[OSM-newbies] Highway Types and Speed Limits

[Morten Kjeldgaard]

On 14/10/2009, at 10.06, Trevor Hook wrote:

> When I'm tagging say, a residential street, should I also be tagging  
> the 30mph speed limit that the residential street implies (at least  
> in the UK) or should I only tag if the street has a non-standard  
> speed limit such as 20 or 40mph?

Is it really a good idea to tag the speed limit with a value? Say the  
government decides to decrease the speed limits of all rural roads  
with 5mph (e.g. to reduce CO2 emission), then you have to correct the  
tagging on all roads. And it can't be done using a script, since some  
roads with the same speed limit value maybe shouldn't be changed.

I think it would be better to use a road classification scheme for  
speed limits; then the mph value only needs to be changed one place,  
namely the database entry that ties a certain classification to a  
speed limit.

Cheers,
Morten