, the junction is represented by four nodes and four small sections (right image).

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When all sections of a carriageway have the same attributes, they can be represented by a single OSM-way going through. Once attributes are different, such as having turn:lanes=* or destination=* mapped, they become split into individual OSM-ways.

Representing a road area by a linear OSM-way is an abstraction for routability. In analogy, the four nodes and the inner way sections of a dual carriageway junction are an abstraction from the real junction area (grey in the example images), also required for routing. This can however lead to problems for assigning the name=* tag. Obviously, the pink segments m and n in the pictures can be named as A-Road without a conflict. On the other hand, the blue segments p and q might be named either B-Road or C-Road, or given no name at all. Similarly, the destination=* should be tagged on the outer segments where things are unambiguous.

Roundabouts

Roundabouts should be tagged as junction=roundabout.
Small roundabouts where the middle can be traversed by vehicles should be tagged as highway=mini_roundabout.

Traffic control

Intersections with stop signs should be tagged highway=stop.
Intersections with traffic signals should be tagged highway=traffic_signals.

Waterway crossing

A ford (where automobiles, pedestrians, or horses enter the water to cross a stream or river) should be tagged as ford=*.

Rail/road level crossings

Rail/road level crossings should be tagged as railway=level_crossing.

Pedestrian road crossings

Pedestrian road crossings (UK:Zebra Crossings; US:Crosswalks) should be tagged as highway=crossing. Pedestrian rail crossings should be tagged railway=crossing.

Proposals

  • highway=junction: Proposal for mapping the extent of junctions and to reduce the number of needed relations