|The shape of a highway area.|
|Used on these elements|
|Status: de facto|
|Tools for this tag|
area:highway=* describes the shape, i.e. the two-dimensional outline of the area of a highway, or parts of it. It is used as a form of Micromapping in addition to the routable, linear way tagged as highway=*.
The tag is applied to a way closed as a polygon or to a multipolygon.
History of the tag
The tag was target of the following proposals. Although they were not approved by voting, the tag is increasingly used, despite remaining inconsistencies.
Pedestrian and bicycle areas:
area:highway=*, when used on roads, should cover traffic lanes, bus lanes, and cycle lanes (any detail added to the way corresponding to the area:highway), and should not cover shoulders, parking spaces, and sidewalks.
Differentiation area:highway vs. area=yes on a highway
area:highway=* had been proposed to describe the non-routable, detailed shape of a (typically linear) highway. The tag requires the linear, routable direction of the highway mapped in addition as lines with highway=*.
area=yes on a highway=* describes a routable highway area on which the dedicated traffic can route omnidirectionally, i.e. from any point along the edge to any other. This is typical for pedestrian areas, or service areas where vehicles drive without prescribed lanes. There are strong voices that argue that routing engines should consider those omnidirectional objects in addition to nodes+edges in classical graph theory; thus no linear highway lines would be required within.
The area:highway tag, stemming from two different proposals, has unresolved inconsistencies:
- It remains unclear if the tag should be used for the full shape of the built highway, or split into functional sub-areas.
- It has been suggested that such mapping is comparable to the mapping of the water covered area of a river with riverbank polygons although so far no consistent locally verifiable property to delineate area:highway=* areas comparable to the concept of water cover has been suggested.
- It is disputed under what circumstances mapping a polygon representation of linear roads adds information and under what circumstances this can be considered unnecessarily redundant to the linear highway mapping and a width=* tag and in violation of One feature, one OSM element.
- Some mappers use area:highway=emergency, where they mean to describe road areas that are painted with white hatching that should be avoided in normal traffic flow, but have nothing to do with emergencies.