I’m trying to find where and when the first peanut roundabout was made. For those unfamiliar with them, peanut roundabouts are a two-lobed roundabout that makes a figure-8 pattern. They are not very common, but here’s a list of known peanutabouts:
I’ve looked up all of those on Google StreetView and found there’s only a couple I can’t date: the one in Dartford, England and one in Warrnambool, Victoria, Australia. The earliest images of those on StreetView are from 2008. But StreetView only goes back to 2007, so those likely were built significantly earlier. And neither one is probably the first. The list is by no means exhaustive of all peanut roundabouts.
Anyway, asking here is kind of a long shot. But if anyone knows of a peanut roundabout not on that list, let me know.
@mixdenny is our resident expert in sleuthing out old images of how stuff used to look. Once you find one of interest he’s probably the best bet on dating it.
Definitely not. Way too old. A peanut roundabout is form a regular modern roundabout. The modern roundabout was only invented in 1966, so the first peanutabout would have been built sometime after that. Probably a fair number of years later.
A modern roundabout is a way to have a intersection of roads where the cars don’t necessarily have to come to a complete stop, but (and this is the important part) they are forced to slow down. Previous circular intersections (rotaries) allowed at least some vehicles to go through without slowing down. That turned out to be a bad idea.
The thing in roundabouts that slows the cars is to have a fairly small circle where the vehicles are always turning. The older rotaries were large circles where the turn radius wasn’t small enough to force a slowdown. Roundabouts are smaller so do force a slowdown. But what do they do when the roundabout needs to be longer in one direction? For example, to accomodate two nearby intersections. If they put in a racetrack oval with straight sides, cars will speed up on those straight sides. So they put in curves going inward and then outward along those sides and it comes out as a figure-8-ish shape.
Anyway, the two that I don’t have a good date for are in Dartford (lat/long 51.43812, 0.25440) and Warrnambool (lat long: -38.37741, 142.47912). Or if someone knows of another old one, probably in either UK or France, let me know about it.
Not sure they are exactly “peanut” roundabouts, but I know of two that I have heard referred to as “dogbones”: One in Clarkston, WA and the other in Kennewick, WA.
Dogbone (and dumbell) roundabouts are somewhat similar to peanut roundabouts but not identical.
Dogbones and dumbells are two full roundabouts connected by a short straight road. The difference is that dogbone roundabouts are in a teardrop shape, so they don’t let the vehicles go in a full circle. When they get to the pointy part, they have to exit to the other roundabout. Dumbells have a full circle roadway. These two types are most commonly found at freeway interchanges with one circle on either side and the short road going over or under the freeway.
Checking the map, Clarkston has a dumbell and Kennewick has a dogbone at freeways.
I gotta say that I don’t really understand the peanut roundabout. I live in Indy, so I’m well-acquainted with them - but I wonder why the middle of the roundabout needs to curve inward. Is it simply about traffic control so that there isn’t a small straightaway to increase speed?
(Roundabouts are really numerous in the area - I didn’t particularly love them until somewhat recently. For Christmas, my wife got me a small painting of one from an artist friend of ours. I love it.)
Basically, yes. Also cuts down a little on the cost of land, which is often the biggest cost in development.
Especially in the northern suburbs, which contain Carmel, the most roundabout-intensive city in the country, possibly the world. But there’s also a bunch in nearby suburbs, not very many in Indianapolis itself.
I can’t find any older aerials or topos at those two places. I’m pretty much a US guy. However I will note that they just opened one near my home on Mill Rd in North Ridgeville, Ohio. It has been in the news a few days ago. Amazingly it is already on that list! I haven’t been there yet but I will try it this week. Local reaction is very positive. The sight lines were terrible in one direction and there had been numerous accidents.
dtilque already provided the details on the Clarkston dogbone. It only went in a couple years ago and I think it is fantastic. We go through there a few times a year on our way to outdoor opportunities to the south.
We lived in Moscow for a bit while I worked and took some classes at UI.
Castle Hayne, North Carolina at US 117/NC 133 (N. College Rd/Castle Hayne Rd) has one. Its Google aerial view was posted on SDMB by Ignatz several years ago.
There is an article about the A296 here, describing the history of the road and mentioning the “pinched” roundabout: A296 - Roader's Digest: The SABRE Wiki