[Tagging] roundtrip

Peter Elderson pelderson at gmail.com
Fri May 25 20:03:28 UTC 2018

As to the term roundtrip, I have inderstood this completely wrong, probably
because the Dutch term Rondwandeling literally translates as roundtrip. Now
that I've been set straight, I think the correct meaning should be
documented on the wiki page. The bracketed "explanation" (circular route)
should be removed.
The correct meaning is something like:
roundtrip=yes means you can return to the starting point by (almost) the
same route and transport method.

Personally I would stay away from payment, embarking/boarding, ticket types
etcetera. If I can cross the road, get another ticket and return tot the
starting point in another bus, I would still consider it roundtrip=yes.

Which in PT would be the default, I think.. So you would only tag
roundtrip=no if you can't return the same way.
I don't know enough about PT tagging to know if that's useful in that
context. If so, a use case would be nice on the wiki page.

With hiking routes, this meaning of the tag is not useful, I would say.
Current use is, sadly, opposite the actual meaning.

>From the Dutch forum I get that they think it's important to tag circular
routes as such, even when they are geographically not circular routes
(circular in the sense that you just keep following the markings and then
you end up in the same place you started.) Tagging geographically circular
hiking roads as non-circular, I can't think of a use case, but that's fine.

I agree that circular=yes|no is confusing, because a special meaning of
circular in the context of a route is meant, not literally circular in
shape. Route:circular=yes is cool with me.

The other important attribute for the Dutch is oneway or not, for hiking
and biking that means that the waymarks are onesided. That happens more
than you would think! oneway=yes in combination with the correct sorting
direction should be enough I think?

In sum, just one additional key needed, and of course correction tagging of
roundtrip=yes to route:circular=yes.

Probably have to adapt some validation and detection tools, too.

2018-05-25 15:53 GMT+02:00 Johnparis <okosm at johnfreed.com>:

> I would generally agree with all your points.
> A slightly more formal definition (though not fully rigorous) for me would
> be: a circular route is one in which, from any boarding area, you can
> return to the same boarding area without being forced to disembark.
> I say boarding area rather than point because of the fairly frequent case
> where the dropoff and pickup points serve the same area (such as a train
> station) but are not necessarily identical.
> The example I gave in the other thread, I believe, is marketed that way
> because people are indeed supposed to leave the bus, though I would imagine
> that since most people use weekly or monthly passes, most drivers would
> probably look the other way.
> https://www.openstreetmap.org/relation/8140184
> Thorsten's description is good, but technically pretty much any bus route
> is a roundtrip (circular) topologically. A typical route is:
> A -> B -> C -> (forced disembark) -> C' -> B' -> A' -> (forced disembark)
> -> A ...
> Typically B and B' are on opposite sides of a two-way street. That's the
> simplest example. Topologically it's the same as a circular route, because
> the bus makes a U turn at each end and continues. So it's a question of
> marketing and general public understanding, more than mathematical rigor.
> But the variations are bewildering.
> Personally, I track circular routes for validation purposes. As I
> understand Public Transport version 2, every route variant requires a route
> master, even if the master has only one variant. So masters with one
> variant are oddballs; most routes have at least two. A master with only one
> variant is typically either (a) a circular route (so I mark them in my
> private database), (b) a PTv1 route (thus needing an upgrade), or (c) an
> error (thus needing further investigation).
> I would mark the OSM example above in my data as a circular route, so I
> won't flag it as needing further work, but it would not meet my more formal
> definition of a circular route, because of the forced disembark, so I would
> not consider it as qualifying for a "roundtrip=yes" tag.
> If there is sentiment to change the name of the tag, I would suggest
> "route:circular=yes". (There are "only" 25000 in the OSM data, so it might
> be manageable.) I don't like "circular=yes" because it's so vague.
> (example: building=silo circular=yes ?)
> On Fri, May 25, 2018 at 1:23 PM, Peter Elderson <pelderson at gmail.com>
> wrote:
>> Oops, I didn't think this topic would generate so much response, even
>> though I charged a bit in the first mail.
>> Let me try to make some sense of it. I have seen enough use cases, I
>> think.
>> a. There are two use cases which use the actual definition on the wiki: a
>> geagraphically closed route, start-point=end-point. One is about marking
>> routes as roundtrips based on JOSM validation, then monitoring if the chain
>> had broken so you can fix it. The other is marking an unfinished  route as
>> roundtrip in order to detect it for completion. To me, this is almost the
>> same use case.
>> b. A range of use cases are opposite: a geographical roundtrip has to be
>> regarded as non-roundtrip, or a geographical non-roundtrip has to be
>> regarded as a roundtrip anyway.
>> Could we agree that the wiki should cover b.?
>> I think this does not exclude a.
>> If anyone judges that a geographical roundtrip should explicitly be
>> tagged as roundtrip=yes, ok.
>>  do think that when one of the use cases under b. applies, then you have
>> an exception to what the map says, with a reason. Then this takes
>> precedence over the geographical default.
>> This could be a geographical roundtrip tagged as roundtrip=no for
>> whatever reason, or a geographical non-roundtrip tagged as roundtrip=yes,
>> for whatever reason. It would be nice to know the reason, of course. For my
>> part, "everybody/nobody here calls this a circular line" is reason enough.
>> Could we agree on that too?
>> If so, all that remains is add this to the wiki.
>> --
>> Vr gr Peter Elderson
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Vr gr Peter Elderson
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