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Comment by sokoloff | Hacker News Reader

Until you do what Cambridge, MA has done twice near my house: put a traffic light just outside the roundabout, so when the light turns red, traffic inevitably backs up through the roundabout, locking it up entirely.

https://www.google.com/maps/@42.3875777,-71.1422076,18z?entr...

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I can decisively say anyone advocating for roundabouts has not lived anywhere near Boston.

Let's be real, is this actually an indictment of roundabouts or is it just Boston?

Having lived in Boston and other areas with roundabouts, I can with confidence assert that this is a Boston traffic design problem, not a roundabout one.

note that proper spinlock procedure is to not leave the roundabout unless there is room to do so completely

this avoids complete deadlock until the entire roundabout is full of drivers who refuse to take any unblocked exit, while continually offering each the ability to do so

> not leave the roundabout unless there is room to do so completely

I don't understand how that helps. The problem is there are too many cars in the rotary, so no amount of not leaving the rotary will unblock it. It seems like you should not enter unless there's room to exit, but on some of these, you can't both see the exiting traffic light and safely merge into moving rotary traffic, so I don't really blame drivers who enter the rotary and find the light turns amber then red on them.

as an ai language model, i cannot speak to your particular intersection, but the idea is that if say just one car is waiting for the blocked exit, circling would allow other exits to continue to function, by following the general rule of 'do not stop once entering the roundabout'

i could also imagine that anyone waiting behind someone who is deadlocking might have success sending a signal to the blocking process, unless they have committed to a non-reentrant exit routine

They do that in Sweden all the time. I have no idea how a country that has some amazing minds can come up with the worst road infrastructure designs possible. Most of it’s unsafe so they just lower the speed limit.

The circles of death? :-)

I used to drive over there quite a bit. Always terrible.

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