Way

A way is an ordered list of nodes which normally also has at least one tag or is included within a Relation. A way can have between 2 and 2,000 nodes. A way can be open for 'closed'. A close way is one where the last node on the way is also the first which may be interpreted as a closed-polyline or an Area or both.

Types of way

Open polyline

An open polyline is way describing a linear feature which does not share a first and last node. Many roads, streams and railway lines are open polylines.

Closed polyline

A closed polyline is a way where where the last node of the way is shared with the first node with suitable tagging. A closed way that also has a area=yes tag should be interpreted as an area.

The following closed way would be interpreted as closed polylines:

• highway=* Closed ways are used to define roundabouts and circular walks
• barrier=* Closed ways are used to define barriers, such as hedges and walls, that go completely round a property.

Area

Main article: Area

An Area (also polygon) is an enclosed filled area of territory defined as a closed way. Most closed ways are considered to be areas even without an area=yes tag (see above for some exceptions). Examples of areas defined as closed ways include:

• leisure=park to define the perimeter of a park
• amenity=school to define the outline of a school

For tags which can be used to define closed poly-lines it is necessary to also add an area=yes if an area is desired. Examples include:

• highway=pedestrian + area=yes to define a pedestrian square or plaza.

Areas can also be described using one or more ways which are associated with a relation:multipolygon relation.

Combined Closed-polyline and Area

It is possible for a closed way to be tagged in a way that it should be interpreted both as a closed-polylines and also as an area.

For example a roundabout surrounding a grassy area might be tagged highway=primary + junction=roundabout + landuse=grass.

Examples

Street as a vector

An ordinary street tagged as highway=unclassified name=Clipstone Street oneway=yes

  <way id="5090250" visible="true" timestamp="2009-01-19T19:07:25Z" version="8" changeset="816806" user="Blumpsy" uid="64226">
    <nd ref="822403"/>
    <nd ref="21533912"/>
    <nd ref="821601"/>
    <nd ref="21533910"/>
    <nd ref="135791608"/>
    <nd ref="333725784"/>
    <nd ref="333725781"/>
    <nd ref="333725774"/>
    <nd ref="333725776"/>
    <nd ref="823771"/>
    <tag k="highway" v="unclassified"/>
    <tag k="name" v="Clipstone Street"/>
    <tag k="oneway" v="yes"/>
  </way>