Crash prone 'modern roundabouts'

[tradephoric]

Are all of your 1300 posts in this thread? It is theoretically possible, since there are 1600 replies 

Though multi-lane roundabouts can be annoying due to driver ignorance and hesitation, I fail to see how they are, functionally, any different from a standard one-lane roundabout.

Some people here are fascinated with control cities and sign shields.  Those threads aren't for me but i don't go out of my way to post on them saying i wish they would stop talking about those things.  It doesn't matter to me.  Yet i post some roundabout crash results and some people seem to get extremely defensive. 

In general, multi-lane roundabouts have higher crash rates than single-lane roundabouts.  There are a lot of explanations as to why this is the case, but quite simply there are more ways for drivers to screw up at multi-lane roundabouts (especially multi-lane roundabouts with 2x2 geometries).  I am also concerned about single-lane roundabouts that have fixed objects in the central island.  My belief is that roundabouts (whether single or double lane) should be designed with the assumption that drivers will blow through the middle of it.   This is an especially important consideration at suburban and/or rural roundabouts where link speeds are generally higher.

[webny99]

I fail to see how they are, functionally, any different from a standard one-lane roundabout.

I suspect you will learn, here, within the next day.

Smart thing to suspect. In fact, that's part of the reason I made that statement 

Though multi-lane roundabouts can be annoying due to driver ignorance and hesitation

Age: 18

I hate to ask, but how long do you have your license, Mr. Experienced Driver?

15 months, to be exact. I'm not calling myself experienced by any stretch of the imagination; however it is possible to by annoyed (and rightly so) when you are not the driver yourself. This roundabout in particular I travel through frequently and find myself annoyed with traffic flow on the approach, even from the backseat.

I should also add that despite my inexperience, I am a roadgeek, after all, and just may know more about roundabouts than some supposedly more seasoned drivers (though still less so than others here).

[kphoger]

Though multi-lane roundabouts can be annoying due to driver ignorance and hesitation, I fail to see how they are, functionally, any different from a standard one-lane roundabout.

I used to think that too.  However, I figured out a functional difference several months ago.  All of a single-lane roundabout's conflict points are side-swipe, the result of merging into a lane where there's already a car.  However, in a multi-lane roundabout, straight-through traffic can actually conflict in a more catastrophic way.

In order to avoid the green star conflict point illustrated below, the right lane of the approaches would need to be right-turn-only–effectively making it a single-lane roundabout with slip lanes.

[kalvado]

Though multi-lane roundabouts can be annoying due to driver ignorance and hesitation, I fail to see how they are, functionally, any different from a standard one-lane roundabout.

I used to think that too.  However, I figured out a functional difference several months ago.  All of a single-lane roundabout's conflict points are side-swipe, the result of merging into a lane where there's already a car.  However, in a multi-lane roundabout, straight-through traffic can actually conflict in a more catastrophic way.

In order to avoid the green star conflict point illustrated below, the right lane of the approaches would need to be right-turn-only–effectively making it a single-lane roundabout with slip lanes.

This is still a low-angle conflict, not exactly sidesweep - but closer to sidesweep than to right angle or head-on.
Bigger problem here is that driver of "blue" car has potential conflict with cars on multipe different trajectories - both lanes on the left (but maybe lower lane turns right), and car  continuing on the circle. While still making sure conflicting traffic from the right actually yields, and there is no pedestrian or bicycle.
Hazard wise, this is a RTOR into the third lane on the regular intersection. .

[kalvado]

Though multi-lane roundabouts can be annoying due to driver ignorance and hesitation

Age: 18

I hate to ask, but how long do you have your license, Mr. Experienced Driver?

15 months, to be exact. I'm not calling myself experienced by any stretch of the imagination; however it is possible to by annoyed (and rightly so) when you are not the driver yourself. This roundabout in particular I travel through frequently and find myself annoyed with traffic flow on the approach, even from the backseat.

I should also add that despite my inexperience, I am a roadgeek, after all, and just may know more about roundabouts than some supposedly more seasoned drivers (though still less so than others here).

