[Talk-GB] Advice needed for maxweight turning restriction

[ael]

On Sat, Oct 12, 2013 at 08:11:41PM +0100, Ed Loach wrote:
> ael wrote:
> 
> > I have a road with a maxweight (7.5t) sign at one end but none at
> the
> > other end. So I take it that this means that vehicles over this
> weight
> > may not enter from that end.
> > 
> > I have used a relation tagged with
> > type=restriction:maxweight
> > maxweight = 7.5
> > restriction = no_entry
> > 
> > including the relevant ways with "from" and "to" roles.
> > 
> > This was my best guess from what I could find on the wiki.
> > 
> > Is this the right way (in the UK)? Or will it be interpreted as
> no-entry
> > for all vehicles by routers?
> 
> I mapped a road which had different maxweight restrictions depending
> on which way you entered it:
> http://www.openstreetmap.org/browse/way/55165330
> I used maxweight:forward and maxweight:backward based if I remember
> correctly on IRC discussion and this wiki page:
> http://wiki.openstreetmap.org/wiki/Forward_%26_backward,_left_%26_ri
> ght
> 
> No relations needed. In your case you would only need to tag either
> forward or backward depending on the way direction.

That's useful. But in my case, there is another junction half way
along with no signs, so presumably there is no restriction on
vehicles "maxweight:forward" if they enter from that point. 
The only thing that is clearly signed is turning into the road
from one end. Everything else is ambiguous: there is no indication
of how far the restriction applies. So in this case a turning
restriction and thus a relation seems like the right solution.

I am just worried that the tag
 restriction = no_entry
may be seen by routers without the qualification of the other tags,
and so interpreted as banning all vehicles.

I am inclined to invent
 restriction=no-entry:maxweight
but that is really duplicating 
 type = restriction:maxweight.