[OSM-talk] [RFC] Deprecating the use of Tag:highway=stop in favour of Key:stop

[Roy Wallace]

On Mon, Aug 24, 2009 at 3:39 PM, David Paleino<d.paleino at gmail.com> wrote:
> On Mon, 24 Aug 2009 08:53:53 +1000, Roy Wallace wrote:
>
>> On Sun, Aug 23, 2009 at 8:48 PM, David Paleino<d.paleino at gmail.com> wrote:
>> > Hello,
>> > I'd like to start discussion on the deprecation of the Tag:highway=stop in
>> > favour of using stop=yes/both/-1.
>>
>> First impression: the value of the tag is extremely ambiguous, and in
>> no way self-explanatory. I don't like it at all.
>
> It has the same values as oneway=*. If you use Key:oneway, you know how to use
> Key:stop.

1) no, it doesn't (yes/both/-1 vs yes/no/-1)
2) the meaning of "yes" and "-1" is different for oneway! ("yes" means
"forward" as opposed to "on the last node"; "-1" means "in the reverse
direction" as opposed to "on the first node")

Seriously, stop=-1 is not self-explanatory! Even if the values of
oneway matched up (which they don't), it still wouldn't make stop=-1
self-explanatory.

> Aren't we tagging what we see in the real world? I'm of the opposite opinion,
> we tag stop *signs* (horizontal or vertical signs), and we're trying to relate
> those signs to the junction they have effect on.

If you want to put a stop *sign* on the map, use a separate node with
traffic_sign=*.

If you want to describe an attribute of the intersection of ways, it's
quite alright to assign this attribute to the way/intersection itself,
because it is indeed an attribute of the way/intersection.

>> How about stop=at_last_node, stop=at_first_node and
>> stop=at_first_and_last_node? More verbose, but a lot clearer than
>> yes/-1/both.
>
> That can be done too. More concise:
>
>  stop=first (-1)
>  stop=last  (yes)
>  stop=both  (both)

Hrmm that is more concise, but I think less self-explanatory (remember
that not everyone reads the wiki before editing). E.g. stop=both could
be misunderstood to mean "both directions", or "both intersecting
ways", etc.

Also, need to clarify something...:

Let's say way A is drawn from West to East, then at some point becomes
(intersects with) way B, which continues to the East.
And let's say East-bound travelers have to *stop* at the junction (for
some reason), but West-bound travelers don't.

This would be tagged as A being stop=at_last_node. Right?

For West-bound travelers, at the instant they cross from B to A, this
would imply that they should stop, because they're at the last_node of
A. Which is not the case. In other words, it would seem to me that the
proposal needs clarification in the form of something like:

"The stop=* tag is applied to a way to specify the node at which the
stop sign applies. However, the stop sign only applies when the node
is approached from the way that is tagged."