Did it ever occur to you that if specific structure causes more problems than others, it may be problem of the structure?
I understand it is easy to blame others while considering yourself a much better driver - especially from the backseat. But, as some wise guy told me when I was learning to drive: "always remember that you're not the only idiot on this road"

[jeffandnicole]

Though multi-lane roundabouts can be annoying due to driver ignorance and hesitation

Age: 18

I hate to ask, but how long do you have your license, Mr. Experienced Driver?

15 months, to be exact. I'm not calling myself experienced by any stretch of the imagination; however it is possible to by annoyed (and rightly so) when you are not the driver yourself. This roundabout in particular I travel through frequently and find myself annoyed with traffic flow on the approach, even from the backseat.

I should also add that despite my inexperience, I am a roadgeek, after all, and just may know more about roundabouts than some supposedly more seasoned drivers (though still less so than others here).

Did it ever occur to you that if specific structure causes more problems than others, it may be problem of the structure?
I understand it is easy to blame others while considering yourself a much better driver - especially from the backseat. But, as some wise guy told me when I was learning to drive: "always remember that you're not the only idiot on this road"

Well, while Trade tends to be very specific in the roundabouts he identifies as being problematic, you tend to treat them all as bad guys.  If one has a problem, they al don't necessarily have a problem.

And web's age shouldn't have anything to do with it, because it's not just 18 year olds getting into accidents in roundabouts. If someone gets their license at 40, they may be a little more mature *in general* than 18 year olds, but they aren't any more experienced driving than an 18 year old.

[kalvado]

Well, while Trade tends to be very specific in the roundabouts he identifies as being problematic, you tend to treat them all as bad guys.  If one has a problem, they al don't necessarily have a problem.

And web's age shouldn't have anything to do with it, because it's not just 18 year olds getting into accidents in roundabouts. If someone gets their license at 40, they may be a little more mature *in general* than 18 year olds, but they aren't any more experienced driving than an 18 year old.

I tend to believe that roundabouts are sort of "cargo cult" as it stands. Some may work, but that seems a minority from my experience. Even fewer of them are actually better that other possible arrangements.

As for age - there are statistical reasons why Web's insurance premium should be 3x higher than mine. It is entirely possible that Web himself is a Nascar-grade driver with exceptional abilities.. But he talks as a literally backseat driver criticizing those who are actually behind the wheel.
Which is perfectly normal for 18 year old  - I think I was even bigger pain in the rear at that age. And I wouldn't even bother if that was something benign - but such approach can easily translate into cavalier attitude on the road. Hence my usual "idiot" comment.  And yes, I do remember that I am probably an average driver surrounded by average drivers - and we all prone to mistakes.

[kphoger]

I tend to believe that roundabouts are sort of "cargo cult" as it stands. Some may work, but that seems a minority from my experience.

I know we kind of had this discussion earlier, but what do you mean by "work"?  What roundabouts in your experience don't work and why?

[jakeroot]

Kalvado hates all roundabouts.

You're cutting a corner here.
Kalvado hates, when things are done just for sake of doing it "cool" without understanding. Most roundabouts I saw are built because they are cool, without underlying understanding. Hence...

So, you hate the engineers? The roundabouts didn't build themselves...

Roundabouts are not built because they're "cool". They're built because the engineers think they'll improve things.

[kalvado]

Kalvado hates all roundabouts.

You're cutting a corner here.
Kalvado hates, when things are done just for sake of doing it "cool" without understanding. Most roundabouts I saw are built because they are cool, without underlying understanding. Hence...

So, you hate the engineers? The roundabouts didn't build themselves...

Roundabouts are not built because they're "cool". They're built because the engineers think they'll improve things.

Looks like a lot of folks are hired to build roads, not to think about it...

[jakeroot]

Kalvado hates all roundabouts.

You're cutting a corner here.
Kalvado hates, when things are done just for sake of doing it "cool" without understanding. Most roundabouts I saw are built because they are cool, without underlying understanding. Hence...

So, you hate the engineers? The roundabouts didn't build themselves...

Roundabouts are not built because they're "cool". They're built because the engineers think they'll improve things.

Looks like a lot of folks are hired to build roads, not to think about it...

As I've mentioned up-thread several times, not all engineers are privy to data we might think they are. There are conferences from time to time, but not all engineers attend them.

