[Talk-GB] Traffic lights

[Michael Collinson]

At 12:52 PM 9/15/2008, Ed Loach wrote:
>Is there any concensus on how to mark traffic lights? I've been 
>marking the nodes where two ways join at a light controlled junction 
>as traffic_lights, based on where I first saw them used elsewhere, 
>but I have since discovered that in some locations some mappers try 
>and mark each traffic light post with it's own node (which can make 
>a junction look a bit cluttered when rendered).
>
>I guess technically you are unlikely to get a set of traffic lights 
>positioned in the centre of a junction, but in my opinion it is more 
>of a property of the junction than an instruction to render lights 
>in the centre of the junction.
>
>Any opinions either way (at the risk of split opinions along the 
>lines of bus stops)?

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.

Interested to see counter-opinions,
Mike