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Author Topic: Crash prone 'modern roundabouts'  (Read 313062 times)

jamess

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Re: Crash prone 'modern roundabouts'
« Reply #2450 on: February 14, 2020, 04:20:47 PM »

Damn, they would have cleared the circle without those freakin' rocks!

It was built two years ago, according to Google Earth (can't find any online documents).

Another job well done in getting a dangerous driver off the road before they could kill someone.

Better no crashes at all.

Aside from a mandatory breath analyzer in every cars, what's another solution?
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Re: Crash prone 'modern roundabouts'
« Reply #2451 on: February 14, 2020, 05:12:09 PM »

Better no crashes at all.
Aside from [clipped], what's another solution?
Even better if no one drove recklessly. They were bound to hit something or someone eventually.

So, if I get this correctly, the solution to crashes, is to cause the bad drivers to crash, learn their lesson (either by seriously injuring or killing themselves, and/or causing lots of property damage), and then...less crashes?

Seems kind of archaic. And a bit backwards, to be honest.

But there's a problem: bad drivers are born every day, they just don't hit the road for another 16 years. We need to do more to prevent bad driving to begin with, rather than ruining the life of someone whose judgement occasionally lapses. I guess this means either stricter training, more expensive licensing programs, cars that drive themselves, and importantly for us road-geeks: designing infrastructure to reduce the chance of collision.
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kalvado

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Re: Crash prone 'modern roundabouts'
« Reply #2452 on: February 14, 2020, 05:15:20 PM »

Better no crashes at all.
Aside from [clipped], what's another solution?
Even better if no one drove recklessly. They were bound to hit something or someone eventually.

So, if I get this correctly, the solution to crashes, is to cause the bad drivers to crash, learn their lesson (either by seriously injuring or killing themselves, and/or causing lots of property damage), and then...less crashes?

Seems kind of archaic. And a bit backwards, to be honest.

But there's a problem: bad drivers are born every day, they just don't hit the road for another 16 years. We need to do more to prevent bad driving to begin with, rather than ruining the life of someone whose judgement occasionally lapses. I guess this means either stricter training, more expensive licensing programs, cars that drive themselves, and importantly for us road-geeks: designing infrastructure to reduce the chance of collision.

Thinking about it... Such crashes are exact equivalent of T-bone on a traffic light. So one line less in roundabout advantages list?
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DaBigE

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Re: Crash prone 'modern roundabouts'
« Reply #2453 on: February 14, 2020, 06:58:54 PM »

Better no crashes at all.
Aside from [clipped], what's another solution?
Even better if no one drove recklessly. They were bound to hit something or someone eventually.

So, if I get this correctly, the solution to crashes, is to cause the bad drivers to crash, learn their lesson (either by seriously injuring or killing themselves, and/or causing lots of property damage), and then...less crashes?

Seems kind of archaic. And a bit backwards, to be honest.

No, you don't have it correctly, at least not based on what you selectively bolded. The context of my comment was exclusive of the (IRONY ALERT) traffic calming device. Someone going as fast as the person in the video is bound to hit something, especially when under the influence...another vehicle, tree, person taking their dog out to pee, etc. It unfortunately happens on perfectly straight roads without any obstacles such as a traffic circle (note: roundabouts DON'T have stop signs). I wasn't even beginning to imply that reckless drivers need to be taught a harsh lesson, rather it's the laws of probability: drive well in excess of the speed limit in an urban, tree and parked car-lined environment, chances are very high that the ending is not going to be good. Cut the reckless driving, and there would be a lot fewer crashes everywhere. What's shown in the video easily could have happened at a green-T intersection with similar results.
« Last Edit: February 14, 2020, 07:03:01 PM by DaBigE »
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jakeroot

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Re: Crash prone 'modern roundabouts'
« Reply #2454 on: February 14, 2020, 08:04:09 PM »

Better no crashes at all.
Aside from [clipped], what's another solution?
Even better if no one drove recklessly. They were bound to hit something or someone eventually.

