|Group features of a tunnel|
|Proposal status:||Draft (under way)|
|Definition:||Indicate the outline of a tunnel and group together all features for that tunnel|
The tag man_made=tunnel should be used to indicate the outline of a tunnel and group together all features for that tunnel.
Currently there exists the key tunnel=* to indicate that a certain OSM way runs through a tunnel. Furthermore the proposed relation tunnel can be used to group together all features of a tunnel. The proposed tag man_made=tunnel is a step in between: it allows to group together all features of a tunnel without the need of a relation.
A similar proposal has already been accepted for bridges, see man_made=bridge.
The tag is already in use more than 70 times, see taginfo. (Note: Several cases, especially those where only a single node has been tagged, do not follow this proposal and are not suitable as examples.)
A very simple example where the outline of a tunnel with two ways has been tagged exists at the "Cinco Señores" junction in Oaxaca, Mexico:
- Newspaper article with pictures of the tunnel: http://www.semanarioevidencias.com/?p=75802
- Link to OSM object: https://www.openstreetmap.org/way/297683049
Another fine example is the "Guldborgsundtunnelen" in Denmark:
- Wikipedia: https://da.wikipedia.org/wiki/da:Guldborgsundtunnelen
- Page of Danish road administration with pictures: http://www.vejdirektoratet.dk/DA/viden_og_data/statens-veje/broer/Sider/Guldborgsundtunnelen.aspx
- Link to OSM object: https://www.openstreetmap.org/way/415149230
Draw the outline of the tunnel as a closed way and apply man_made=tunnel to it. Connect all OSM ways running through the tunnel to the outline. The OSM ways are tagged with tunnel=yes and layer=*, as usual. On the outline add the same layer=* as on the OSM ways running through the tunnel. Ways that do not run through the tunnel but rather over or under it should not be connected to the outline of the tunnel.
Attributes of the tunnel itself should now be added to the outline. An example would be the key name=*: add the name of the tunnel to the outline. The name of the roads that run through the tunnel should only be tagged on the OSM ways and not on the outline.
Some useful combinations are:
- name=*, name of the tunnel, e.g. name=Nordkapptunnelen. Sometimes the name can be copied from a sign near the tunnel entrance.
- ref=*, reference number or code of the tunnel itself. Sometimes this number or code can be copied from a sign near the tunnel entrance. Do not use the number of the road that runs through the tunnel.
- layer=*, same as the layer of the roads running through the tunnel.
- tunnel=building_passage/avalanche_protector, if the tagged object is a building passage or an avalanche protector. Please don't tag the outline with tunnel=yes.
- length=*, length of the tunnel in metres, e.g. length=6870. Sometimes the value can be copied from a sign near the tunnel entrance.
- width=*, width of the tunnel in metres. Note that the maximum allowed width of vehicles should instead be tagged on the OSM ways that run through the tunnel, using maxwidth=*.
- height=*, height of the tunnel in metres. Note that the maximum allowed height of vehicles should instead be tagged on the OSM ways that run through the tunnel, using maxheight=*.
- ele=*, lowest elevation of the tunnel in metres, e.g. ele=-212. Note that a negative value applies to tunnels that run under the sea level. Sometimes an elevation value is indicated by an official sign near the tunnel entrance. In this case is frequently given using the national reference system of the respective country, while ele=* should formally provide the WGS84/EGM96 elevation. The difference is typically very small (less than one metre) and can be neglected. For more detailed mapping ele=* may also be specified on both ends of the tunnel and even at arbitrary points inside the tunnel similar to the scheme suggested for Bridge3D.
- wikipedia=*, if a Wikipedia article about the tunnel exists
Other info like toll fees or access restrictions should rather be added to the OSM ways that lead through the tunnel.
- Tunnels with more than one level
- Tunnels with more than one level can be tagged in a similar manner as described for multi-level bridges in man_made=bridge, with the main difference that the key layer=* of the outline of the tunnel should contain the highest layer number of all the features in the tunnel.
- Long or complex tunnel structures
- Such tunnels can be tagged with a multipolygon relation and this multipolygon relation can then receive the man_made=tunnel tag and other tags as described above.
- Two-dimensional highways in tunnels
- man_made=tunnel can be used to group highways that have been tagged according to Proposed features/area:highway. Don't forget to provide ways that are connected to the tunnel entrances at the outline of the tunnel. These ways need to be tagged with tunnel=yes and layer=*.
- Objects inside the tunnel
- Such objects can be tagged in a similar manner as described in Proposed features/Simplify man made=bridge mapping with the main difference that the value tunnel is used instead of bridge.
Cases that should be tagged differently
- Single way through tunnel
- If there is only one road going through the tunnel, an outline is typically not needed. Specific tunnel information can be tagged on the OSM way using the prefix <tunnel:>, e.g. tunnel:name=*.
- Single node
- Typically it does not make sense to tag a single node with man_made=tunnel. Maybe the node is just a tunnel entrance and the (currently undocumented) tag man_made=tunnel_entrance could be used?
- Underground pedestrian area
- If you intend to map a single underground pedestrian area, then it's typically better to tag it as follows: highway=pedestrian, area=yes, tunnel=yes. Of course, if you want to group several of these areas, then see the section "Two-dimensional highways in tunnels" above.
- Multiple tunnel tubes
- Multiple tunnel tubes should be mapped separately and may be grouped together using a tunnel relation. However rooms or ways inside a larger tunnel tube which are separated by a man made wall could be still mapped with man_made=tunnel.
This tag should only be used on an area that indicates the outline of the tunnel.
The area that has been tagged with man_made=tunnel is could be shown brighter than the background and its outline could be drawn with a dark dashed line. The name of the tunnel could be shown in the center of this area.
- Relations/Proposed/Bridges and Tunnels
- Proposed features/Simplify man made=bridge mapping could also be applied to tunnels
Please comment on the discussion page.