|tunnel = flooded
|A long (over 100 meters) tunnel where flowing water or other fluid prevent humans from safely walking inside.
|Used on these elements
|Tools for this tag
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.
How to 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.
|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.