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Crash prone 'modern roundabouts'

Started by tradephoric, May 18, 2015, 02:51:37 PM

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jakeroot

Quote from: tradephoric on December 27, 2024, 02:42:38 PMThe City of Fishers built a new complex 2x2 roundabout to replace the Michigan Left intersection at 96th Street and Andersonville.  Drivers are complaining about how long it's taking to make it through the intersection now that the roundabout is complete.


Carmel built a bunch of single lane and simple (1x2) multi-lane roundabouts over the past 25 years.  But the need for complex 2x2 and 2x3 roundabouts was largely avoided since the City decided to grade separate their major corridors (Meridian Street & Keystone Pkwy).  Now Fishers is getting in on the fun, but unlike Carmel they are not grade-separating their major corridor along Allisonville Road.  They just completed a complex 2x2 roundabout at 96th and Allisonville and they are planning an even more complex/busy roundabout at 116th and Allisonville Road this Spring.  These are the type of roundabouts where you see triple digit crashes per year.  Not all roundabouts are created equal, and Fishers is really pushing the limits to how big and complex you want to build these. 

Stuff like this makes me seriously question city budgets. That intersection was completed as a Michigan Left barely 12 or 13 years ago. To my knowledge, it operated just fine, especially with the double left flashing yellow arrows at U-turn points (one lane for U-turn, the other for lefts), and simple phasing at the primary intersection. Needless to say, it did not need to be rebuilt into a roundabout, certainly not in the way that it was, with insane path overlap for two of the cross-over points.

And the city engineer is blaming diversion from nearby freeway construction for the traffic? There may be truth to that, but that nearby construction is not new, yet the old intersection handled it all just fine.

There was no pressing need for reconstruction here, hence my questioning of the Fishers budget. I have spent a great deal of time in the city (as well as McCordsville and Carmel), and while I recognize that these cities are growing rapidly with high overall income and thus lots of income for various city projects, I feel like whatever was spent here could have been spent rebuilding literally a hundred other intersections. Off the top of my head, literally any other intersection along Allisonville could have received a roundabout, and it would have made more sense.


jakeroot

Quote from: cjw2001 on December 27, 2024, 09:19:07 PM...some of the issue is also the Indianapolis driver base which is much less familiar with roundabouts than their Hamilton county counterparts.  I would expect this to improve with time as those drivers become used to the intersection.

With all due respect, this is an absurd take. Between Carmel and Fishers, this area has well over 150+ roundabouts. Just because this one single census block doesn't have a dozen roundabouts doesn't mean you get to excuse drivers from failing to understand how to drive in them. I mean, 96th alone has 11 roundabouts along it. While Allisonville might not have any, I highly doubt the average Allisonville driver never ventures into Carmel or Fishers, given how much commercial activity is in both cities.

The only potential area of confusion might be the reintroduction of left turns to the intersection. But that's only so much of an excuse. Confusion from not understanding roundabouts is simply not a good excuse anymore. Sorry.

Quote from: mrsman on December 29, 2024, 05:40:18 PMCan someone explain the terminology used for roundabouts like 1X2 and 2X2 and 2X3?  What does each number represent, the number of lanes entering the roundabout or the number of lanes in the roundabout itself?

The numbers represent the number of circulatory lanes at a roundabout. Typically, roundabouts are symmetrical, so you'll have, for example, one lane going north and south through a roundabout, and two lanes going east and west. This would be a 1x2 roundabout (1 lane for one road, 2 lanes for the other road). Two lanes for all approaches would be a 2x2 roundabout, and so on.

cjw2001

Quote from: jakeroot on January 01, 2025, 02:23:23 AM
Quote from: cjw2001 on December 27, 2024, 09:19:07 PM...some of the issue is also the Indianapolis driver base which is much less familiar with roundabouts than their Hamilton county counterparts.  I would expect this to improve with time as those drivers become used to the intersection.

With all due respect, this is an absurd take. Between Carmel and Fishers, this area has well over 150+ roundabouts. Just because this one single census block doesn't have a dozen roundabouts doesn't mean you get to excuse drivers from failing to understand how to drive in them. I mean, 96th alone has 11 roundabouts along it. While Allisonville might not have any, I highly doubt the average Allisonville driver never ventures into Carmel or Fishers, given how much commercial activity is in both cities.

The only potential area of confusion might be the reintroduction of left turns to the intersection. But that's only so much of an excuse. Confusion from not understanding roundabouts is simply not a good excuse anymore. Sorry.

Quote from: mrsman on December 29, 2024, 05:40:18 PMCan someone explain the terminology used for roundabouts like 1X2 and 2X2 and 2X3?  What does each number represent, the number of lanes entering the roundabout or the number of lanes in the roundabout itself?

