[Talk-GB] Traffic lights

[Richard Bullock]

>
> I'm of the school of opinion that places bus stops to the left/right
> of the way but for traffic lights I do exactly what you do.
>
> - It is easy to enter and render
>
> - It is easy to extrapolate backwards, i.e. one
> highway=traffic_signals on the intersecting node equals one light on
> each way coming into the node (even taking into account they may be
> one-way).  There is no practical need to know which side of the road
> the lights are(?). I'd be happy to mark lights individually if I find
> a special case, but I haven't yet.
>
> - It is adequate for routing (?), i.e. if a way has a traffic_signals
> node on it, add a penalty.
>
> - For routing, if there is a left filter without a light, then I draw
> a small connecting way short-cutting the lights node.

That seems reasonable to me. I normally place a single 
<highway=traffic_signals> on the node of intersection.

I have found some special cases - e.g. where a road narrows to cross a 
bridge or go under a tunnel - and traffic flow is controlled by having a 
traffic light at each end - e.g. this one either side of a narrow railway 
bridge near to Chelford in Cheshire.
http://www.openstreetmap.org/?lat=53.2774&lon=-2.26827&zoom=17&layers=0B00FTF

I'd be interested to know if anyone would tag that differently - given that 
the traffic signals point in one direction only.