|dual_carriageway = yes|
|Specifies that a highway is a dual-carriageway road (divided highway)|
|Used on these elements|
|Status: in use|
|Tools for this tag|
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. A typical dual carriageway is not using this tag.
How to map
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).
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.
- 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.