So, if I get this correctly, the solution to crashes, is to cause the bad drivers to crash, learn their lesson (either by seriously injuring or killing themselves, and/or causing lots of property damage), and then...less crashes?

Seems kind of archaic. And a bit backwards, to be honest.

No, you don't have it correctly, at least not based on what you selectively bolded. The context of my comment was exclusive of the (IRONY ALERT) traffic calming device. Someone going as fast as the person in the video is bound to hit something, especially when under the influence...another vehicle, tree, person taking their dog out to pee, etc. It unfortunately happens on perfectly straight roads without any obstacles such as a traffic circle (note: roundabouts DON'T have stop signs). I wasn't even beginning to imply that reckless drivers need to be taught a harsh lesson, rather it's the laws of probability: drive well in excess of the speed limit in an urban, tree and parked car-lined environment, chances are very high that the ending is not going to be good. Cut the reckless driving, and there would be a lot fewer crashes everywhere. What's shown in the video easily could have happened at a green-T intersection with similar results.

I agree that reckless driving needs to be "cut"...are circular intersections doing that?

Here:

Chance of successfully navigating a tight urban neighborhood street at high speeds while drunk: ~25%? (it's not 0%, but even 25% implies 3/4 of drivers will crash, which is probably high)
Chance of navigating straight through a circular junction at high speeds without issue: ~0% ("about", since there are mini-roundabouts that can be driven straight over, albeit it would be exceedingly uncomfortable, and a driver could lose control)
Chance of navigating straight through a regular intersection at high speeds without issue: >0% (probably pretty good, given how many intersections they've likely cleared already)
Chance of navigating straight through a T-intersection without issue: ~0% when approaching from the stem!

You're saying that, basically, there's a ton more ways that those drivers which are reckless in their behavior could cause harm to themselves and others. My point is that circular intersections are yet another thing on that list, and I don't see how that's necessarily benefitting anyone*.

*I'm actually fine with smaller traffic-calming circles...my comment is also exclusive of the circle at 4th/Daisy in Long Beach, and speaking more to larger circular intersections in general.
« Last Edit: February 14, 2020, 10:25:52 PM by jakeroot »
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billpa

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Re: Crash prone 'modern roundabouts'
« Reply #2455 on: February 15, 2020, 08:48:41 AM »

That's not a modern roundabout. This crash belongs in another thread.

Pixel 2

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Re: Crash prone 'modern roundabouts'
« Reply #2456 on: February 15, 2020, 01:50:34 PM »

Man, every drunk driver I've had the (dis)pleasure of getting a ride from has gone way under the speed limit.  Granted, I've seen drunk drivers going over the speed limit, but I've never personally been in the car with such a driver.



That's not a modern roundabout. This crash belongs in another thread.

Great point.  Discussion over.
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DaBigE

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Re: Crash prone 'modern roundabouts'
« Reply #2457 on: February 15, 2020, 04:21:53 PM »

Man, every drunk driver I've had the (dis)pleasure of getting a ride from has gone way under the speed limit.  Granted, I've seen drunk drivers going over the speed limit, but I've never personally been in the car with such a driver.

DUI is broad and doesn't always mean alcohol. The way the driver was stated as getting out of the car makes it sound more like they were on a drug trip.
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jakeroot

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Re: Crash prone 'modern roundabouts'
« Reply #2458 on: February 17, 2020, 07:21:46 PM »

Would anyone know where to find data on the 106th St roundabout over I-69/IN-37 in Fishers?

It opened within the last couple years, and is definitely much larger than most roundabouts, as it spans across two overpasses:


https://ucindy.com/project/i-69-and-106th-street-interchange/
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kalvado

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Re: Crash prone 'modern roundabouts'
« Reply #2459 on: February 17, 2020, 07:38:22 PM »

Would anyone know where to find data on the 106th St roundabout over I-69/IN-37 in Fishers?

It opened within the last couple years, and is definitely much larger than most roundabouts, as it spans across two overpasses:

https://ucindy.com/project/i-69-and-106th-street-interchange/
I have no idea where the data can be, but have to say thet flying through the center of this one could have really interesting consequencies!
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jakeroot

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Re: Crash prone 'modern roundabouts'
« Reply #2460 on: February 18, 2020, 03:59:16 AM »

Would anyone know where to find data on the 106th St roundabout over I-69/IN-37 in Fishers?

