On Wed, Oct 23, 2019 at 5:06 AM Florian Lohoff <[email protected]> wrote: > On Wed, Oct 23, 2019 at 12:00:13PM +0200, Tom Pfeifer wrote: > > On 23.10.2019 11:35, Florian Lohoff wrote: > > > > These are a very common feature, it does seem odd that routers are > not supporting them. > > > > > > The point is that a mini roundabout does need a LOT of preprocessing to > > > put it into some graph for your classical A* or Dijkstra. You need to > > > eliminate the node and replace it with a circular road much like a > > > junction. > > > > Could you explain what the preprocessing is needed for, and why you need > to > > replace it in the routing algorithm. > > > > From my perspective nothing is needed. The routing engine recognises from > > which way you come and where to leave, and, since the feature is so small > > and clear, it can give instructions like at a normal junction, just using > > the tag to describe the junction: > > "At the mini-roundabout [turn right|go straight|turn left]". > > You would expect (as you see a roundabout sign) to get instructions to > take the n.th exit. >
At a mini roundabout? I mean, for all five of 'em we have in the US so far (three of which are blocks apart from each other in a city near me, basically the same thing as the UK version but turns the opposite direction and has a decorative brickwork or orange island instead of a white one), no, not really, I'd just expect to be told which way to turn and that it *is* a mini roundabout. The only thing I might do differently than a regular junction would be a straight through movement, have it pipe up to say "at the mini roundabout, continue straight on." This largely to tell me the two things I need to know offhand at such a junction: Turns work backwards than normal and all four ways yield to people in the intersection, otherwise roll it, so I can expect people to stop but can't count on it if I get there first. > The roundabout change which triggered this mail is MUCH larger - And you > physically can go straight but there is a small curb - so cars will use > the circular road, trailers will possible use the curbed center with the > last axles. > Could we get a link to this roundabout? Seems like a potentially difficult call, mostly because the only difference between a painted on median and an all-"truck apron" median is basically like going over a driveway curb cut and not a physical barrier. > > Basically the mini-roundabout is effectively more about who has priority, > > and here all incoming roads have to 'give way'. Similar a four-side > "stop" > > sign in the US. I have used them in Britain and they are often just a > bucket > > of white paint poured in the middle of a junction. > > A mini_roundabout has the same rules as normal roundabout from what i > look at the definition. The only difference is that its physically > traversable. > This differs from an all-way stop, which is just bad engineering for stupid people by lazy traffic controllers.
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