[Tagging] new role for route relations: reverse

Jo winfixit at gmail.com
Mon May 28 18:44:44 UTC 2018

This is really specific to that particular route relation. So adding note
tags to the underlying way doesn't sound right to me.


2018-05-28 19:28 GMT+02:00 Johnparis <okosm at johnfreed.com>:

> I'm not sure exactly what you're describing or why a new role is needed.
> If the bus traverses the way twice, once in each direction, you simply
> include the way twice. "Magic turntable" is a good description. These are
> fairly common in France, which (not surprisingly) has a lot of cul-de-sacs.
> The bus ordinarily finds a way to turn around so the bus moves toward its
> front, but I'm not sure it makes any difference to anyone what gear the
> driver is using. First gear, second gear, reverse gear -- does it really
> matter?
> I conjured up two images before seeing Paul's "magic turntable" comment.
> The first was a helicopter that winched the bus into the air and turned it
> around. Again, what difference does it make to the mapper or consumer?
> The second was an actual turntable -- the terminus of the San Francisco
> Cable Car at Powell and Market. Nothing magic about it.
> I have no problem with inventing a new tag (or role), but "reverse" sounds
> too much like the deprecated (in PTv2) "backward" to me. Maybe
> "reverse_gear"?
> The best reason I can think of for this is to warn other mappers that
> something oddball is happening here and so please don't assume that just
> because there's no room for the bus to turn around, there's no need to
> remove this way from the route. But that can be solved with a simple note=*
> tag on the way.
> John
> On Mon, May 28, 2018 at 6:09 PM, Paul Allen <pla16021 at gmail.com> wrote:
>> On Mon, May 28, 2018 at 3:40 PM, Erkin Alp G├╝ney <erkinalp9035 at gmail.com>
>> wrote:
>>> Does it have any stops in the street it reverses into?
>> Not that I've seen.  But if somebody asked to get off there I'm fairly
>> sure that most of the
>> drivers would permit it.  And since it backs as far as a bench, I'm also
>> fairly sure most
>> drivers would let somebody sat on the bench waiting for the bus to board
>> there.
>>> If not, it is not formally a part of the route and just a convention.
>> Yes, but without it the route involves a role called "magic_turntable."
>> If this were an end of route turnaround at a terminus then it's not
>> mappable.  What
>> happens when passengers are not on board and the bus is technically out
>> of service
>> are not part of the route.  But this is done with passengers on board in
>> the middle of
>> the route.
>> Sure, renderers and routers might cope with the bus going to point X and
>> magically
>> switching its direction of travel by 180 degrees but it's a bit puzzling
>> for data
>> consumers.  Does the bus go out of service there?  Is it a terminus?  Has
>> the mapper
>> made a big mistake in the route?  Did some other mapper come along and
>> accidentally delete part of the route?  Etc.
>> Unless having role=reverse is going to cause big problems for renderers or
>> routers I don't see any problem with having it.  I doubt it's going to
>> get used
>> often, so it's not a problem regarding data storage.  But I could be
>> wrong.
>> --
>> Paul
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