The numbers represent the number of circulatory lanes at a roundabout. Typically, roundabouts are symmetrical, so you'll have, for example, one lane going north and south through a roundabout, and two lanes going east and west. This would be a 1x2 roundabout (1 lane for one road, 2 lanes for the other road). Two lanes for all approaches would be a 2x2 roundabout, and so on.
No argument that people using the 96th corridor would encounter other roundabouts.  I was thinking more about north/south traffic on Allisonville which had no existing roundabouts before getting into Noblesville.  Never claimed that those drivers have never encountered a roundabout before, but they don't have the same level of experience on this corridor as other major corridors in the area.  This will soon change as new roundabouts are also added at 116th and 146th Streets.

jakeroot

Quote from: cjw2001 on January 01, 2025, 09:22:26 PM
Quote from: jakeroot on January 01, 2025, 02:23:23 AM
Quote from: cjw2001 on December 27, 2024, 09:19:07 PM...some of the issue is also the Indianapolis driver base which is much less familiar with roundabouts than their Hamilton county counterparts.  I would expect this to improve with time as those drivers become used to the intersection.

With all due respect, this is an absurd take. Between Carmel and Fishers, this area has well over 150+ roundabouts. Just because this one single census block doesn't have a dozen roundabouts doesn't mean you get to excuse drivers from failing to understand how to drive in them. I mean, 96th alone has 11 roundabouts along it. While Allisonville might not have any, I highly doubt the average Allisonville driver never ventures into Carmel or Fishers, given how much commercial activity is in both cities.

The only potential area of confusion might be the reintroduction of left turns to the intersection. But that's only so much of an excuse. Confusion from not understanding roundabouts is simply not a good excuse anymore. Sorry.

Quote from: mrsman on December 29, 2024, 05:40:18 PMCan someone explain the terminology used for roundabouts like 1X2 and 2X2 and 2X3?  What does each number represent, the number of lanes entering the roundabout or the number of lanes in the roundabout itself?

The numbers represent the number of circulatory lanes at a roundabout. Typically, roundabouts are symmetrical, so you'll have, for example, one lane going north and south through a roundabout, and two lanes going east and west. This would be a 1x2 roundabout (1 lane for one road, 2 lanes for the other road). Two lanes for all approaches would be a 2x2 roundabout, and so on.
No argument that people using the 96th corridor would encounter other roundabouts.  I was thinking more about north/south traffic on Allisonville which had no existing roundabouts before getting into Noblesville.  Never claimed that those drivers have never encountered a roundabout before, but they don't have the same level of experience on this corridor as other major corridors in the area.  This will soon change as new roundabouts are also added at 116th and 146th Streets.

Okay, fair enough. But to imply that daily use is the only way to gain experience is no less absurd than saying drivers along Allisonville never go through roundabouts; we both know every driver along Allisonville has driven through a roundabout at some point, ~98% likely within the last week, and all should know how to use one. After all, we've been building roundabouts in this country for 35 years.

As an aside, there's likely almost no drivers that regularly drive Allisonville north to south without ever venturing off it. Between Noblesville and anywhere inside the 465 Beltway, you're much better off using 37/I-69, especially with the new grade separation. I suspect Allisonville is mostly used these days as a distributer road for the east-west arterials. For example, going from 96th in Carmel to 116th in Fishers.

tradephoric

This article gives crash stats at the Allisonville & 96th Street when it was a Michigan Left...

Fishers replacing Michigan left intersection with roundabout
https://readthereporter.com/fishers-replacing-michigan-left-intersection-with-roundabout/

QuoteAccording to the Fishers Police Department, the Allisonville and 96th Street intersection experienced eight crashes since 2022, compared with eight crashes at nearby 106th Street over the same time period. The 116th Street and Allisonville Road intersection had 14 crashes between 2022 and 2024.

"Introducing a two-lane roundabout on 96th and Allisonville is going to, No. 1, make it easier for everyone and, No. 2, make it a lot more safer," Meky said.

There were only 8 crashes since 2022 at the Michigan Left yet the director of engineering for Fishers city government thinks this new roundabout is going to make things a lot safer.  I'm not buying it for a second, not for this particular complex roundabout.


kalvado

Quote from: tradephoric on January 03, 2025, 11:56:43 AMThis article gives crash stats at the Allisonville & 96th Street when it was a Michigan Left...

Fishers replacing Michigan left intersection with roundabout
https://readthereporter.com/fishers-replacing-michigan-left-intersection-with-roundabout/

QuoteAccording to the Fishers Police Department, the Allisonville and 96th Street intersection experienced eight crashes since 2022, compared with eight crashes at nearby 106th Street over the same time period. The 116th Street and Allisonville Road intersection had 14 crashes between 2022 and 2024.

"Introducing a two-lane roundabout on 96th and Allisonville is going to, No. 1, make it easier for everyone and, No. 2, make it a lot more safer," Meky said.

There were only 8 crashes since 2022 at the Michigan Left yet the director of engineering for Fishers city government thinks this new roundabout is going to make things a lot safer.  I'm not buying it for a second, not for this particular complex roundabout.


