[Talk-GB] Visualising speed limits

Colin Smale colin.smale at xs4all.nl
Fri Oct 29 21:52:38 BST 2010

On 29/10/2010 22:22, thomas van der veen wrote:
> Hi,
> I recently started mapping in South Hampshire and enjoying it, great 
> fun. I started adding some maxspeed tags to some roads as sometime the 
> type (primary, secondary, tertiary) doesn't always match the actual 
> speed limit of the road in question I noticed. Or sometime the speed 
> limit changes for certain stretches of road. To make this a bit easier 
> I thought that having a map (no pun intended ;) where I can see based 
> on the colour of the road what speed limit has been set in the 
> database (either implicit or explicit) . That way I can could easily 
> tell where it is incorrect and fix it.
Hi Thomas, welcome to OSM!

You might like to take note that nothing is implicit in OSM. There are 
no "defaults" as renderers or other consumers of the map data are 
unconstrained as to how they handle missing tags. Ideally all roads 
should have maxspeed explicitly tagged, even if it could be implied from 
the road class or other information. The maxspeed map that Lennard 
referred to shows only the explicit maxspeed information; so the roads 
which are missing this information are also immediately obvious.

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