[talk-au] traffic lights on dual carriageway intersections

Ian Sergeant inas66+osm at gmail.com
Sun Nov 4 11:07:30 GMT 2012

On 4 November 2012 20:58, Ian Steer <iansteer at iinet.net.au> wrote:
>>>>> By choosing to place traffic light not on the intersection node, you
> are failing to represent that "this is an intersection of two roads,
> controlled by traffic signals".
> I don't see how it is failing to represent that - the intersection is there
> (the ways intersect at nodes), and there are traffic signals *before* the
> intersection (not smack-bang in the middle of the intersection)

Because our current schema indicates that an intesection is controlled
by signals by placing the traffic signals on the intersecting node.
Traffic lights do occur before intersections or the immediate vicinity
without controlling traffic movements through that intersection.

It is a meaningful respresentation.  In many North American cities the
signals hang right in the centre of the intersection.  Are you saying
these should be mapped differently just because the lights are located
in a different location?  As far as the road user is concerned, they
are the same.  They don't care where the traffic signals are - they
care there are lights at the corner of 6th and Vine.

> - and if we were REALLY keen, the same *could* be done for single carriage
> way intersections (but I'm not suggesting that that is a sensible option)

Exactly.  This is the clincher.  Why on earth would you develop a
schema that is only relevant to dual carriageways?

When there is a schema that can respresent stop lines, signal
locations, and intersection control across all junctions then I'm in.
Until then, trying to vary the current schema in a way that is both
ambigious, and only works for dual carriageways just doesn't fly, IMO.


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