It opened within the last couple years, and is definitely much larger than most roundabouts, as it spans across two overpasses:

https://ucindy.com/project/i-69-and-106th-street-interchange/
I have no idea where the data can be, but have to say thet flying through the center of this one could have really interesting consequencies!

Yeah, that's a good observation. With any luck, errant vehicles will come to a gentle stop after they slam into the jersey barrier. This is definitely one roundabout where a raised hill of vegetation is inadvisable, les you want cars flying over the freeway!
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cjw2001

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Re: Crash prone 'modern roundabouts'
« Reply #2461 on: February 24, 2020, 09:24:47 PM »


State web site for the project:  https://www.in.gov/indot/3399.htm

Youtube video:
« Last Edit: February 24, 2020, 09:29:15 PM by cjw2001 »
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skluth

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Re: Crash prone 'modern roundabouts'
« Reply #2462 on: March 14, 2020, 12:16:28 PM »

I rather like this roundabout which combines a DDI with a large, easy-to-navigate being built in my former home state of Missouri. I heard about it from MODOT's newsletter, but couldn't find more info on their website (which is not an easy site to find anything).



If you'd like to subscribe to their newsletter.
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jakeroot

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Re: Crash prone 'modern roundabouts'
« Reply #2463 on: March 14, 2020, 06:54:35 PM »

I rather like this roundabout which combines a DDI with a large, easy-to-navigate being built in my former home state of Missouri. I heard about it from MODOT's newsletter, but couldn't find more info on their website (which is not an easy site to find anything).

ttps://benefits.transportation.org/wp-content/uploads/2020/02/kansas-city-divergabout-buti-small-1-.jpg

If you'd like to subscribe to their newsletter.

All things considered, this seems like a great interchange. Single-lane roundabouts have a pretty decent record in terms of crashes, injuries, and fatalities, and DDIs have been found to be pretty effective too. If hardly anyone is exiting or entering the freeway, probably still not ideal because of the crossover. Still pretty slick.

I also see that another double-lane example was built in Lee's Summit.
« Last Edit: March 14, 2020, 06:59:38 PM by jakeroot »
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cpzilliacus

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Re: Crash prone 'modern roundabouts'
« Reply #2464 on: March 15, 2020, 11:46:26 AM »

[WSJ.com has a paywall.  If you are blocked by the paywall, leave me a PM with your e-mail address and I will send you a copy of this article.]

Wall Street Journal: Car-Crash Mystery: Why Can’t Drivers Figure Out Roundabouts?

Quote
City planners and engineers are stumped over why so many drivers can’t handle something as simple as a roundabout.

Quote
Roundabouts have proliferated around the U.S. in recent years, arriving in some areas of the Midwest and West for the first time. Yet even years after some are installed, driver confusion persists. And with confusion comes fender-benders.

Quote
Authorities have boosted public education, tweaked signs and modified roadway designs in search of solutions. The federal government is leading a study on drivers’ failure to yield to traffic when entering two-lane roundabouts, a major cause of collisions. State transportation departments from Washington to New York are helping fund the research.
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Occidental Tourist

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Re: Crash prone 'modern roundabouts'
« Reply #2465 on: April 13, 2020, 05:55:03 PM »

The Los Alamitos (Long Beach, CA) Traffic Circle, which was a free flowing rotary with a three entry lanes and a couple of dedicated rights, has been changed to a roundabout with two entry lanes and lane controls.

I'll try to get you some pics when I get a chance.
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tradephoric

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Re: Crash prone 'modern roundabouts'
« Reply #2466 on: April 15, 2020, 08:00:08 AM »

This guy got some serious airtime.  Conveniently, the driver landed in a graveyard...

