[Routing] [motorway_link] description of direction

[Nic Roets]

On Mon, Jun 16, 2008 at 1:58 PM, Jon Bright <jon at siliconcircus.com> wrote:

> I've changed via from node to way because there may well be no "forking"
> node which is unique to the route being travelled.  Intermediate nodes
> which only have two connections will, I imagine, frequently be ignored
> by routing software, as they're not relevant to the calculations at
> hand.  Whereas two different ways to do the same thing implies a fork,
> which implies two different way IDs.

I may not understand you correctly.

My understanding is that the 'via' node will always occur in both the
'from' way and the 'to' way.

The difficult case is http://www.rational.co.za/routeRelation.png
All 3 ways are bidirectional. If the computer wants to route you from
the gray way to make a left turn (with or without reaching the green
way) it needs to be able to reliably detect which relations to use.

The best way will be if the via is a node and we have a tag specifying
left or right turn, like the turn restriction has the 'restriction'
key. And the closer we can bring these relation templates together,
the better.