Crash prone 'modern roundabouts'

[kphoger]

That's exactly why I don't think roundabouts are a bad idea, but I just think DOTs - or their equivalents - should not be allowed to build those until they have at least 50 years of experience in building roundabouts.

What is exactly why you think they shouldn't?  Everything he posted makes total sense to me, and it's the way I think roundabouts should be designed and function.  Whenever I've driven a roundabout that was striped like that (such as this one or this one), it was intuitive to use.

[kalvado]

That's exactly why I don't think roundabouts are a bad idea, but I just think DOTs - or their equivalents - should not be allowed to build those until they have at least 50 years of experience in building roundabouts.

What is exactly why you think they shouldn't?  Everything he posted makes total sense to me, and it's the way I think roundabouts should be designed and function.  Whenever I've driven a roundabout that was striped like that (such as this one or this one), it was intuitive to use.

It's more global. There is no institutional understanding of what is being built.
There are old style traffic circles with one set of rules, there are "modern" turbo  roundabouts with another set of rules.
We are talking about some random mixture of concepts being built, with serious problems due to squeezing them into minimal possible footprint (as they happen in already built-up areas), with serious problems for nonhcar traffic (both big vehicles and pedestrians) and no trend for improvement.
I can buy a "learning curve" explanation - but after 20 years it's not a learning curve, it should become a dropout.

[Rothman]

That's exactly why I don't think roundabouts are a bad idea, but I just think DOTs - or their equivalents - should not be allowed to build those until they have at least 50 years of experience in building roundabouts.

What is exactly why you think they shouldn't?  Everything he posted makes total sense to me, and it's the way I think roundabouts should be designed and function.  Whenever I've driven a roundabout that was striped like that (such as this one or this one), it was intuitive to use.

It's more global. There is no institutional understanding of what is being built.
There are old style traffic circles with one set of rules, there are "modern" turbo  roundabouts with another set of rules.
We are talking about some random mixture of concepts being built, with serious problems due to squeezing them into minimal possible footprint (as they happen in already built-up areas), with serious problems for nonhcar traffic (both big vehicles and pedestrians) and no trend for improvement.
I can buy a "learning curve" explanation - but after 20 years it's not a learning curve, it should become a dropout.

I find this an uninformed extreme position given my own experience and even despite some problematic implementations of roundabouts.  The idea that there is no state of the art ("institutuonal understanding") regarding roundabout design is absolutely ridiculous as there are indeed standards and expertise that are brought to bear for such.  We're at the point where, at least in NY, the vast majority of roundabout projects are not problematic.

It's not like mistakes aren't made here and there in transportation projects across the board, anyway.  Society will continue to fix such as if warranted.

[kphoger]

It's more global. There is no institutional understanding of what is being built.
There are old style traffic circles with one set of rules, there are "modern" turbo  roundabouts with another set of rules.
We are talking about some random mixture of concepts being built, with serious problems due to squeezing them into minimal possible footprint (as they happen in already built-up areas), with serious problems for nonhcar traffic (both big vehicles and pedestrians) and no trend for improvement.
I can buy a "learning curve" explanation - but after 20 years it's not a learning curve, it should become a dropout.

But you responded to a post highlighting how uniform the expectations are between Alberta and Ontario as to lane usage—and which others have already pointed out is the expectation in other places as well.  This sounds to me like more of a global understanding than you're giving it credit for.  The only examples I've seen on here—from you—of where it's OK to switch lanes between entering and exiting a roundabout have been where it's clearly striped to allow it, to the point that it barely counts as changing lanes at all.

[kalvado]

That's exactly why I don't think roundabouts are a bad idea, but I just think DOTs - or their equivalents - should not be allowed to build those until they have at least 50 years of experience in building roundabouts.

What is exactly why you think they shouldn't?  Everything he posted makes total sense to me, and it's the way I think roundabouts should be designed and function.  Whenever I've driven a roundabout that was striped like that (such as this one or this one), it was intuitive to use.

It's more global. There is no institutional understanding of what is being built.
There are old style traffic circles with one set of rules, there are "modern" turbo  roundabouts with another set of rules.
We are talking about some random mixture of concepts being built, with serious problems due to squeezing them into minimal possible footprint (as they happen in already built-up areas), with serious problems for nonhcar traffic (both big vehicles and pedestrians) and no trend for improvement.
I can buy a "learning curve" explanation - but after 20 years it's not a learning curve, it should become a dropout.

I find this an uninformed extreme position given my own experience and even despite some problematic implementations of roundabouts.  The idea that there is no state of the art ("institutuonal understanding") regarding roundabout design is absolutely ridiculous as there are indeed standards and expertise that are brought to bear for such.  We're at the point where, at least in NY, the vast majority of roundabout projects are not problematic.

It's not like mistakes aren't made here and there in transportation projects across the board, anyway.  Society will continue to fix such as if warranted.

Well, you probably know that I live in Malta NY, a wanna-be Carmel Jr.  And I am not enchanted with NYSDOT design quality in general, nor roundabouts in particular. 
Let's focus on roundabout design for now. Just remember that NYSDOT designed roundabouts made the top of the list of most crash prone ones in Albany area. Yes, less fatal - but still, millions invested for making one to go on top of crash list?
More specific examples:
 Do you think that NYSDOT ones on Rt.9 in Malta are turbo or not? What does NYS V&T have to say about lane change within the circle - turbo style or circle style? Although it is "barely counts" as @kphoger says, it is certainly something road designer has to know with absolute certainty, and implement so that movements fully conform to traffic laws...

