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Public-images-osm logo.svg tunnel = flooded
Waterway free flow tunnel.png
A long (over 100 meters) tunnel where flowing water or other fluid prevent humans from safely walking inside. Show/edit corresponding data item.
Group: placement
Used on these elements
should not be used on nodesmay be used on waysshould not be used on areasshould not be used on relations (except multipolygon relations)
Useful combination
Status: approvedPage for proposal

A flooded tunnel is an artificial structure intended to channel water on a significant distance. Its dimensions and length can allow human to fit inside but safe walking is impossible due to high amount of water or other fluid expected in operation. Water may be punctually absent for maintenance purpose or dry weather but this doesn't make the tunnel safe and you may expose yourself to drowning hazard at any time when walking inside.

Such tunnels are different from tunnel=culvert for which dimensions are restricted to building or way it is supposed to go underpass. They are also different from tunnel=yes where a tow-path can usually exist for human to safely pass and where water level is usually controlled for safety reasons, like Canal Saint-Martin in Paris.

man_made=pipeline is actually different from tunnels since a pipeline is built from tubes assemblies.

tunnel=* only represent a man made infrastructure and doesn't presume of the flowing regime. You should use waterway=canal, waterway=drain, or waterway=pressurised to give such details.

How to map

On the path of the tunnel, draw a line and put tunnel=flooded on it. You can add location=underground and a negative layer=* value

See tunnel=* and waterway=* for a description of the preferred way of connecting channelised waterways to adjoining waterway sections.


Photo Tagging Note
Headrace tunnels map


Horizontal tunnels carrying water from intakes to penstocks. Such ways have a pipe flow regime, their inlet are always below the water level and no air can get inside.
Underground water tunnel outlet


A headrace tunnel works at atmospheric pressure and water have a free surface while flowing inside. Its inlet is designed to be always above water level and air can get inside too.