[OSM-newbies] highway=traffic_signals

[James Ewen]

On Tue, Apr 6, 2010 at 8:54 AM, Xan <dxpublica at telefonica.net> wrote:


> Or where the light signal, isn't?
>
> So, I have to fix some traffic:signals:
> http://www.openstreetmap.org/?lat=39.551131&lon=2.620521&zoom=18&layers=B000FTF

That looks like a problem area that is under discussion...

http://wiki.openstreetmap.org/wiki/Proposed_features/Set_of_Traffic_Signals

At a simple intersection, when two single ways intersect, a single
node defines the intersecting point, and that should be tagged with
the traffic signal. Even though there may be 4 poles holding the
actual light hardware, the traffic signals control that single
intersecting point.

Think of it from a routing engine perspective. The computer is
basically running it's digital finger (ha, I made a funny) along the
line that defines the road. When it gets to the intersection, it
notices that there is a traffic signal associated, and might make a
note of that (taking into account that the light may impede progress,
or maybe tell the user to "Turn right at the traffic signal").
However, if the routing engine is running it's finger along the way,
it's not going to be looking for things tagged along the side of the
road. If the traffic lights are tagged as independent nodes beside the
way, how do you know that the independent node is associated with the
way?

In the same light, there are bus stops tagged along the side of
Rotherham Road. The bus shelter/bench is physically located at that
location, but one would think that the bus stop node would be
associated with a bus route, rather than an independent node beside
the roadway.

These are little issues that make making a map so much fun!

James
VE6SRV