Car Slams Into Roundabout, Flies Through the Air, Lands in a Graveyard
https://interestingengineering.com/video/car-slams-into-roundabout-flies-through-the-air-lands-in-a-graveyard

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tradephoric

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Re: Crash prone 'modern roundabouts'
« Reply #2467 on: April 15, 2020, 08:50:09 AM »

In at least one of these projects,  traffic improvement was an objective as NYSDOT even took up an unbearable task of synchronizing traffic lights.  All 3 of them. Apparently, they gave up after realizing this is too much of engineering work to do. 

If driving straight thru all 3 lights, how many do you normally get stopped at?
all 3. I actually tried to look at the phase of a signal ahead and make it non-stop, but it _never_ worked for me.

If NYSDOT has difficulty synchronizing 3 lights I would hate to see how well they would do retiming 124 traffic signals.  In Detroit it’s possible to drive 40 miles and over 100 traffic signals without getting stopped at a red light.  BTW, since this video was taken, the signals along Woodward Avenue were retimed making signal progression even smoother than before.


^It's impossible to see this type of travel time run along a roundabout corridor.  Imagine driving through 124 roundabouts as opposed to 124 traffic signals… that would lead to 124 guaranteed instances of delay (driver drops down to 15-20 mph 124 times to navigate the roundabouts as opposed to cruising 45-50 mph through 124 consecutive green lights).  Hell, after navigating through 124 roundabouts the driver’s brakes would be smoldering! 
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tradephoric

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Re: Crash prone 'modern roundabouts'
« Reply #2468 on: April 16, 2020, 08:23:33 AM »

Hilliard reports roundabout modifications have reduced accidents
https://www.thisweeknews.com/news/20200410/hilliard-reports-roundabout-modifications-have-reduced-accidents

The city of Hilliard reports that roundabout modifications made last summer have helped reduce accidents.  This could be big as the modifications did not include reducing the capacity of the roundabout by eliminating circulating lanes inside the roundabout (which at other complex roundabouts has been the main way at seeing big reduction in crashes).  The main modification made at the 2x1 Main and Scioto Darby roundabout was converting the central island from a circle to an oval (and not with just pavement markings but with raised curbing). 


The modifications made at the 2x2 Main and Cemetery roundabout included raised crosswalks, changes to lane markings, overhead signs and the placement of signs with red LEDs in the central island of the roundabout that indicates drivers must yield to both lanes of traffic before entering the roundabout.  In the picture below you can see they used double dashed white lines and an additional thru arrow at the exiting leg of the roundabout to help reiterate to drivers that a “straight arrow” means you are exiting the roundabout and not continuing around the circle. 


Letty Schamp who is the Deputy City Engineer for the City of Hilliard put together a great presentation that highlights the lessons learned at Hilliard roundabouts.  It highlights the fact that 2x2 roundabouts are very differently from 2x1 roundabouts and that a better job of differentiating between the two needs to be done.  It highlights the ONGOING crash problem that exists at these complex Hilliard roundabouts (and just wishing away crashes doesn't always work).  It highlights the fact that drivers can interpret signage and lane markings very differently from each other causing confusion.  It highlights the fact that engineers lose credibility when they disregard huge increases in PDO crashes and focus almost entirely on the reductions in injury crashes (even when the reductions in injury crashes at some of these complex roundabouts may be quite low).  To their credit the engineers in Hilliard understand the problems associated with complex 2x2 roundabouts and are trying to improve them.

12 Roundabouts in 12 Years:  Lessons Learned
http://www.dot.state.oh.us/engineering/OTEC/2018_OTEC_Presentation/Schamp_09.pdf
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jakeroot

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Re: Crash prone 'modern roundabouts'
« Reply #2469 on: April 16, 2020, 02:28:13 PM »

I appreciate Mr Schamp's sense of humor. That was quite a funny presentation!

I wrote a big paper on roundabouts for my last quarter at school. I wasn't required to go very deep into the research, but I focus more on how we changed from circles, like Dupont Circle, into rotaries (like those in Massachusetts), before we got into the early "modern" roundabouts along I-70 in Colorado (particularly those at the Vail junction).

