[OSM-talk] waterway - "routable network" and reservoirs/lakes

Maarten Deen mdeen at xs4all.nl
Tue Jul 28 06:01:51 UTC 2015

On 2015-07-27 23:39, Lester Caine wrote:
> On 27/07/15 20:55, Mike Thompson wrote:
>> I assumed that when the wiki spoke about "routable" it was referring 
>> to
>> the water flow rather than boat/ship/barge traffic.   In any event, a
>> routing engine for boats could use the presence of a dam or weir
>> (combined with the absence of a lock) to deduce that ship navigation 
>> was
>> not possible.
> 'This way used should point in the direction of water flow' is only
> applicable to non-tidal flows, and reservoirs may well control water
> flow in a way that makes a 'water flow map' somewhat difficult to 
> deduce.

Only if they are entirely artificial. A dam in a river or stream makes 
the direction of water very clear: high to low. Only when there is an 
artificial reservoir with no natural tributary it is not clear.

> The use of 'routable network' is rather ambiguous, but this is little
> different to the problem of routing through other land based open areas
> where several waterway features link into an area of open water. The
> jury is still out on putting in all the paths through the area, but if
> there is a navigable route designated through a water body it should be
> drawn, but an imaginary link just showing water flow should not be
> necessary? Any routing process should be able to deduce the relation,
> there is no need to draw it.

Causality. Does a water area need a way indicating the direction of 
water? Of is it that when you draw a way through the water area it 
should point in the direction of the water flow.


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