[Tagging] pipeline flow direction; was: Feature Proposal - RFC - Pipeline Extensions

Rainer F├╝genstein rfu at oudeis.org
Sat Nov 15 21:38:53 UTC 2014



f> Found one more, loop=*
f> Some month ago we were talking on this list about flow of waterways and
f> pipelines.

f> The far I remember flow_direction=forward/backward/both was mentioned to
f> tag the direction a pipeline or canal is used.

agreed; it is better to define a tag that can also be used in other

I glimpsed over the pipermail web pages - can't reply directly,
therefore a summary:

* there are pipelines which can reverse the flow and others which
can't. therefore it is not wise to assume "oneyway=yes" (or similar)
by default.

* presumably, the post by Bryan Housel ("So my reading of that was
that pipelines imply oneway=yes") was made before the "loop" tag was
added to the PipelineExtension proposal.

* pipelines are usually built to transport the substance only in one
direction. for such pipelines, it is not possible to reverse the flow
by just pressing a button. they have to be constructed to do so, which
some/most newer pipelines are.

* I don't see the point of flow_direction=backward/forward on a
pipeline. it doesn't make sense to draw the way in one direction and
specify flow_direction=backward.

since it (will be) a generic tag, forward/backward may make sense
in other cases. for pipelines, I propose flow_direction=both and
flow_direction=oneway. if the latter is disputed, using just
flow_direction=forward (and never =backward) is a good alternative.

* if the flow direction is unknown, just don't add the flow_direction


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