[Tagging] roundtrip

[Paul Allen]

On Fri, May 25, 2018 at 1:51 PM, Peter Elderson <pelderson at gmail.com> wrote:

> Looked it up, of course. Definitions are not that clear-cut. Generally,
> round trip means that you return where you came from, some definitions say
> along the same route, some say mostly along the same route but not
> necessarily. I think the less strict definition covers the usage on osm,
> except for the term "ciircular", best avoid that.
>

I'm not an expert on bus routes.  But I am British, so I can tell you one
Briton's (imperfect) understanding
based on how I've seen these terms used.

A circular route encompasses an area whereas an ordinary route does not.
An ordinary route
may be A->B->C->B->A whereas a circular is A->B->C->D->A, where B and D are
not close to
each other ("close" is vaguely defined).  It's not clear because all buses
in my town are forced,
by the one-way system in the town centre, to loop around the town centre.
Technically all
the routes are circular (because of that one-way system) but I'd regard
only one of them
as such.  The rest are shaped more like ---------------O where the "O" is
the one-way
system.

A round trip has only one terminus (and that may only be a terminus at the
start and
end of the timetable.  A non-roundtrip route is A->B->C [alight] [embark]
A->B->C
whereas a roundtrip would be A->B->C->B->A or, in the case of a circular,
A->B->C->D->A.  In the case of a circular roundtrip you can get on at B and
off
at D even if C is the furthest point from A.  In either case you can get on
at A and get
off at A without having to alight in between.  If you are required to
alight at C
then it is a return journey, not a round trip.

In the case of tour buses or boat tours, there is not only one terminus but
that
terminus may also be the only point at which it is possible to alight or
disembark.
Such routes also tend to be circulars so that you don't see the same
scenery twice.

Whether or not the tags were intended to make those distinctions or
something else
is another matter.  Having tags that don't match common British usage is not
helpful.  OTOH, I'm not sure what mapping benefit there is in tags with
those
meanings.

-- 
Paul
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