[mkgmap-dev] road_speed inside cities

Wed Apr 29 09:29:31 BST 2009

Carlos Dávila wrote:
> Torsten Leistikow escribió:
>   
>> Carlos Dávila schrieb:
>>   
>>     
>>> Would it be possible to
>>> tell mkgmap that highways other than residential but inside a place
>>> polygon should have a lower road_speed?
>>>     
>>>       
> [...] there is a lot of ways
> without maxspeed tag (at least in Spain). That's why I thought parsing
> ways inside city polygons could be a good approach.
> Regards
> Carlos
> _______________________________________________
>   

I'd like to say that I agree with Carlos here - this has been the
subject of a friendly argument between me and another OSMer whom I know
personally.

I argued that it would be very nice to allow the "place=xxx" polygon to
carry a maxspeed tag [or maybe a "maxspeed:primary",
"maxspeed:secondary" (etc) set of tags]. I mapped a village at
http://www.openstreetmap.org/?lat=51.5467&lon=-3.69937&zoom=16&layers=0B00FTF
where the entire place is under a 20mph/32kph limit. Now it just so
happens that I've not yet drawn a "place" polygon for that village(!)
but I normally do. And it would have been much better to be able to set
"maxspeed=32" on the *polygon* rather than having to tag every little
road in the entire village.

You could expect tagged polygons to cascade: each polygon 'inherits' the
"maxspeed:whatever=" attributes from the polygon outside it. This then
means that mkgmap need not have built-in knowledge of each country's
national speed-limit rules: you just expect the "country" polygon to
specify it.

I suppose this sort of thing would need a bit of discussion on the OSM
tagging proposals forum.... not just here.

I've seen a few cases near my home (Swansea, South Wales) exactly as
Carlos reported: my Garmin favouring a "B" road through the town because
it didn't have a specific "maxspeed" tag, whereas the main road did.

Steve

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