141 roundabouts overall in Carmel! Wow. I used to live in northern Indy and I had no idea. But then, Carmel is where all the rich basketball and football players, and doctors, lived.
There’s another 140 or 150 in the other northern suburbs (Noblesville, Fishers, Zionsville, Westfield) combined.
And still half the drivers are completely flummoxed when they get to one. My wife was just side-swiped two days ago on a Carmel roundabout.
Oh for Pete’s sake. Wasn’t until I looked at Fleshman & 5th on GMaps that I recognized the one you mean. Forehead slapping moment- I’ve driven through that one several times just weeks ago. I’m quite comfortable with roundabouts but always find this one odd.
You know, the words will make you out and out.
“Double roundabouts” - which appear to the same thing or at least highly similar - are common in Cornwall, in SW England.
Here’s one.
I think of roundabouts as appearing in the UK before most other places, but as for this specific type of junction, I have no idea.
j
They’re similar, but not the same.
The modern roundabout was, in fact, invented in the UK, in 1966. The US didn’t build any until 1992 and they really didn’t take off here until about 10 years later. So Britain had a 30 to 40 year headstart on building them. Which is why they’re everywhere there and relatively few here. France, BTW, has even more roundabouts than UK, but that’s mostly because it’s a larger country.
Aside from geometrical issues, such as offset/angled cross streets, they were mainly developed for highway interchanges since they need only one bridge and can be more easily retrofitted into an existing footprint. Think of them like a full circle where the middle has been pinched together, eliminating most of the dead space inside. Doing a full circle with two bridges is certainly possible, but it runs the risk of the circle radius getting too large, which increases speeds and reduces capacity and safety. That’s a big reason why older (pre-1960s) traffic circles and rotaries perform poorly, the higher speeds means entering traffic needs longer gaps between vehicles to merge in.
Like I said, I live in Indianapolis - I regularly encounter them, as Carmel, IN and its 10+ peanut roundabouts (and 140+ regular roundabouts) are just a few miles from my house. I’m not asking why they aren’t full circles - I’m asking why they aren’t just ovals (or rather, 2 half circles joined by 2 straight-aways). I believe dtilque answered that.
[Forgot to reply to this one earlier.]
It was on the list because the list includes those under construction. I sent it in in late November before it was completed.
Looks like it’s missing the new ones under US 31 in Carmel, they’re at 106th, 116th, and W. Main St.
The list (and me) makes a distinction between peanut and dogbone roundabouts. The main thing is what the roads connecting the two lobes do. If the roads come together and make a short two-way road, they are dogbones (or dumbbells). If they just curve in somewhat and then curve out, they’re peanuts. Admittedly, there are some edge cases, but usually there’s no problem telling the difference.
I just looked at those three on StreetView and they are definitely dogbones/dumbbells.
We have a Dogbone at I295 Exit 22. The straight section is an overpass. Nobody goes all the way around either end, they’re there to facilitate left turns. It’s also a modern tragedy, years of construction, millions of dollars, thousands of lives… wait, no lives yet, but still wasteful for an intersection that needed a couple of lights that could be blinking yellow except for an hour and a half in the evening rush hour.
Do you know the crash history at the interchange? It’s quite possible that it has a history of frequent crashes. After all, that’s the primary reason they choose to put roundabouts at a given intersection. Long traffic backups are a secondary reason.
I don’t recall any in nearly 30 years before this was built. Certainly no more than a fender bender. A couple of those since construction completed. There is no significant traffic there except during the evening rush hour and it’s done little to help with that. This was just a bad idea and an excuse to spend federal money. A pair of lights allowing left turns during the rush hour would have solved the only traffic issue.
There’s one near Brighton, MI. https://maps.app.goo.gl/zkYRowq7AaXaCMkV8
Just ran across this very interesting video of the history of the roundabout and why we don’t have as many in the US. Produced by CNBC.
Does this one in Mooroolbark, Victoria, count?
(and is it actually a double peanut?).
I guess I haven’t been as clear as I should have been about what is a peanut roundabout. It’s a two-lobed roundabout where neither lobe is a complete circle. Instead the road just makes sort of a figure-8 shape, where the two sides either don’t touch or just touch at single point. The term “pinched roundabout” used by a site linked upthread is fairly good description. You take a circle and pinch is so it bulges out on either side, but don’t pinch it so hard the middle becomes flat.
Anyway, it’s not just two circles in close proximity, which is what the above contributions are.
Fair enough. In that case, I’ve never encountered a true peanut.