[talk-au] Traffic Signals

[David Murn]

On Fri, 2010-03-12 at 09:52 +1100, Steve Bennett wrote:

> Put it this way: how would you render a single circle for any
> intersection that has a traffic light? That is, if there are traffic
> light nodes at one intersection, you still only want to render one
> circle. It's a pretty obvious use case.
> 
> How would you count the number of traffic lights along a given route?
> The scheme that's been described here would return double the actual
> number.

One thought that has been proposed here before, is adding all traffic
lights at an intersection to a relation.  That way, you  simply count
the number of traffic light relation groups along the way rather than
the number of nodes.  This means if you have two junctions close to each
other in distance, but that are physically separate traffic light
controls, that youd add each light of each group to 2 different
relations.


> Perhaps we want to distinguish between an "intersection with lights"
> node and an "actual traffic light" node.

The problem here, is that if you have an 'intersection with lights' that
doesnt necessarily affect all ways going through the intersection.  For
example, some roads have traffic lights  on the slip-lane where others
dont, and as I mentioned in my first email, you also have to allow for
the crossing=traffic_signals node used between foot/highway
intersections.

David