4-way STOP v. Roundabout efficiency - by the Mythbusters

[froggie]

Well, that means we won't see mini-roundabouts in the US!

Too late.  Swing through Manchester, VT on your way back from Burlington for an example.

I don't think it's even physically possible for American cars to avoid the dot.

It's possible for American CARS (even a minivan).  It may not be possible for American DRIVERS.

[KEK Inc.]

Mini-roundabouts are everywhere in Seattle and Portland.  They're old as shit too.

[Indyroads]

https://maps.google.com/maps?q=butternut+and+lichen+citrus+heights&ie=UTF-8&hq=&hnear=0x809adf826ac66cd7:0xefdf7c0fc141486b,Butternut+Dr+%26+Lichen+Dr,+Citrus+Heights,+CA+95621&gl=us&ei=63w7UsCzEOeEygHkkYDYCA&ved=0CCkQ8gEwAA

Here's another mini roundabout built into a Citrus Heights intersection.

[andy]

Not directly "efficiency" related, but just coincidentally, my home town (Madison, Indiana) is looking to add a roundabout at a troublesome intersection;

http://madisoncourier.com/main.asp?SectionID=178&SubSectionID=963&ArticleID=79058

According to Maurvick, 38 percent of the accidents at the intersection are considered severe accidents, or accidents that involve an injury.

According to Maurvick, that's because the accidents frequently happen at a 90-degree angle. A roundabout, he said, reduces the opportunity for 90-degree collisions. Instead, vehicles are more likely to side swipe one another in a collision.

"You have a much better chance of walking away from a 20 mph sideswipe than a 50 mph T-bone," Maurvick said.

I'm pretty sure this is still a four way stop which too many drivers don't seem to notice until too late.
Fortunately (??), they just built the new hospital a quarter mile away.

[Aerobird]

Mini-roundabouts, you say?

Circle Drive and Alban Avenue in Tallahassee - no driving over that "dot". And it used to be just a little concrete pillar in the middle of the intersection!

Or this one, one block to the west at Circle and Seminole Drive.

[Indyroads]

this begs the question... How many people just ignore the glorified planter island or painted dot in the center of the intersection and just make a left turn (on the wrong side of the island) anyway because they are lazy or just don't care? And would a cop really make a big deal of it?

[mrose]

During my 7 years in Australia I got pretty familiar with them.

Small roundabouts that replace 4-way stops: I loved them. If the thing is empty, you just plow right around it without stopping, which is a big plus.

However, I hated the large multi-lane setups, especially when there were multiple spokes. There were parts of Melbourne that had maybe five or six points coming out with two and even three lanes in the roundabout, and I found those to be quite intimidating.

So I've tended to form the opinion that the one-lane variety is superior, but the multi-lane variety is not.