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[Plutonic Panda]

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.

Let's please not make this a thing. Completely defeats the purpose of a "freeway"!

[tradephoric]

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. 

A 2017 roundabout study out of Minnesota found that the dual lane roundabouts saw a 6% increase in injury crashes and a 212.5% increase in PDO crashes.   If we use FHWA’s comprehensive crash costs by injury severity level to perform a cost/benefit analysis, we see that these dual-lane Minnesota roundabouts increased crash costs by $1,664,300 over the comparable intersections they replaced.  Even though there were 3 less A-level crashes at the roundabouts, there were 7 more C-level crashes and a whopping 270 more PDO crashes.


http://www.dot.state.mn.us/trafficeng/safety/docs/roundaboutstudy.pdf

BEFORE ROUNDABOUT CRASH COSTS = $4,882,600
Fatality (K)           0 X $4,008,900 = $0
Disabling Injury (A)   3 X  $216,000 = $648,000
Evident Injury (B)   15 X $79,000 = $1,185,000
Possible Injury (C)   46 X $44,900 = $2,065,400
PDO (O)          133 X $7,400 =  $984,200

AFTER ROUNDABOUT CRASH COSTS = $6,546,900
Fatality (K)           0 X $4,008,900 = $0
Disabling Injury (A)   0 X  $216,000 = $0
Evident Injury (B)   15 X $79,000 = $1,185,000
Possible Injury (C)   53 X $44,900 = $2,379,700
PDO (O)          403 X $7,400 =  $2,982,200

Instead of constructing complex multi-lane roundabouts that are prone to crashes (and increases in injury crashes) maybe agencies should consider innovative signal designs that eliminate direct left turns.  Median U-turns have been implemented in Michigan for over 50 years and have proven safety benefits with the FHWA estimating that they reduce injury crashes by 30% https://safety.fhwa.dot.gov/intersection/alter_design/pdf/fhwasa14069_mut_infoguide.pdf.  A 30% decrease in injury crashes sounds pretty good compared to a 6% increase in injuries these complex roundabouts are seeing.

[1]

Sometimes, it's hard to tell a roundabout/rotary/traffic circle from a median U-turn. See US 1 at I-95 in Danvers, MA.

[tradephoric]

Sometimes, it's hard to tell a roundabout/rotary/traffic circle from a median U-turn. See US 1 at I-95 in Danvers, MA.

That interchange really does start to mirror a median U-turn.  Here's a synchro model that is very similar to that US 1 at I-95 interchange just the off-ramp are signalized instead of free-flowing.  I like the concept.

[kalvado]

Sometimes, it's hard to tell a roundabout/rotary/traffic circle from a median U-turn. See US 1 at I-95 in Danvers, MA.

Topological similarity, maybe, but not conceptual similarity, I would say. Need to change lanes, much larger scale compared to a typical roundabout.
But overall, there are often examples where extreme cases are clearly different, but there are some intermediates which are neither one nor the other.  My pet example for today is viruses, which are neither alive nor truly dead - but somewhere in between, achoo....

[NE2]

freeway roundabout

[kphoger]

You keep viruses as pets?

[kphoger]

freeway roundabout

mmmm,,,   .......   barely.... ?

[kalvado]

You keep viruses as pets?

Hopefully just for a few days at most.

[NE2]

More freeway roundabouts:
Fredericton NB: https://www.google.com/maps/@45.9397918,-66.666871,3a,75y,315.88h,86.34t/data=!3m6!1e1!3m4!1sHs8rcLur-7Odtd1RF0HMsQ!2e0!7i13312!8i6656
Pictou NS: https://www.google.com/maps/@45.6858615,-62.728353,3a,29.8y,209.16h,87.95t/data=!3m6!1e1!3m4!1stTYvOlCuIIqEuykWjZYCQg!2e0!7i13312!8i6656

[skluth]

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.

