Comment by shaftway
8 hours ago
How large is too large?
I'm American with a roundabout very close to my house. The inner radius is 10 meters with an island in the middle, and single lanes in all directions. I have witnessed it successfully navigated at well over 100 kph.
Also, it's not a speed thing. I've seen this at another roundabout near my house. There's a school dropoff near it, so in the morning traffic backs up through the roundabout onto one of the entrances. The rules are that traffic in the roundabout has the right of way, so nobody lets anyone from one of the side streets in.
I guess I'm not a traffic engineer. And there are of course humans-doing-crazy things. But the roundabouts in my neck of the woods are a lot more reasonable. Sure, there is the occasional timid driver who can temporarily gum up the work. I can't say I know if it is the drivers or the roundabout design, or what that would make roundabouts useful in some areas and less useful in others. I bet it would make a good YouTube video if someone were to critique one of the unsuccessful roundabouts (or at least I'd give it a click). And if someone is looking for YouTube video opportunities, it would also be interesting to see how Tesla FSD handles this. Line up 10 or 15 going in one direction, and another 1 or 2 in the perpendicular direction.