[Tagging] waterway=penstock to complete pipeline tagging

[Christoph Hormann]

On Monday 05 October 2015, Martin Koppenhoefer wrote:
> >
> > probably not very practical to
> > differentiate between 'pipelines with a pipe' and pipelines without
> > a pipe' underground.
>
> can you give an example for a pipeline without a pipe?

Apart from the pressure tubes of hydropower plants the most common case 
is probably sewer pipes.  For general transport pipelines cutting them 
into rock is rare due to the high costs.  Hydropower penstocks are an 
exception mostly due to the high volume high pressure combination and 
sewage due to the space constraints in urban environments.

-- 
Christoph Hormann
http://www.imagico.de/