I lived in Swindon
The signs leading up to it make it look like a big swirling hurricane surrounded by five little hurricanes. The “magic” is you can go counter-clockwise (the correct American way!) should you choose, by taking each little pin-wheel roundabout .
However, you can traverse the thing like a regular roundabout on the outside. During rush-hours it’s a rather lot of traffic so if you can figure out a clever strategy this too is part of the magic.
So why is our Dogbone double roundabout significantly different from a Peanut? The constriction between the circles is simply an overpass (RI114 crossing over I295), there are no central turns and the lanes are separated. It does stretch the shape out because of the length of the overpass. This Dogbone was built around the existing overpass. You can see how the shape was constrained by the nearby streets, homes, and buildings, plus open space needed for drainage areas. So this seems to be the only possible way to put this kind of interchange on the available land.
It’s a definitional thing. But those lanes aren’t separated by all that much, less than a lot of boulevards or streets with a central turn lane. Anyway, dogbone and dumbbell roundabouts are actually quite common at freeway interchanges. If those were all included, the list would be ten times its current length and much more tedious. Peanut roundabouts are interesting in part because they are rare.
I am a little late to the party and very new here (my first post).
Someone asked why dog bones are shaped the way they are. It is to reduce speed but in Carmel, where they act as overpasses, it also narrows the width of the bridge and reduces cost. One bridge is cheaper than two.
I also wanted to link my site, which lists every roundabout in Carmel (157 so far). Each with their own page of photos. I recently added a section for the other roundabouts in Hamilton County (144 so far). I have found three roundabouts that date back to the 80s (pre-Brainard) that Carmel doesn’t even recognize on their list of roundabouts.
Welcome!
If you like yabbering on about obscure things, this place is probably for you.
Welcome to the Dope, as we sometimes call it.
There’s two ways to handle roundabouts at freeway interchanges. One is a dogbone/dumbbell roundabout, the other is a single roundabout that sticks out on either side of the freeway. Yes, the second requires two bridges or a single long bridge and that’s expensive. OTOH, the dumbbell takes up more land area, which can also be very expensive.
Dumbbells/dogbones are very common in the US and Canada, while the second type is actually more common in Great Britain. I attribute this to the fact that GB started building roundabouts in the mid-1960s, about the same time that freeways (OK, motorways) became common. So they were mostly building them together. I expect it wasn’t quite as expensive to build a larger bridge than to acquire the additional land.
In North America, roundabouts at freeways are virtually always a retrofit. The bridges are already there, so they have to work around that. So two roundabouts on either side of the freeway would be much cheaper than rebuilding the bridge.
Awesome site, dude. I notice you have a link to the Kittelson database. Do you contribute to that? I’ll confess that I’m a major contributor there.
I don’t have an account with the Kittleson database but I did send in the nine or so Carmel roundabouts they didn’t have a record of and those have now been uploaded.
Good enough. I will note that the link at your site could be a bit better. It goes to the result of a search for “Carmel” in the database. However, the search also picks up entries where the word “Carmel” shows up in other parts of a record, such as the name of a street. Which means it returns 166 entries instead of just the 157 that are actually in Carmel. Unfortunately, there’s no way to specify that you only want to search on the name of the city in a search.
However, as it turns out, all those extra entries are in other states. If you modify that search to specify the state as IN, you will only get those entries from Carmel IN. Here, I’ll do the search for you. Just copy this link:
If I type in the Quick Search “Carmel, IN” it has always and still comes back with 0 results for me. Never understood it. Figured it was a bug or some sort.
I did copy your link over though. Not sure why it works for you but not me. I also have the database linked individually for each Carmel roundabout on my list. If you click the year the roundabout was built it links to the database. It you click the street names it goes to the pictures on my site.
Edit: Nevermind. It works it Advanced Search. I had always tried it in Quick Search with no success. Thank you for the direction.
If you go to the Advanced Search page, there’s a separate field for selecting the State/Province. Enter “Carmel” in the Text Search and then select IN (type an I multiple times until IN comes up).
ETA: didn’t see your ETA.