[Openstreetmap] Site Update

[Simon Hewison]

I've noticed that sometimes the WMS server that the tiles are pulled
from doesn't render anything other than landsat for some tiles.

Would it be possible for the WMS server to realise that there's some
sort of error in fetching/rendering the roads, and at least set the HTTP
Expiry time to an shorter period of time if it can not render all
requested layers?

(example: Look for Barnet, United Kingdom)

-- 
Simon Hewison