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[BrianP]

Turning left at the green in front of opposing traffic was commonplace in MA when I was a kid, but the practice seems to be lessening.

Such is apparently called a Pittsburgh left. In my experience (largely in the West and South) I've seen it done on a few occasions, but almost always it just seems rude.

I've seen this happen many times here:
https://www.google.com/maps/@39.1707592,-77.2625327,3a,75y,325.28h,92.69t/data=!3m6!1e1!3m4!1sngd26qr69BlTaPiTR3z0cA!2e0!7i13312!8i6656

I haven't seen it anywhere else.  The only reason I think it happens here is the size of the intersection and the lack of a turn arrow.  But that's not unique.  But for some reason it happens there.  Like someone did it once and it caught on.  But not everyone does it. 

[MantyMadTown]

Are there any freeway roundabouts? I could see this concept work in rural areas with lots of room for a wide radius to keep speed. Would save on overpasses and flyovers.

not exactly, but close: NY85 - divided 4-lane 55 MPH, 3 roundabouts within 1 mile stretch.
https://www.google.com/maps/@42.6444845,-73.8563279,1384m/data=!3m1!1e3

Only 15 mph through the roundabout. Doesn't really feel close.

The closest I can think of to a "freeway roundabout" would be the large high-speed rotaries they have in the Northeast. I don't know specifically where they exist however.
I don't think freeways in the U.S. can legally have roundabouts or rotaries on their mainline. The definition of a freeway here means that it's controlled access, so the only way to get on or off a freeway is through on/off ramps. I could see two expressways having one (in Wisconsin they're defined as limited access).

I'm guessing that list came from this site: http://roundabout.kittelson.com/

It's cool to see them on a map.  You can also submit the locations that haven't been added yet.  (as far as I know all of them on there are just submitted by individuals, so certain areas may be more scrutinized than others)

I just submitted the planned roundabout in my hometown to the site. I don't know if they include ones that haven't been built though.

[kphoger]

Are there any freeway roundabouts? I could see this concept work in rural areas with lots of room for a wide radius to keep speed. Would save on overpasses and flyovers.

Though obviously not in America, the junction of the M1 and M50 on the north side of Dublin (RoI) was a roundabout with slip lanes until a 2008-2010 project made it free-flow.

[bcroadguy]

I guess this would kinda count as a freeway roundabout?

https://www.google.com/maps/@46.0974443,-64.7697549,15.72z

[jeffandnicole]

I can deal with roundabouts; it's the other idiots that can't seem to figure out how to properly yield that make them unpleasant for me. I have to pray that I don't get cut off from when another car approaches when I'm already in the roundabout.

Remember, if you feel that way about others, others are probably thinking the same thing about you as you approach a roundabout!

Ah, I see the warning signs now.

Technically, warning signs don't tell you what to do, just what to watch out for.  I'm struggling to come up with any guidance in the Illinois Vehicle Code on what to do at a roundabout or traffic circle, so it's possible it's actually a legal loophole.

I would think basic intersection protocal would apply (ie: keep right). 

Or, to think about it this way: If you turned left in front of the island, and another car hit you head on, would you think the car on the right (the one you hit) have the right of way, or would you (on the left) have the right of way?  That seemingly makes the answer much clearer.

[tradephoric]

I'm guessing that list came from this site: http://roundabout.kittelson.com/

It's cool to see them on a map.  You can also submit the locations that haven't been added yet.  (as far as I know all of them on there are just submitted by individuals, so certain areas may be more scrutinized than others)

That KML file i posted was created independently from that kittelson website.  Thank you for posting that link as i had never seen the kittelson database before.  It looks like a tremendous resource.  Within 10 minutes of looking through that website, i found dozens of examples of modern roundabouts that were not included in my database and vice versa.

[tradephoric]

^By the way, it looks like you can export the entire kittelson database into one large KML file if you click on INDEX and then the blue button that says "export as KML".  From there you can compare both databases together to see which roundabouts are potentially missing from each.

[vdeane]

I guess this would kinda count as a freeway roundabout?

https://www.google.com/maps/@46.0974443,-64.7697549,15.72z

Assuming one counts NB 15 there as a freeway.  Note the traffic light.

I already posted the other (much smaller) NB example in Fredericton.

[MantyMadTown]

I guess this would kinda count as a freeway roundabout?

https://www.google.com/maps/@46.0974443,-64.7697549,15.72z

That's a pretty big roundabout. Using the scale on Google Maps it looks like it has a diameter of roughly 1000 ft. It looks as big as the shopping mall right next to it. I wouldn't want to build such a big roundabout in the middle of any city.

[bcroadguy]

I guess this would kinda count as a freeway roundabout?

https://www.google.com/maps/@46.0974443,-64.7697549,15.72z

Assuming one counts NB 15 there as a freeway.  Note the traffic light.

I already posted the other (much smaller) NB example in Fredericton.

I just saw all the interchanges near it on Google Maps and kinda assumed it was a freeway for the most part / didn't notice the traffic light. Oops.

