[OSM-talk] Culvert and average contributor

[SomeoneElse]

  On 26/08/2010 19:29, John F. Eldredge wrote:
> The term "culvert" is also standard usage in American English.  "Tunnel" is generally used to mean an underground passageway large enough for a person to walk through, if not larger.

As has already been said, it's also widespread in British English too - 
although (at least in some places) it doesn't always imply "covered".  
For example, someone might say "this stream has been culverted" to refer 
to a stream that has been forced to run through an artificial concrete 
canyon with no roof on it

There's an example here:
http://www.sepa.org.uk/planning/idoc.ashx?docid=77d6eb29-bede-474f-9258-1fdc14e977f5&version=-1
(sorry for the PDF)

that talks specifically about "enclosed culverting".  I've tended to use 
"tunnel=yes" for a piped waterway or one in a boxed culvert, but would 
be the first to admit that that's stretching "tunnel" way beyond its 
former use.