At the risk that we are going in circles on this argument. Let us try to figure out what the needs are.
What we have (in theory) at present is - a roundabout is a road layout where traffic goes around a central island. At present a roundabout needs to be drawn as a circular way, not as a node. The direction of traffic depends on the country (left-hand or right-hand drive) - a mini-roundabout is a road layout where traffic goes around a central traversable area. This is to allow long vehicle to use it. A mini-roundabout is inserted as a node, not a way. The distinction between the two types of roundabout is clear-cut in some countries, where there are different rood signs for the two types, and is less clear-cut in others where the same road sign are used for both, only the physical implementation is different. Where does our problem stem from? Many mappers have used the mini-roundabout node for physically small roundabouts with an non-traversable centre island. In some cases (I have done it myself) it has been used to mark even a larger roundabout in a provisional way. What we are missing in this scheme is most obviously a “roundabout” node. Let's look at the new roundabout node: We should give it parameter to indicate its size, for example est_diameter. Now we have to consider the routing: If we look at the end product we want be able to deliver, i.e. the vocal instructions, they would have to distinguish between two categories of roundabouts: - “small” roundabouts, i.e. mini-roundabouts and roundabout nodes with est_diameter less than 12 meters (tbd): “turn left”, “turn right” etc - “large” roundabouts that are drawn as circular ways and node-roundabouts with est_diameter over 12 meters (tbd): “enter roundabout”, “take third exit” etc. So, if we look at it from the routing point of view it looks to me that we do not need to distinguish between a mini-roundabout and a small roundabout, but what we seem to need is a way to indicate the size of the roundabout in order to distinguish the routing behaviour. What I am arriving at is that we need a new node “roundabout” with a mandatory size parameter of some kind. The distinction between the present “mini_roundabout” and a small roundabout would no longer be relevant. Volker
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