I saw the Fredericton example, but I thought I'd post this just because it's pretty big / relatively high speed for a roundabout (60 km/h limit inside the roundabout).

[bcroadguy]

I guess this would kinda count as a freeway roundabout?

https://www.google.com/maps/@46.0974443,-64.7697549,15.72z

That's a pretty big roundabout. Using the scale on Google Maps it looks like it has a diameter of roughly 1000 ft. It looks as big as the shopping mall right next to it. I wouldn't want to build such a big roundabout in the middle of any city.

And for such a huge roundabout, it seems pretty useless too. Judging from Google Maps, it looks like they could just get rid of it entirely and make all the traffic that exits there take the Paul St. interchange immediately east of it.

Edit: Didn't realize it wasn't a full movement diamond interchange, but they could easily convert it to one by adding signals on Paul St. / allowing left turns onto Paul St.

[jakeroot]

I guess this would kinda count as a freeway roundabout?

https://www.google.com/maps/@46.0974443,-64.7697549,15.72z

That's a pretty big roundabout. Using the scale on Google Maps it looks like it has a diameter of roughly 1000 ft. It looks as big as the shopping mall right next to it. I wouldn't want to build such a big roundabout in the middle of any city.

And for such a huge roundabout, it seems pretty useless too. Judging from Google Maps, it looks like they could just get rid of it entirely and make all the traffic that exits there take the Paul St. interchange immediately east of it.

Edit: Didn't realize it wasn't a full movement diamond interchange, but they could easily convert it to one by adding signals on Paul St. / allowing left turns onto Paul St.

As far as I can tell, the roundabout isn't there to facilitate U-turn movements for Paul Street, but to connect Wheeler Blvd with Route 15.

[kphoger]

Ah, I see the warning signs now.

Technically, warning signs don't tell you what to do, just what to watch out for.  I'm struggling to come up with any guidance in the Illinois Vehicle Code on what to do at a roundabout or traffic circle, so it's possible it's actually a legal loophole.

I would think basic intersection protocal would apply (ie: keep right). 

Or, to think about it this way: If you turned left in front of the island, and another car hit you head on, would you think the car on the right (the one you hit) have the right of way, or would you (on the left) have the right of way?  That seemingly makes the answer much clearer.

"Keep right" laws often have an exclusion for turning left and/or for obstructions in the roadway, but it doesn't matter anyway because I found the state law for roundabouts and traffic circles.

A vehicle passing around a rotary traffic island must be driven only to the right of such island.

[ScottRAB]

I guess this would kinda count as a freeway roundabout?

https://www.google.com/maps/@46.0974443,-64.7697549,15.72z

Traffic engineers classify circular intersections by diameter and traffic control.  That link would be a traffic circle, or rotary.
Many people confuse other and older styles of circular intersections with modern roundabouts. High speed, east coast rotaries, large multi-lane traffic circles (Arc D’Triomphe, Dupont Circle), and small neighborhood traffic circles are not modern roundabouts and UK 'roundabouts' are not the same as US 'roundabouts'.  The Brits even call a merry-go-round a kid’s roundabout.
What is, and is not, a modern roundabout:
UMass video:

WA DOT: 

NJ traffic circles: https://en.wikipedia.org/wiki/List_of_traffic_circles_in_New_Jersey
NJ wins award for building roundabout:
https://www.prnewswire.com/news-releases/national-roadway-safety-award-winners-announced-300556007.html

[ScottRAB]

They're all crash-prone.

Modern roundabouts are the safest form of intersection in the world - the intersection type with the lowest risk of fatal or serious injury crashes - (much more so than comparable signals).  Modern roundabouts require a change in speed and alter the geometry of one of the most dangerous parts of the system - intersections. 

The reduction in speed to about 20 mph and sideswipe geometry mean that, when a crash does happen at a modern roundabout, you usually need a tow truck, not an ambulance.  Visit the Insurance Institute for Highway Safety for modern roundabout FAQs and safety facts.  Roundabouts are one of several proven road safety features (FHWA). 
The life saved may be your own.
https://safety.fhwa.dot.gov/provencountermeasures/roundabouts/
https://safety.fhwa.dot.gov/intersection/innovative/roundabouts/

[ScottRAB]

Are there any freeway roundabouts? I could see this concept work in rural areas with lots of room for a wide radius to keep speed. Would save on overpasses and flyovers.

not exactly, but close: NY85 - divided 4-lane 55 MPH, 3 roundabouts within 1 mile stretch.
https://www.google.com/maps/@42.6444845,-73.8563279,1384m/data=!3m1!1e3

The point of a modern roundabout is to reduce to near zero the probability of a fatal crash at an intersection.  High speed is not  a feature of a modern roundabout.  The definitions do matter if you're going to confuse the three primary forms of circular intersection.

