Tag:dual_carriageway=yes

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Public-images-osm logo.svg dual_carriageway = yes
Dscf0444 600.jpg
Description
Specifies that a highway is a dual-carriageway road (divided highway) Edit or translate this description.
Group: Highways
Used on these elements
should not be used on nodesmay be used on waysshould not be used on areasshould not be used on relations
Requires
Useful combination
See also
Status: in use

Wikidata

The tag dual_carriageway=yes has been used to specify that a highway is a dual carriageway or divided highway: a road with a dividing strip or barrier between the traffic in opposite directions. The carriageways in each direction may be divided by an open strip, central reservation or median of grass or bare ground, or by a barrier such as a low wall, fence or hedge. Usually there are two or more lanes in each direction. Note that this tag is not used for motorways.

Majority of uses are currently by one user in Krakow, Poland, as of late 2020[1]. A typical dual carriageway is not using this tag.

How to map

Map dual carriageway.png

Add the tag dual_carriageway=yes to a way which is tagged as a highway=primary, highway=secondary or other highway=* feature.

This tag is not used for highway=motorway, because all motorways are dual carriageways. In some regions, highway=trunk are always dual carriageway, but in others this tag is used.

(See instead dual_carriageway=no to tag a highway=trunk which is not a dual carriageway in regions where this would be expected)

Usually dual carriageway highways, where each direction of travel is divided by a physical separation or barrier, are mapped with a separate way for each direction of travel, and the tag oneway=yes is added. Position the nodes in alignment (as shown in the example).

Also consider adding motorroad=* if foot and bicycle access is restricted, or add access=* restrictions specifically.

Rationale

There is no known, reliable and automatic method that would allow distinguishing whether oneway=yes is oneway road or a part of bidirectional roads mapped as two ways. For example there are dual carriageway highway=residential[2].

Practical use includes distinguishing roads where bicycle contraflow is missing from ones where it is not needed[3]. And special rendering for such roads in maps of a high detail[4].

Note that in some regions it can be assumed that all oneway=yes major roads (highway=trunk, highway=primary, highway=secondary, highway=tertiary) are dual carriageways.

See also

  • highway=motorway - a motorway or freeway. While almost all motorways are dual carriageway, divided highways, this tag is not used in that case, since it is implied by the tag highway=motorway.
  • expressway=yes/no - commonly used in the United States to specify whether a dual carriageway "divided highway" has high-speed design features and limited access to adjacent properties or partial grade separation.
  • motorroad=yes/no - specifies whether or not highways have motorway-like access restrictions. Commonly used in parts of Europe and Japan to specify a road designed for motor vehicle use only.

References

  1. Mateusz Konieczny mapping
  2. Retoryka in Kraków, Poland
  3. That is why dual carriageways in Kraków were mapped with this tag by User:Mateusz Konieczny
  4. That is why this tag was used in Seattle