Key:tunnel

tunnel=* is used for roads, railway line, canals, etc. that run in a 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 surrounded 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 and 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.

For covered passages which are open on one side along the way, use covered=* in place of tunnel=* (e.g. covered=arcade or covered=colonnade). One exception are landslide/avalanche protectors on mountain roads, which are tagged as tunnel=avalanche_protector.

Where the water from a smaller stream, drain, or even cattle crossing, passes under a way structure or a building, consider using tunnel=culvert in place of the tunnel=yes used for accessible and larger tunnels for roads, railways, etc.

When the waterway=* runs underground for a considerable distance, you can use tunnel=flooded especially when the duct isn't designed to be safely accessible in operation or man_made=pipeline for sections built with tube assemblies.

Power cables (power=cable) or pipelines (man_made=pipeline) buried underground should not be tagged as tunnels. The location of a buried cable may optionally be tagged as location=underground or location=underwater. However, if the cable or pipeline is located inside a self-supporting tunnel, it may be tagged as tunnel=yes. Such dedicated utilities tunnels are sometimes found in large cities.

How to map

Showing a tunnel that continues to the junction on the left (wrong) and that is terminated before the junction on the right (correct).

• 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.
• Most tunnels should be tagged with layer=-1 or another suitable negative value (exception: tunnel=building_passage). For metros/subways or other very long ways, 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=* tag is not desired on a cutting or embankment unless there are several layers of objects that need to be differentiated.

tunnel=building_passage should normally not have a layer assigned as there is no clear above/below relation to the building, but a layer may be required when there are several layers of building passages.

It may also be useful to add maxheight=* and maxwidth=*, if there are publicised restrictions and use access=*, if there are restrictions on use by certain classes of vehicle or user.

If the tunnel has a name this can be specified using tunnel:name=* (24,911 uses by 1815 editors as of 2024-05-16) although it should be clear that this is still an indirect way of mapping "a tunnel" (it is a property of the feature which is in the tunnel and refers to a tunnel which may be mapped as a distinct object as well). There is still some debate on the best method to map the name of tunnels and how to represent the tunnel as its own object.

lit=* can be included to provide information about any lighting in the tunnel (or not).

Values

The following values are now considered in OpenStreetMap according to classification upside:

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Additionally, the following values are in use with waterways:

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Rendering

tunnel=yes, tunnel=building_passage, and covered=yes are rendered by the default OpenStreetMap styling.

• 
  OSM Carto draws tunnels on highways with dotted outlines and a lighter fill colour for the road and with curved colour transitions on tunnel entrances.
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Possible tagging mistakes

tunnel=covered

		$1%
		$1%
		$1%
		$1%

More details at taginfo

• tunnel=covered

If you know places with this tag, verify if it could be tagged with another tag.
Automated edits are strongly discouraged unless you really know what you are doing!

See also

• covered=*
• highway=corridor
• Proposed features/building passage – accepted proposal
• man made=tunnel – simple way of indicating the outline of a tunnel and grouping together all features for that tunnel
• Relations/Proposed/Bridges and Tunnels – group multiple tunnel elements with a relation