[abefroman329]

I'm talking about something like this: https://www.google.com/maps/place/W+Albion+Ave+%26+N+Ashland+Ave,+Chicago,+IL+60626/@42.0016833,-87.6704428,3a,75y,341.27h,73.45t/data=!3m7!1e1!3m5!1sD3z9-EFxlzGZMUA7Ehu6mA!2e0!6s%2F%2Fgeo2.ggpht.com%2Fcbk%3Fpanoid%3DD3z9-EFxlzGZMUA7Ehu6mA%26output%3Dthumbnail%26cb_client%3Dsearch.TACTILE.gps%26thumb%3D2%26w%3D86%26h%3D86%26yaw%3D358.1608%26pitch%3D0%26thumbfov%3D100!7i13312!8i6656!4m5!3m4!1s0x880fd1bba7352b9b:0x71cc4af7019040dd!8m2!3d42.0017289!4d-87.6705046

I treat that as a roundabout and think it's reasonable to do so.  The main problem with turning left in front of the little island is that there isn't sufficient space for two-way traffic.

Meh...  I wouldn't fault anyone for turning in front of the island there.  It's just an all-way stop with a big impediment in the middle.  If I were driving, I would turn in front of it if doing so wouldn't impede any other traffic, but I'd probably treat it as a roundabout if any other cars were nearby.

It's now officially signed as a roundabout, so...I was right all along.

[MNHighwayMan]

They're all crash-prone.

Modern roundabouts are the safest form of intersection in the world - the intersection type with the lowest risk of fatal or serious injury crashes - (much more so than comparable signals).  Modern roundabouts require a change in speed and alter the geometry of one of the most dangerous parts of the system - intersections. 

The reduction in speed to about 20 mph and sideswipe geometry mean that, when a crash does happen at a modern roundabout, you usually need a tow truck, not an ambulance.  Visit the Insurance Institute for Highway Safety for modern roundabout FAQs and safety facts.  Roundabouts are one of several proven road safety features (FHWA). 
The life saved may be your own.
https://safety.fhwa.dot.gov/provencountermeasures/roundabouts/
https://safety.fhwa.dot.gov/intersection/innovative/roundabouts/

Oh man, you have no idea.

[kphoger]

They're all crash-prone.

Modern roundabouts are the safest form of intersection in the world - the intersection type with the lowest risk of fatal or serious injury crashes - (much more so than comparable signals).  Modern roundabouts require a change in speed and alter the geometry of one of the most dangerous parts of the system - intersections. 

The reduction in speed to about 20 mph and sideswipe geometry mean that, when a crash does happen at a modern roundabout, you usually need a tow truck, not an ambulance.  Visit the Insurance Institute for Highway Safety for modern roundabout FAQs and safety facts.  Roundabouts are one of several proven road safety features (FHWA). 
The life saved may be your own.
https://safety.fhwa.dot.gov/provencountermeasures/roundabouts/
https://safety.fhwa.dot.gov/intersection/innovative/roundabouts/

You're new here, and I was being sarcastic.  Please do take a look at the thread MNHighwwayMan linked to.  Do so when you have a good hour or two to read through a lot of the thread.  tradephoric, through all the noise of his rhetoric, does put forward good evidence that there is a great deal of variance in safety between simple single-lane roundabouts and larger multi-lane roundabouts.  State DOTs are only recently beginning, it seems, to get an inkling of this variance.

[jakeroot]

Guys, he's already posted in that thread on several occasions. He seems to have FritzOwl levels of defiance, repeating the same rhetoric over, and over, and over again (using very nearly the same wording too). Note this post by him in that thread from last October. The data is before him, but judging by his username including "RAB", he's probably already made up his mind what he thinks.

[kalvado]

Guys, he's already posted in that thread on several occasions. He seems to have FritzOwl levels of defiance, repeating the same rhetoric over, and over, and over again (using very nearly the same wording too). Note this post by him in that thread from last October. The data is before him, but judging by his username including "RAB", he's probably already made up his mind what he thinks.

What is RAB?

[jakeroot]

Guys, he's already posted in that thread on several occasions. He seems to have FritzOwl levels of defiance, repeating the same rhetoric over, and over, and over again (using very nearly the same wording too). Note this post by him in that thread from last October. The data is before him, but judging by his username including "RAB", he's probably already made up his mind what he thinks.

What is RAB?

RoundABout

[skluth]

I guess this would kinda count as a freeway roundabout?

https://www.google.com/maps/@46.0974443,-64.7697549,15.72z

That's a pretty big roundabout. Using the scale on Google Maps it looks like it has a diameter of roughly 1000 ft. It looks as big as the shopping mall right next to it. I wouldn't want to build such a big roundabout in the middle of any city.

It's in a flood plain. Those wetlands probably help reduce flooding nearby, even though there's practically no elevation difference between the wetlands and the mall.

[tradephoric]

ScottRAB, here's a roundabout video the IIHS put together talking about the safety of roundabouts.  You should link to this video when you are out shilling...

[MantyMadTown]

ScottRAB, here's a roundabout video the IIHS put together talking about the safety of roundabouts.  You should link to this video when you are out shilling...

Man, these people don't know how to use roundabouts. Jumping over them and trying to pass through at high speeds, that's like the most blatantly wrong thing you can do at a roundabout. They're pretty safe if you use them correctly.