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Generalising for all roundabouts, I propose a model in which there are three diameters:
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D1) outer diameter, where the outer kerb is
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D2) "guide" inner diameter, the outer diameter of the inner ring intended to "discourage" traffic
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D3) inner diameter, where the inner kerb or wall is (not traversable)
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A mini-roundabout with no central obstruction will have D3=0 but may have D2>0 (possibly 1m-3m)
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A normal UK roundabout will not use D2
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A form of roundabout common in the Netherlands has an inner ring which is often distinctly coloured and slightly raised, thus making it clear that traffic is intended to avoid it and use the outer ring, while keeping it perfectly usable by most vehicles.
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Example: <a href="https://nl.wikipedia.org/wiki/Rotonde_(verkeer)#/media/Bestand:N746-Noordergraafsingel-Harbrinkhoek.jpg">https://nl.wikipedia.org/wiki/Rotonde_(verkeer)#/media/Bestand:N746-Noordergraafsingel-Harbrinkhoek.jpg</a>
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These numbers can be used for simple navigation instructions as has been mentioned. But they could also be useful for route planning for oversize transports: can they make it around/across, given the available road width and the geometry of the turn they want to take?
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Generalising further could replace circles and their diameters with concentric polygons to allow for odd-shaped roundabouts, but that might be a bridge too far at the moment?
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On 28/01/2023 22:12 CET Philip Barnes <phil@trigpoint.me.uk> wrote:
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</div> Diameter implies there is something circular. The paint is often round, not always, but most are just former T junctions or cross-roads where there is nothing to measure the diameter of .
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<br>Phil (trigpoint)
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On 25 January 2023 17:50:54 GMT, Volker Schmidt <voschix@gmail.com> wrote:
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Is there an established way to tag the diameter of a mini-roundabout?
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We have the tag diameter, but I could not find it applied to mini-roundabouts.
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