One thing I noticed was that the early modern roundabouts were very British. Short of driving on the left, they were basically just flipped versions of their roundabouts. This extended to basic practices like not having lane lines through the circle, or flaring the entry roadway from one to two or three lanes to maximize throughput at the circle. The practice of "flaring" seems to have died down a bit.

I bring this up because, in the presentation that Mr Schamp gave, he talks about the "honeymoon" years with their early roundabouts, particularly those along Britton Parkway (oddly enough, a roundabout corridor in Lacey, WA as well). He doesn't go into great detail about what exactly he means by this, but I think it's in reference to them just building a bunch of roundabouts, several quite large examples, and not really paying attention to crash data (with the child-rearing years being where they started to notice serious issues). I wouldn't want to suggest that those early roundabouts were somehow superior to the modern FHWA-compliant designs, but what changed at roundabouts, particularly those designed prior to 2009, to those that we we've seen built since the current MUTCD was released? As far as I can tell, the discussion around crashes has only come up majorly in the last ten years, despite 2x2 modern roundabouts having existed in sizeable numbers since the mid-90s.

When I look at some of the older notable roundabouts:

* Long Beach (Los Alamitos) Roundabout: no major changes after major modification in mid-90s.
* Vail roundabouts: some lane lines added
* Avon roundabouts: one entry (of dozens) narrowed; some lane lines but they frequent disappear
* Summerlin, NV (Town Center Dr): right lanes changed to right-only
* Lacey, WA (Britton/Marvin/Willamette): slip lane added, exit lines added (notable because it was in this early video).

So there have been some changes at these roundabouts, but not really anything major. The newest of these (Lacey, WA) was constructed eighteen years ago; collectively, they've experienced well over 100 years of crash data.

I guess, in short, it's funny how some of the roundabouts that have seen the most number of changes seem to have been those built since 2009.
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Occidental Tourist

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Re: Crash prone 'modern roundabouts'
« Reply #2470 on: April 21, 2020, 06:07:23 PM »

Here are some pictures of the new lane controls at the Los Alamitos (Long Beach, CA) Traffic Circle.  We're going to go counterclockwise starting at the 3 o'clock (east) side of the Traffic Circle.


Looking northwest toward the Lakewood Blvd entrance/exit.  Where the roundabout had been effectively three lanes wide and unmarked, striping at the edge and painted lane controls have reduced this portion to two lanes. Three entrance lanes from Los Coyotes Diagonal (right foreground) have been reduced to two by striping a median between the inside and outside entrance lanes.



Approach and new signage for the Lakewood Blvd entrance to the roundabout (now at 12 o'clock looking south).  The dedicated right turn lane from Lakewood Blvd to PCH westbound has been kept.  Not pictured are the flexible stakes that have been added to this dedicated right turn lane to delineate it from the rest of the roundabout.  Prior to this, this dedicated right turn lane was delineated from the rest of the roundabout by just a solid white line.



Lakewood Blvd approach again.  Two entrance lanes and a dedicated right turn lane have been reduced to two entrance lanes through striping.



New signage and striping for the eastbound PCH entrance (9 o'clock looking east).


At the eastbound PCH entrance looking north towards Lakewood Blvd.  An asphalt curb/truck apron has been installed here along with pavement striping to reduce the roundabout to one lane here.  This is the only point where the roundabout is one lane.  All other sections are two lanes wide.


(At 6 o'clock now) Looking northeast toward the Los Coyotes Diagonal in the distance.  The dedicated right turn lane from PCH eastbound to PCH southeastbound has been kept.  Flexible stakes have been added to separate the dedicated lane from the remainder of the roundabout.  Previously, only a solid white line delineated the dedicated right turn lane.  On the east side of the roundabout, an asphalt curb/truck apron has been added to the inside of the roundabout to reduce the overall width to two lanes.



Returning to the east side of the roundabout again (3 o'clock again).  Obviously, not all entrances and exits are uniform.  But here's an odd pavement lane control between the PCH northwestbound entrance and the Los Coyotes Diagonal exit.  I don't think the arrows in the right lane are accurate (two of the arrows are superfluous).  This lane control probably should have been painted back in the right entrance lane from northwest bound PCH (offscreen left). A similar arrow (not pictured) also has been painted on the right side near the Lakewood Blvd exit.


