[OSM-talk] zones for motorway/in town/outof town?

[Guenther Meyer]

Am Thursday 21 May 2009 schrieb Lester Caine:
> ALL roads have a defined maximum speed limit ... is this just a matter
> of 'conversion to english'? The fact that a road does not have a
> specific sign is not something that maxspeed is concerned with? At least
> in my reading of the guide lines on maxspeed.
>
right, all roads have a defined limit.
the proposal is:
if there is a sign for a speed limit: use maxspeed = ...
if not: use zone:traffic = ...
  the maxspeed here can be derived from the zone tag.



> > my first suggestion was exactly this: why not use and extend the already
> > existing tags for that, like "maxspeed = DE:in_town".
> > but after some discussion it was clear that such a tag would imply more
> > than just certain speed limits, as I already mentioned. that's why the
> > idea of using a more generic key was coming up.
>
> A key on a road segment is a lot more practical than defining another
> layer of complexity.
I agree with you. I would set those zone tags on the roads, not on a polygon.

> And I can understand that maxspeed=DE:in_town makes a lot of sense since
> a global change to that limit does not require every way to be updated.
> There is a debate on changing the UK 60 limit to 50 which will need a
> lot of changes to these tags, but at present every road I go down seems
> to have had it's default limit lowered to 50 or even 40 anyway. Nearly
> got caught out with a new limit and speed camera last week :(
>

> So the next question has to be - because I'm not SEEING the reason - why
> is 'maxspeed=DE:in_town' a problem? What is it implying other than a
> fact of law?
>
if you are in-town there are the following things implied (I hope I can 
translate them right...):

- maxspeed = 50

- motor vehicles up to 3.5t can freely choose the lane on which they want to 
drive on streets with more tahn one lane for the driving direction. also they 
can drive faster on the right lane as other cars on the left lane.

- parking is allowed up to 5m before a railroad crossing sign (St. Andrew's 
cross?)

- steady parking for trucks with more that 7.5t is not allowed in residential 
and clinic areas

- for parking in the dark parking lights are enough

- if you like to overtake another vehicle you must not signalize this with 
horn or flasher

I know, that not all of these are currently relevant for osm. but if the day 
comes, when such data will be important, it's easier to alter the central 
definiton of "DE:in_town" than to add new tags for that to every single road.


> I would also point out that maxspeed needs a tidy up anyway since it
> does not have any provision for my previous note about VARIABLE speed
> limits. These are being applied more and more to UK motorways to cope
> with the congestion, and are changed based on traffic conditions. Roads
> in residential areas my also have lower limits during school days at
> start end end times.
variable depending only on? or other things?
I have writtena proposal on the german list some time ago to allow the tagging 
of time-dependant resctrictions in an easy way, that would be also machine- 
and human-readable. but I don't know if it is used by someone...




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