Here's a new way of looking at things: consider all the cities, towns, and counties across the US that have zero roundabouts. Are the engineers who run them on top of the recent data, and have decided not to build any roundabouts? Have they thought about building them, but don't have the money? Are they even familiar with roundabouts?

[kalvado]

Kalvado hates all roundabouts.

You're cutting a corner here.
Kalvado hates, when things are done just for sake of doing it "cool" without understanding. Most roundabouts I saw are built because they are cool, without underlying understanding. Hence...

So, you hate the engineers? The roundabouts didn't build themselves...

Roundabouts are not built because they're "cool". They're built because the engineers think they'll improve things.

Looks like a lot of folks are hired to build roads, not to think about it...

As I've mentioned up-thread several times, not all engineers are privy to data we might think they are. There are conferences from time to time, but not all engineers attend them.

Here's a new way of looking at things: consider all the cities, towns, and counties across the US that have zero roundabouts. Are the engineers who run them on top of the recent data, and have decided not to build any roundabouts? Have they thought about building them, but don't have the money? Are they even familiar with roundabouts?

Yes of course, that is a part of it.
However back in 5000 BC people invented a cool thing called "writing". That allows a person - "reader" - to get a message from a "writer" far away, and possibly years later.. Over time, that was perfected into "books", "magazines", "guidelines", "laws", "manuals", "journals" - and many other forms. There is plenty of data going around.
However some things lost over time are "common sense" and "critical thinking" - sometimes not replaces by proper "reading" skills, as you mentioned. And that creates some interesting situations as you described.

But overall I can see significant number of design flaws around. For example - I can think of at least 4 issues on local divided highways where stripping is apparently flawed- but is not fixed for many years. I am not talking about expensive projects where funding may be an issue, but about simple lines on a pavement.
So I have to remind myself, as I did above - most professionals around are about average, and half of them are worse than average. And person with lowest passing grade in medical school is still called a "doctor". But I don't have to be happy about overall outcome.

[kphoger]

For example - I can think of at least 4 issues on local divided highways where stripping is apparently flawed- but is not fixed for many years. I am not talking about expensive projects where funding may be an issue, but about simple lines on a pavement.

If it's a minor error, then it's easy for me to imagine it being far down the list of projects.  Basically in the "if money flies through the window" category.

[kalvado]

For example - I can think of at least 4 issues on local divided highways where stripping is apparently flawed- but is not fixed for many years. I am not talking about expensive projects where funding may be an issue, but about simple lines on a pavement.

If it's a minor error, then it's easy for me to imagine it being far down the list of projects.  Basically in the "if money flies through the window" category.

Is daily traffic jam because of that stripping is a good enough reason to move things up the list?
Somehow roundabouts do get funding - including funding under "reducing air pollution" category...
Or, even better, a full rebuild of a road exactly according decades old blueprints - without taking into account new traffic distribution, but carefully replicating decades old flaw which caused 2 fatal accident just over past 2 years? 

[webny99]

Did it ever occur to you that if specific structure causes more problems than others, it may be problem of the structure?

Of course, but I fail to see the relevance of that question.

[kalvado]

Did it ever occur to you that if specific structure causes more problems than others, it may be problem of the structure?

Of course, but I fail to see the relevance of that question.

Because you squarely attributed the problem to

driver ignorance and hesitation

Looking at the "age" field, I suspect that your driving experience is not sufficient to realize that roads are less than perfect, that another explanation to "hesitation" is envisioning hazard you are not seeing and so on. Hence my question.
More than a year seem to be sufficient experience to recognize those things - of course if you were actively driving during that time.

[jeffandnicole]

Did it ever occur to you that if specific structure causes more problems than others, it may be problem of the structure?

Of course, but I fail to see the relevance of that question.

Agreed. He seems way overfocused on your age. No clue what "structures" he's referring to. And unless it's a bunch of 18 year olds having accidents on those structures, age doesn't matter.

[kalvado]

Did it ever occur to you that if specific structure causes more problems than others, it may be problem of the structure?

Of course, but I fail to see the relevance of that question.

