[OSM-newbies] highway=traffic_signals

[James Ewen]

On Sat, Apr 10, 2010 at 1:14 PM, Dave F. <davefox at madasafish.com> wrote:

> Right, OK, let me clarify my understanding of traffic lights. The nodes
> I place represent not only the actual lights but also where the vehicles
> are meant to halt. I see it as a type of barrier.

Okay, where do I put the nodes for this intersection? http://tinyurl.com/y9cut6x

You'll notice that the traffic signals are on the far side of the
intersecting roadway, and the stop line on the close side of the
intersecting roadway. Do I put the traffic signal node at the location
of the light, the location of the stop line, put a node at each, or
split the difference and put it at the intersection being controlled?
Also notice that there are horizontal and vertical signal on the
poles. The horizontals control through traffic, while the verticals
control the left turning traffic.

What about this situation where the signals for both directions are on
a single pole? http://tinyurl.com/y9pdbaa
The traffic approaching from where the camera is situated has to stop
about 40 feet short of the intersection where the signals are still
visible. The opposing traffic stops right close to the intersection,
as the lights are on the opposite side of the intersection.

Putting nodes where the signals are located will be a problem when the
signals are located beyond the intersection. If you're going to
micro-map, I would think that you're going to have to map the location
of the traffic signal, the location of the stop line, and the
direction of the way through intersection being controlled all as a
relation, and then multiply that by the number of signals in the
intersection.

I don't know if you can partially micro-map successfully. If you're
going to try and describe the location of part of the signals, I would
think you'd have to do it all.

By just putting a node on the intersection, you are stating that the
intersection is controlled by signals. Granted, there are still
problems with that, which is apparent when you look at something as
simple as the intersection of 2 dual carriageways.

Perhaps if you can explain your concepts, we might find a better way
that might be a mix between the two extremes.

James
VE6SRV