[OSM-talk] Traffic lights

[Peter Miller]

On 13 Jun 2009, at 16:36, Cartinus wrote:

> On Saturday 13 June 2009 16:34:48 Polderrunner wrote:
>> I'm also in the
>> "life-is-too-short-for-complex-mapping-of-traffic-lights" camp.  
>> However,
>> to provide routers etc with a realistic view of the intersection I  
>> put
>> the 'outer' traffic lights at their real position before the junction
>> nodes (and also before any crossing cycleways). I don't put any
>> 'interior' traffic lights. Example:
>>
>> http://www.openstreetmap.org/?lat=52.04246&lon=4.32104&zoom=17&layers=0B00F
>> TF
>>
>> A router will only see one traffic light whatever direction is chosen
>> through the intersection. This would be realistic for most  
>> intersections
>> having synchronized signals. And the extra effort is minimal.
>
> I've thought of doing it this way too for intersections of two dual
> carriageways. With two intersecting single carriageways I'd put the  
> traffic
> lights in the single intersection node.

With this approach you are effectively encoding the stop line  
associated with the traffic signal into the model which is certainly  
an approach however the renderer is still going to want to know about  
junctions and dual carriageways in due course for better rendering a  
lower zoom levels.

I am not convinced by the 'I haven't got time' argument. In your  
example one could probably encode it using the junction relation in  
about as much time as adding the four nodes and there is more benefit  
from doing that in the longer term by providing the higher level model  
of the junction (ie "these roads here are part of a junction, there  
are four dual carriageways approaching it and it is traffic signal  
controlled so feel free to render it as a four single ways coming to a  
single node if that is what you prefer").

Regards,




Peter


>
>
> The problem I have is, that I don't know of a way to avoid "passing"  
> an extra
> traffic light for intersections of a single and a dual carriageway.  
> Does
> anyone know a solution for that?
>
>
> -- 
> m.v.g.,
> Cartinus
>
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