Still on the east side, here's entrance from northwestbound PCH to the roundabout.  It seems to be the only entrance from which the righthand lane has to cross over two exit lanes to enter the roundabout. 

Now that the Los Alamitos Traffic Circle has gone from laissez faire to having lane controls, we'll have to see how the accident rate at it fares.
« Last Edit: April 21, 2020, 06:14:37 PM by Occidental Tourist »
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Re: Crash prone 'modern roundabouts'
« Reply #2471 on: May 17, 2020, 07:37:07 PM »

Here are some pictures of the new lane controls at the Los Alamitos (Long Beach, CA) Traffic Circle.  We're going to go counterclockwise starting at the 3 o'clock (east) side of the Traffic Circle.

I'm not sure how I missed this post.

I was just thinking the other day that the Los Alamitos Circle had not been modified from its original configuration since it was updated in 1994. That update in 1994 made it match British standards, with lane-control arrows before the roundabout but without lane markings. But my impression was that it had not been modified since because crashes hadn't become a hysterical issue like at other roundabouts. Part of me was contributing this to the vagueness of the circulating roadway (no lane lines might mean that drivers are a bit less careless, although I don't know this to be fact). I guess it's a bit disappointing to see that it has been modified, since it was one of the few unmodified 90s-era modern roundabouts; could be that those along I-70 in the Rockies are the last of this dying breed.

Part of me genuinely thinks crashes will go up, since all they've done is paint it to look like the numerous other multi-lane modern roundabouts that almost all universally perform poorly in terms of overall crashes. But I guess only time will tell.
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Re: Crash prone 'modern roundabouts'
« Reply #2472 on: June 29, 2020, 07:07:12 PM »

The most crash prone intersection in Michigan in 2019 was the 18 ½ Mile Road and Van Dyke Ave roundabout which saw 229 crashes (a 62% increase in crashes from the year before).  I think 229 annual crashes at a roundabout is a record for this thread

Michigan’s Most Dangerous Intersections in 2019
https://www.michiganautolaw.com/blog/2020/06/23/michigans-most-dangerous-intersections-2019/
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Re: Crash prone 'modern roundabouts'
« Reply #2473 on: June 29, 2020, 10:47:56 PM »

The most crash prone intersection in Michigan in 2019 was the 18 ½ Mile Road and Van Dyke Ave roundabout which saw 229 crashes (a 62% increase in crashes from the year before).  I think 229 annual crashes at a roundabout is a record for this thread

Michigan’s Most Dangerous Intersections in 2019
https://www.michiganautolaw.com/blog/2020/06/23/michigans-most-dangerous-intersections-2019/

Pretty good proof that old roundabouts don't necessarily improve in time.
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BrynM65

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Re: Crash prone 'modern roundabouts'
« Reply #2474 on: June 30, 2020, 09:32:33 AM »

I've not read the entire 99 pages so please forgive me if I am retreading old ground. I'll describe for driving on the right hand side of the road.

British style multi-lane roundabouts cause us no end of safety problems either due to high circulating speeds and low gap availability to merge into. This means entering traffic that has spent a while at the yield line tends to take a gamble and cut in front of others. The traditional two bridges over a freeway roundabouts with a straight section linked by curves are notoriously prone to this and as a result often end up under part time or complete signal control. This gets rid of the entry problems but at the cost of increasing delays on all arms.

The main driver of safety at any large roundabout is to ensure drivers are in the correct lane before entering, and that the lane markings direct drivers to their desired exit with no lane change necessary. This is not always achievable because you may need to move traffic towards the central island in a "spiral" layout but these moves to the left have fewer conflict potentials than moves across to the right.

DDIs and other advanced signal configurations are in my view much better than the traditional two bridge roundabouts. Minimise the conflict points and ensure speeds are at an appropriate level and that's how you reduce collisions.

The Michigan examples seem to have some design flaws but they could be partially fixed relatively cheaply by introducing visibility screens to prevent "reading through" and forcing traffic to yield as a consequence.
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