We have a few 6 lane (and a bunch of 4 lane) roundabouts and rotaries here in Metro Detroit with more on the way. There is one area where two or three communities have a whole bunch of the roundabouts in close proximity to each other on some heavily trafficked roads and when they first started putting them in, everybody found something to complain about but eventually people got used to it. I cannot remember if the number of accidents actually decreased but I know that the severity of accidents is significantly less because everybody is (hopefully) moving in the same direction and at continuously similar speeds so there should be no head-n or t-bone accidents.
The one problem that we did run into after they were put in is that the engineers don't want to put in timed crosswalk signals because that stops traffic flow, which goes against the entire concept. So for pedestrians, not only does traffic not stop, but because of the design they often have double the number of lanes of traffic to cross. IIRC, the communities did finally convince the road commission to add HAWK Beacons to some of the crosswalks that have heavier pedestrian traffic.
We also have a diverging diamond interchange where an interstate, a major highway, and a major arterial street all come together. That one was pretty crazy but it really does help the traffic move.
We have the most mucked up traffic circle (calling it what it is, trending names aside). Depending on where you enter, either the existing circle traffic has the right of way and entering traffic has to yield, or the other way around. It's just st00pid.
I've seen roundabouts in Europe that are traffic light regulated and still deliver efficient traffic flow; the one near us needs that kind of treatment I think.
We also have a diverging diamond interchange where an interstate, a major highway, and a major arterial street all come together. That one was pretty crazy but it really does help the traffic move.
From a Planner perspective, I suppose I get the concept behind these but in real life, I just can't wrap my head around it. There are some in ATL. I hate them.
From a Planner perspective, I suppose I get the concept behind these but in real life, I just can't wrap my head around it. There are some in ATL. I hate them.
I think I looked at it opposite as you did - on paper, I just don't get it but the first time I drove through it I was amazed at how well it functioned and how everybody moved through so seamlessly.
There was one proposed at my last job. It took me a while to understand it, but it's supposed to flow extremely well. I've just never actually seen one.
