[Routing] Leave motorway, turn onto track

[Ralf Zimmermann]

The situation near the hamlet Arispe that David points out is even more 
complicated.

The residential way that crosses the two motorway lanes does not have 
nodes at those crossings. The ways are only crossing on the data layer, 
but they are not connected. So a routing engine would never try to route 
between that residential and motorway highway:

http://yournavigation.org/?flat=31.1513&flon=-105.276856&tlat=31.152765&tlon=-105.273815&v=motorcar&fast=1&layer=mapnik

In real life though I guess that it is perfectly legal to exit and enter 
the motorway at that residential road. That is how it works in the more 
"lonely" parts of the US...  ;-)

In this case, the road in question is residential. But I guess similar 
situations exist for crossings between motorway and track.

So I think if we sometimes need to disallow turnings of this kind (if 
there would be the necessary nodes...), we need to set turn restrictions 
or tags manually.

This would be true in Germany, where often service roads connect to the 
motorway. But those roads then typically have a sign forbidding 
exit/entry for normal users. So I would set appropriate tags here.

To me, these case studies show that an automatic disallowing of 
exit/entry on motorways might be creating more manual work than it 
actually saves.


Ralf
Munich, Germany


David Lynch wrote:
> This needs to be set with turn restrictions or permissions on the
> track. There are places in the western US where there are legal turns
> directly from a motorway onto what would probably best be classified
> as tracks, including a few actual crossroads, such as at
> http://www.openstreetmap.org/?lat=31.1514&lon=-105.2699&zoom=14