This triple-lane roundabout in Wisconsin replaced a trumpet interchange about 10 years ago:

https://www.google.com/maps/@44.9210291,-91.3805333,156m/data=!3m1!1e3

I wouldn't be surprised if WIDoT is thinking about one somewhere right now.

[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)

I updated the roundabout database and changed the title to "Over 7000 roundabouts in America".  The kittelson website had a bunch of modern roundabouts that weren't included in my database.  The difference between my database and kittelson is that mine mainly focuses on modern roundabouts while they include traffic circles, rotaries, roundabouts, traffic calming circles, and mini roundabouts. I even stumbled upon a few culdesac circles in their database. 

Here is my database with about 7000 modern roundabouts:
http://www.mediafire.com/file/j6zcvi91whg3j2u/Roundabouts+%282019-02-12%29.kmz

[kphoger]

Fredericton NB: https://www.google.com/maps/@45.9397918,-66.666871,3a,75y,315.88h,86.34t/data=!3m6!1e1!3m4!1sHs8rcLur-7Odtd1RF0HMsQ!2e0!7i13312!8i6656

That's a great example!

This triple-lane roundabout in Wisconsin replaced a trumpet interchange about 10 years ago:

https://www.google.com/maps/@44.9210291,-91.3805333,156m/data=!3m1!1e3

I don't think it's fair to call something a "triple-lane roundabout" when...
 (a) all approach roads are two lanes,
 (b) the circulating roadway is two lanes.

There's only the briefest segment that has three lanes inside the actual roundabout.

[MNHighwayMan]

I don't think it's fair to call something a "triple-lane roundabout" when...
 (a) all approach roads are two lanes,
 (b) the circulating roadway is two lanes.

There's only the briefest segment that has three lanes inside the actual roundabout.

It's a 2¼ lane roundabout then.

[skluth]

More freeway roundabouts:
Fredericton NB: https://www.google.com/maps/@45.9397918,-66.666871,3a,75y,315.88h,86.34t/data=!3m6!1e1!3m4!1sHs8rcLur-7Odtd1RF0HMsQ!2e0!7i13312!8i6656
Pictou NS: https://www.google.com/maps/@45.6858615,-62.728353,3a,29.8y,209.16h,87.95t/data=!3m6!1e1!3m4!1stTYvOlCuIIqEuykWjZYCQg!2e0!7i13312!8i6656

I wouldn't consider the Pictou example as a freeway roundabout as it's not a freeway. NS 106 is two lanes. It may be limited access, but that doesn't make it a freeway.

[kphoger]

More freeway roundabouts:
Fredericton NB: https://www.google.com/maps/@45.9397918,-66.666871,3a,75y,315.88h,86.34t/data=!3m6!1e1!3m4!1sHs8rcLur-7Odtd1RF0HMsQ!2e0!7i13312!8i6656
Pictou NS: https://www.google.com/maps/@45.6858615,-62.728353,3a,29.8y,209.16h,87.95t/data=!3m6!1e1!3m4!1stTYvOlCuIIqEuykWjZYCQg!2e0!7i13312!8i6656

I wouldn't consider the Pictou example as a freeway roundabout as it's not a freeway. NS 106 is two lanes. It may be limited access, but that doesn't make it a freeway.

Looks like a freeway to me.  The number of lanes is rather irrelevant:  controlled access, no cross-traffic.  The only thing is that it might be short enough that the whole highway segment could be discounted as a freeway simply because the roundabout exists.

[formulanone]

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...

You posted a video posting every idiotic maneuver by inattentiveness or being flat-out dangerous, but surely it's the roundabout's fault.

You must be a traffic light sales-hole.

[Max Rockatansky]

Saw the title of the thread changed numbers, let me know when it’s over 9,000. 

[jakeroot]

You posted a video posting every idiotic maneuver by inattentiveness or being flat-out dangerous, but surely it's the roundabout's fault.

You must be a traffic light sales-hole.

He's simply highlighting the FHWA's ridiculous notion that roundabouts force drivers to do anything: slow down, yield, etc. Those things only happen if drivers choose to do them. Which most people will, yeah. But those that don't... they're gonna have a bad time.

