[Tagging] Clarificarions for highway=speed_camera

[Marc Gemis]

As I see it

* highway=speed_camera is only the "device", the camera, not the sensors
* the direction is mapped via the enforcement-relation {1], the from
and to nodes here could be the sensors


[1] https://wiki.openstreetmap.org/wiki/Relation:enforcement


regards

m.

On Mon, Apr 2, 2018 at 3:18 AM, Nelson A. de Oliveira <naoliv at gmail.com> wrote:
> Sometimes some doubts about highway=speed_camera arise here in Brazil.
>
> The most recent discussion is about:
>
> 1) In iD "speed camera" was translated as "speed sensor" in Portuguese
> and some people are mapping where the ground sensor (which detects the
> vehicle) is located at the road, instead understading and mapping it
> as the camera device itself.
>
> For me it's just necessary to fix the translation, but to solve this
> doubt, "speed camera" means *only* the camera device?
> ie, this device at the right side
> https://wiki.openstreetmap.org/w/images/7/7c/Speed_camera.jpg
>
> People usually understand it as an object that summarizes a group of
> ground sensors + radar + camera.
>
> 2) For simplicity¹ people are mapping speed cameras as a node at the
> highway. I won't discuss this here, but a related problem with this
> is: they are starting to use the "direction" key to specify which side
> the speed camera applies to, when used in a two-way street.
> ie, direction=forward if the enforcement applies only to the same
> direction as the highway way, direction=backward if it applies to the
> opposite direction and direction=both, if the enforcement applies to
> vehicles in both directions.
>
> ¹ simplicity = not knowing/wanting to use an enforcement relation
>
> Their arguments in favor of using direction like this:
> - it's simple to map (since people will not have to use an enforcement relation)
> - it should work exactly like highway=stop's direction (where it
> represents the way direction that the stop applies to)
>
> But what I see:
> - it is ambiguous: it means where the camera is pointing to or it
> means the direction that it applies too?
> - it changes the semantics of "direction"; ie, if we map a speed
> camera with direction=forward meaning "the enforcement applies only to
> the same direction of the way", then how we are going to represent the
> direction the camera is pointing?
> - we already have enforcement relations to represent the direction
> that the enforcement applies (the direction key will then duplicate
> the same kind of information from the relation).
>
>
> On Jan 31 we had the number of highway=speed_camera +
> direction=forward|backward|both as:
>
> Global: 85
> Brazil: 28 (32.94% of total)
>
> On Mar 29 we had:
>
> Global: 103
> Brasil: 41 (39.8% of total)
>
> And today (April 1):
>
> Global:
> highway=speed_camera + direction=forward|backward|both: 116
> highway=speed_camera + other value for direction: 635
> highway=speed_camera without direction: 31196
>
> Brazil:
> highway=speed_camera + direction=forward|backward|both: 55 (47.41% of total)
> highway=speed_camera + other value for direction: 261 (41.10%)
> highway=speed_camera without direction: 2998 (9.61%)
>
>
> So it seems that this kind of "direction" usage is quickly growing here.
>
>
> I have also included some common doubts at
> https://wiki.openstreetmap.org/wiki/Talk:Tag:highway%3Dspeed_camera#Clarifications_about_common_doubts_and_how_people_view_speed_camera
>
>
> Comments, please?
>
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