[tradephoric]

Studies have shown that roundabouts reduce fatal crashes by 90% compared to traditional intersections.  There are roughly 330k traffic signals in America and 10k roundabouts.  What is the probability that the deadliest intersection in America would be at a roundabout?  How would you solve this?

[kphoger]

Well, that didn't take long to find...

[kphoger]

What does NYS V&T have to say about lane change within the circle - turbo style or circle style?

To answer this specific question:  while New York state traffic law defines a roundabout as an intersection, it appears that changing lanes within an intersection is not prohibited there.

[tradephoric]

Things are getting real when Jason Momoa is directing traffic following another roundabout crash at this notorious Milwaukee roundabout:

Viral video shows van almost hit two pedestrians in Milwaukee roundabout
Bystanders rushed to help the driver, including Jason Momoa, who was in town for the Harley-Davidson Homecoming
https://www.wisn.com/article/milwaukee-roundabout-near-crash-reckless-driving/65402503

[tradephoric]

According to Jeremy Carter, the Traffic and Development Engineer for the city of Rockford, there was a 60% reduction in crashes at the Auburn @ Main roundabout when it was converted from a 2x2 to a 1x1 roundabout.  I'm surprised they didn't keep 2 lanes along Auburn Street, as 2x1 roundabouts can function pretty well while minimizing crashes.  Now that it's a single lane roundabout there are complaints of excess delays in the area.

Rockford officials report 60% decrease in crashes at Auburn St. roundabout
https://www.wifr.com/2025/07/14/rockford-officials-report-60-decrease-crashes-auburn-st-roundabout/

[kphoger]

I realize this is tangential to the topic...

The other day, I was watching traffic at this intersection in KCMO, which has a mini-roundabout island in the middle.  Traffic on 38th has stop signs, and traffic on Roanoke has nothing.  Two observations:

1.  More than once, I saw a drier on 38th decide to go through the intersection just as a vehicle was approaching on Roanoke.  My assumption is that, at typical modern roundabouts, all approaches have yield signs, so perhaps the driver on 38th assumed the driver on Roanoke had some sort of yield sign or stop sign.  Fortunately, because of the low speeds involved, I didn't witness any truly close calls.  And, surprisingly, I never heard anyone honk their horn.

2.  Probably one out of every four left-turning drivers I saw decided to cut the corner instead of going around the island.  Since the GSV car last went through, signs were installed on the central island instructing drivers to keep right, but those signs were ignored by a sizeable number of the drivers I watched.  It didn't seem to matter, though, as I never saw it happen when there was cross-traffic present.

[Scott5114]

I wonder if that was intended to be a "mini-roundabout" when it was built. It's present in 2007 imagery and looked old even then. It could be that the drivers are treating it the same way as they have for decades despite the city trying to retrofit roundabout rules onto it.

More than once, I saw a drier on 38th decide to go through the intersection . . .

A lot of appliance deliveries in that neighborhood, huh?

[kphoger]

More than once, I saw a drier on 38th decide to go through the intersection . . .

A lot of appliance deliveries in that neighborhood, huh?

I used to drive a delivery truck in the southern Illinois area.  Every so often, I'd have to cover the route that went up to the Saint Louis area, and occasionally I'd have to go over to the St Charles area to pick up a laundry machine or two.  (The company sold janitorial supplies, but the owner was brothers with the owner of a hardware store in a nearby town, and that's actually where we picked our paychecks up from.)  One time, a different driver picked up a washer or a dryer, got back to the Illinois side to make one of his usual deliveries, realized that the roll-up door was rolled up, and also realized that the appliance was no longer on the truck.  We assumed it must have bounced its way out onto the Interstate somewhere in metro Saint Louis.

[tradephoric]

Quite possibly the most dangerous roundabout in the world, a group of unknown people demolished the Coptic roundabout in Kenya just a week after a crash claimed the lives of 26 people when a bus overturned at the roundabout. This wasn't the first mass casualty event that has occurred at this roundabout (this article was from last year):

Killer Kisumu roundabout that has claimed many lives
https://nation.africa/kenya/counties/kisumu/killer-kisumu-roundabout-that-has-claimed-many-lives--4700252#story

Why is the roundabout so dangerous?  The slope approaching the roundabout is roughly 7% along a high speed arterial street with a slight curve in the road as you are approaching the roundabout.  Perhaps the only thing that could have made this roundabout more deadly is if they had lined the central island with jagged rocks to ensure that the gas and oil lines will be severed if an out of control driver runs over the central island (like the Silver Springs, Nevada roundabout which itself is a notoriously deadly roundabout in America.. it too has a large grade approaching the roundabout).  Just a recipe for disaster.

https://www.google.com/maps?ll=-0.05676,34.77509&z=19&t=h

[tradephoric]

A central island that resembles this could have made that Kenyan roundabout just a little bit more dangerous.  If you want to take the crown for designing the deadliest roundabout in the world, go all the way with it.