[OSM-newbies] Small streams under minor tarmac roads

[Andy Robinson (blackadder-lists)]

exnpo-openstreetmap at yahoo.co.uk wrote:
>Sent: 11 November 2009 12:49 PM
>To: newbies at openstreetmap.org
>Subject: [OSM-newbies] Small streams under minor tarmac roads
>
>Greetings,
>
>What is the standard way of mapping small streams under rural minor
>unclassified roads?
>
>If I'm standing on a bridge, however tiny, it's a bridge!
>
>However, in my area there's loads of streams criss-crossing the countryside
>and I'm not at all sure how to map a stream, which often dries up in
>midsummer, which goes into a smallish diameter - 600mm - concrete pipe
>which then passes under a tarmac road, about 3 metres in width, and
>reappears the other side where the stream continues it's way on the
>surface?
>
>I've considered pipeline and tunnel but don't think their use applies here?
>
>Any advice please?
>

There is usually an easy way to tell what the structure is. If you look at
where the water disappears and re-emerges you should see one of the
following:

1. A circular pipe, often of concrete but perhaps also of
corrugated/galvanised steel.
2. A rectangular concrete culvert, basically a pipe but a regular
rectangular shape.
3. No clear structures but perhaps bricks at each side and possibly no
bottom.

Cases 1 and 2 I would tag as a "culvert" because that's the technical
engineering term for them. So culvert=yes and level=-1 perhaps. This is
unlikely to render currently but only needs good support of tagging to see
that change.

Case 3 will normally be a bridge and often bridges will also have a
guardrail/parapet on each side of the road where the bridge crosses the
stream or drain. Watch out though because some form of barrier may also be
present above a culvert to protect folks and vehicles ending up in the
ditch.

Hope this helps

Cheers

Andy