Key:tunnel
+/- tunnel
A tunnel is an underground passage for a road or similar.
Properties
Tools for this tag
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tunnel=* is used for roads, railway line, canals etc that run underground (in tunnel).
For some grade separated crossings it may however be debatable if the lower way is in the tunnel or if the upper way is on a bridge=*. In general, if the lower way is long and surround by earth it is almost certainly a tunnel; and if the lower way is short and the upper way is supported on concrete, brick on metal pillars / beams then that is almost certainly a bridge. There are however situations where it is a matter of personal judgement, but it is preferred to either tag the lower way as tunnel or the upper way as a bridge but not both.
Where the water from a smaller stream, drain or even cattle crossing passes under under a structure or building consider using tunnel=culvert in place of the tunnel=yes used for larger tunnels for roads or railways or canals.
For tunnels which are open on one side, often found on mountain roads or ways underneath a building, use covered=yes in place of the tunnel.
For a structure that carries water or another liquid some considerable distance then it may be more appropriate to tag it as a pipeline using man_made=pipeline.
How to map
Split the way in question at the points were the tunnel starts and ends and add the tunnel tag. It is best to avoid having a tunnel continue to a junction that is not in a tunnel by splitting the way prior to the junction. It is also good practice to add a layer=-1 tag in most situations to indicate that it runs below features with a layer tag. Some people consider this to be unnecessary however. For metros/subways it is often convenient to use layer=-2 to accommodate underground passages for pedestrians between the tunnel and the surface.
Where the approach to the tunnel is in a cutting this can be identified with cutting=yes. Note that a layer=-1 tag is not required on a cutting or embankment given that the way is on 'modified ground level'.
It may also be useful to add maxheight=* and maxwidth=* if there are publicised restrictions and use access=* if there restrictions on use by certain classes of vehicle or user.
If the tunnel has a name this can be specified using tunnel:name=* although there is still some debate on the best method to include a name of the tunnel as discinct from the road/railway etc that goes through it. lit=* can be included to provide information about any lighting in the tunnel (or not).
Tagging
tunnel=building_passage
Ways that go through a building and have walls to all sides should be tagged with tunnel=building_passage. The building and the way share the same node at the entry and exit points of the building. The way is split at the entry and exit nodes and only the part covered by the building is tagged with tunnel=building_passage. The layer has to be the same as the building. So if the building doesn't have a layer tag, the way doesn't need one either.
When building_passage should not be used: It is not meant to be used for indoor mapping. The walls at both sides (and the top) of the tunnel are considered outer walls of the building, which can have entrances that lead into it (This proposal doesn't cover entrances inside building passages). For indoor mapping indoor=yes can be used. It is also not meant for ways that go through something else than a building.
Wullersdorf Pfarrhof Durchfahrt
Richard-Matthäi-Haus (Hamburg)
covered=arcade
An arcade is a succession of arches, each counterthrusting the next, supported by columns or piers or a covered walk enclosed by a line of such arches on one or both sides.[1] Such ways should be tagged with covered=arcade. If the arcade is part of a building, the building and the way share the same node at the entry and exit points. The way is split at the entry and exit nodes and only the part covered by the building is tagged with covered=building_arcade The layer has to be the same as the building. So if the building doesn't have a layer tag, the way doesn't need one either. Use arcade:left=open or arcade:right=open to define which side of the way is open.
When arcade should not be used: It is not meant to be used for indoor mapping. The wall on one side is considered as an outer wall which can have entrances that lead into the building. For indoor mapping indoor=yes can be used. Also it is not meant to be used for simple roof overhangs or blind arcades.
a typical arcade in South Tyrol
covered=colonnade
Similar to arcades, but differ architecturally, a colonnade denotes a long sequence of columns joined by their entablature, often free-standing, or part of a building.[2] Such ways should be tagged with covered=colonnade. If part of a building, the building and the way share the same node at the entry and exit points. The way is split at the entry and exit nodes and only the part covered by the building is tagged with covered=colonnade The layer has to be the same as the building. So if the building doesn't have a layer tag, the way doesn't need one either. Use colonnade:left=open or colonnade:right=open to define which side of the way is open.
When colonnade should not be used: It is not meant to be used for indoor mapping. The wall on one side is considered as an outer wall which can have entrances that lead into the building. For indoor mapping indoor=yes can be used. Also it is not meant to be used for simple roof overhangs.
Kanslihusets arkad (missleading name, it's a colonnade, not an arcade)
the colonnade of famous Baroque architect Gian Lorenzo Bernini in front of St. Peter's in Rome
tunnel=avalanche_protector
A variant of "arcade" is tunnel=avalanche_protector and should be used is in case of tunnels alongside mountains. These constructions stand for themself and are not attached to a building. Their purpose is to protect the highway or railway from avalanches and landslides. Use avalanche_protector:left=open or avalanche_protector:right=open to define which side of the way is open ("open" in case of avalanche protectors means, that light and air can enter on that side).
Damüls, Faschina Hahnenköpfle-Galerie
Rendering
Osmarender (version 4) renders tunnels as dotted outlines with lines for the abutting face.
Mapnik draws tunnels on highways with dotted outlines and a lighter fill color for the road and with curved color transitions on tunnel entrances.
Proposals
- Relations/Proposed/Bridges_and_Tunnels - group multiple tunnel elements with a relation
- Proposed_features/building_passage