Agreed. He seems way overfocused on your age. No clue what "structures" he's referring to. And unless it's a bunch of 18 year olds having accidents on those structures, age doesn't matter.

[jakeroot]

Looking at the "age" field, I suspect that your driving experience is not sufficient to realize that roads are less than perfect, that another explanation to "hesitation" is envisioning hazard you are not seeing and so on. Hence my question.
More than a year seem to be sufficient experience to recognize those things - of course if you were actively driving during that time.

Wait...so he's not experienced enough to realise that experience isn't necessarily important?

[webny99]

Did it ever occur to you that if specific structure causes more problems than others, it may be problem of the structure?

Of course, but I fail to see the relevance of that question.

Because you squarely attributed the problem to

driver ignorance and hesitation

I meant drivers are hesitant and ignorant when using roundabouts, and especially new ones. It doesn't mean there's a problem with the roundabout, it's just a fact of life that change takes some getting used to, especially on the road. Roundabouts are, after all, a relatively new concept.

Looking at the "age" field, I suspect that your driving experience is not sufficient to realize that roads are less than perfect,

You really went there?  I've been dreaming up road improvements longer than I can remember. I'm the first to notice glitches or imperfections

that another explanation to "hesitation" is envisioning hazard you are not seeing and so on. Hence my question.

Hesitation comes from lack of experience making a movement, or uncertainty as to what to expect from other drivers. It mellows with time.

More than a year seem to be sufficient experience to recognize those things - of course if you were actively driving during that time.

I actively drive every day, and go out of my way to drive extra miles, too.

Agreed. He seems way overfocused on your age. No clue what "structures" he's referring to. And unless it's a bunch of 18 year olds having accidents on those structures, age doesn't matter.

Agreed. With age comes experience, so of course learners are slightly more of a risk on the road. But:
1] I'm no longer a learner.
2] in the case of a roadgeek, knowledge comes many years before experience.
3] My age has no bearing on this particular knowledge-based discussion whatsoever.

(Oh, and I assumed "structures" = roundabouts  )

[kphoger]

I can think of at least 4 issues on local divided highways where stripping is apparently flawed- but is not fixed for many years ... simple lines on a pavement.

If it's a minor error, then it's easy for me to imagine it being far down the list of projects.  Basically in the "if money flies through the window" category.

Is daily traffic jam because of that stripping is a good enough reason to move things up the list?

Where the heck are these four places where "simple lines on a pavement" are causing "daily traffic jam"?  Have you brought them up with the appropriate agency?

[jakeroot]

https://youtu.be/UWqzmVGKDNk

[Hurricane Rex]

Kalvado hates all roundabouts.

You're cutting a corner here.
Kalvado hates when things are done just for sake of doing it "cool" without understanding. Most roundabouts I saw are built because they are cool, without underlying understanding. Hence...

So, you hate the engineers? The roundabouts didn't build themselves...

Roundabouts are not built because they're "cool". They're built because the engineers think they'll improve things.

Looks like a lot of folks are hired to build roads, not to think about it...

Trying to be humorous and serious but may fail miserably: And if they don't what then?

[tradephoric]

https://youtu.be/UWqzmVGKDNk

I knew that Washington compact roundabout design looked familiar to me.  This fatal crash happened at the Badger Rd & Northwood Rd roundabout near Lynden less than a year after the roundabout was completed. 



http://www.bellinghamherald.com/news/local/article153269789.html

[jakeroot]

https://youtu.be/UWqzmVGKDNk

I knew that Washington compact roundabout design looked familiar to me.  This fatal crash happened at the Badger Rd & Northwood Rd roundabout near Lynden less than a year after the roundabout was completed. 

http://www.bellinghamherald.com/news/local/article153269789.html

I don't know why they opted for a mini rounbabout at Northwood, when the preceding roundabouts at Bender and Depot were full-scale roundabouts. Nonetheless, the crash pictured was a classic T-bone possible at all roundabouts.

From the perspective of someone who passes by the Slater Rd roundabouts on a decently frequent basis, the roundabouts do seem to have been a smart choice for the ramp terminals, even if those terrible side-impact crashes are still a possibility.

IIRC, you don't really have a problem with single-lane roundabouts, right?