And, before anyone says anything, none of this Darwinism business. Engineers are in the business of saving all lives, even the morons.

[vdeane]

Fredericton NB: https://www.google.com/maps/@45.9397918,-66.666871,3a,75y,315.88h,86.34t/data=!3m6!1e1!3m4!1sHs8rcLur-7Odtd1RF0HMsQ!2e0!7i13312!8i6656

That's a great example!

*cough*

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.

NY 590 also comes close at Titus Avenue, though there's an at-grade RIRO just to the south.  NB 8 in Fredericton is probably the true example.

[billpa]

You posted a video posting every idiotic maneuver by inattentiveness or being flat-out dangerous, but surely it's the roundabout's fault.

You must be a traffic light sales-hole.

He's simply highlighting the FHWA's ridiculous notion that roundabouts force drivers to do anything: slow down, yield, etc. Those things only happen if drivers choose to do them. Which most people will, yeah. But those that don't... they're gonna have a bad time.

And, before anyone says anything, none of this Darwinism business. Engineers are in the business of saving all lives, even the morons.

The problem with the old thread and now, predictably this one, are the videos and stories handpicked to attempt to put roundabouts in a bad light. If someone drives at 60 mph strait through a roundabout the design and theory behind the intersection is not at fault. No one makes an argument that plowing through a red light means traffic light-controlled intersections are inherently dangerous.

Pixel 2

[jeffandnicole]

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...

I don't see anything that shows the IIHS is responsible for this video.  Someone simply took their logo, stuck it at the front of the video, and found other clips of accidents.  Heck, how does someone passing in a non-passing zone have anything to do with the roundabout?

[english si]

He's simply highlighting the FHWA's ridiculous notion that roundabouts force drivers to do anything: slow down, yield, etc. Those things only happen if drivers choose to do them.

This is true, but the way they want DOTs to do the geometry, etc does a better and more hands-on job at getting them to obey than mere signs, or lights by making the danger clear and present - rather than unseen and only there sometimes (say if you run a red light when traffic is quiet).

'Force' isn't quite the right word, but what the FHWA is getting at is to 'strongly encourage' people do something with more than just words and potential threat (of a ticket or a smash).

Of course, the engineers don't always get it correct, and the drivers likewise are sometimes unfit to be safe on the road and will come a cropper when they don't obey the strong encouragement to follow the rules of the roundabout when they might survive running through a stop sign or red light.

[D-Dey65]

Meh.  NY 85 SB after becoming two lanes to cross the Thruway is not a freeway.

Somehow I think the use of the roundabouts might be a way to get people south of the Thruway to accept four lanes along NY 85, even if it isn't.

OT, I think I see a few makeshift exit ramp parts at some intersections in Voorheesville on GSV at places like Clipp Road and the vicinity of Helderhill Road.

[Rothman]

Meh.  NY 85 SB after becoming two lanes to cross the Thruway is not a freeway.

Somehow I think the use of the roundabouts might be a way to get people south of the Thruway to accept four lanes along NY 85, even if it isn't.

OT, I think I see a few makeshift exit ramp parts at some intersections in Voorheesville on GSV at places like Clipp Road and the vicinity of Helderhill Road.

The bypass has been a great improvement.  The light at Blessing Road was horrendous and almost seemed unnecessary; the roundabout there has been most welcome.  Getting through the lights on New Scotland was annoying and, although there were quite a number of fender benders due to human error at the get-go, I haven't seen an accident at the NY 85/NY 140 roundabout in a very long time (tradephoric likes to focus on the accident-prone transition period and ignore when accident dropoffs happen at those same sites).

So, I don't know how much the roundabouts were for convincing Bethlehem that four lanes were needed as much as it was built to address the congestion and to allow some commercial development (although I can't imagine that Shop Rite is doing very well from the traffic I see).

The Clipp Road thing is just a private pullout (you can see the property signs on the trees).  Same goes for Helderhill.