At some point it has to come down to people being held personally responsible for certain decisions. Personally as in personal job and fiscal responsibility, as in demotion and pension cuts. Certain agencies and decisions fully deserve criminal prosecution as well.

cjw2001

Drove through the 96th and Allisonville roundabout at noon today and traffic was flowing smoothly.   Looks like Fishers added the "to Both Lanes" under all the Yield signs within the last few days.

tradephoric

Quote from: cjw2001 on January 04, 2025, 12:35:20 PMDrove through the 96th and Allisonville roundabout at noon today and traffic was flowing smoothly.  Looks like Fishers added the "to Both Lanes" under all the Yield signs within the last few days.

Did the original design call for the "to both lanes" signs be installed under the yield signs?  If not, that could indicate the city is already seeing a crash problem at the roundabout and are already tweaking with the signage. 

According to Fisher's Police there were 29 crashes at the new roundabout between October 29-December 11, 2024 compared to 7 crashes between October 29-December 11, 2023.  At that pace (0.65 crashes per day) the roundabout would average 240 crashes per year.  Not saying it ends up with 240 crashes per year, but the first 44 days of crash data at the new roundabout doesn't exudes confidence.   



 

tradephoric

Massive shunt at the roundabout in the center of Lebanon Tennessee.  Driver seems suicidal going that speed in the middle of town.


mrsman

^^^^^

I guess a fundamental question in design choices between making things safer for the majority of people or making things safer for the egregious violators.  This roundabout seems very reasonable with one lane on each approach.  It doesn't seem like this was ever a regular intersection, as old GSV images show that traffic used to have to go around a square and that the statue has probably also been there a very long time.  It probably is safe when people follow the speed limit and probably efficient as traffic slows/stops without having to wait for a very long time at a long red light.

But of course, it is worse for somebody going 80+ MPH. 

I guess the real question is how often accidents happen at the circle in Lebanon TN.  I won't judge on its safety based on an egregious speed violator as shown.  The individual would have likely run a red light if this was a normal intersection.

tradephoric

Fishers is now considering to delay construction of the roundabout at 116th and Allisonville until INDOT completes construction on I-465.  This comes on the heels of the problematic roundabout that Fishers recently opened at 96th and Allisonville.  When I-465 construction is complete and crashes at the newly built roundabouts are astronomically higher than the intersections they replaced, the city won't have that excuse to fall back on anymore.  They'll just blame the crash problem on something else i'm sure and not admit that these complex roundabouts were a mistake.

https://www.wrtv.com/news/local-news/fishers-considers-delaying-construction-of-another-roundabout-at-116th-and-allisonville

jakeroot

Quote from: tradephoric on February 05, 2025, 12:01:49 PMFishers is now considering to delay construction of the roundabout at 116th and Allisonville until INDOT completes construction on I-465.  This comes on the heels of the problematic roundabout that Fishers recently opened at 96th and Allisonville.  When I-465 construction is complete and crashes at the newly built roundabouts are astronomically higher than the intersections they replaced, the city won't have that excuse to fall back on anymore.  They'll just blame the crash problem on something else i'm sure and not admit that these complex roundabouts were a mistake.

https://www.wrtv.com/news/local-news/fishers-considers-delaying-construction-of-another-roundabout-at-116th-and-allisonville

It's amazing that they are intentionally building intersections that cannot handle their current traffic counts...at least in their own terms. In what world do Midwest suburban communities intentionally rebuild intersections of two major arterials to a lower capacity than it was before? The old intersection worked great and handled the diversion traffic just fine, so clearly the roundabout is the problem here. Without even taking into account crashes.

Obviously they're burying their head in the sand as to the actual problem. The lack of accountability and failure to recognize the idiocy of the current roundabout (the path overlap is absurd for modern FHWA roundabout standards), never mind the obvious crash issues...it's a wonder if their engineering department is actually doing any work, or if they just pump out "roundabout" over and over again on autopilot.

kphoger

Quote from: mrsman on January 09, 2025, 11:38:34 AMI guess the real question is how often accidents happen at the circle in Lebanon TN.

It no longer matters.  This is now the "Anytime there's a crash at any roundabout anywhere for any reason" thread.  He doesn't care if it's actually crash-prone or not.
Keep right except to pass.  Yes.  You.
Visit scenic Orleans County, NY!
Male pronouns, please.

Quote from: Philip K. DickIf you can control the meaning of words, you can control the people who must use them.

english si

Quote from: kphoger on February 07, 2025, 01:57:00 PMIt no longer matters.  This is now the "Anytime there's a crash at any roundabout anywhere for any reason" thread.  He doesn't care if it's actually crash-prone or not.
'no longer', 'now'? When was this thread anything other than what you describe?

kphoger

Back when there were charts and graphs.  Now it's just news article links.
Keep right except to pass.  Yes.  You.
Visit scenic Orleans County, NY!
Male pronouns, please.

Quote from: Philip K. DickIf you can control the meaning of words, you can control the people who must use them.

D-Dey65

Quote from: 6a on May 19, 2015, 04:16:01 PM
This particular photo is an example of why I've had a problem with them. Whenever roundabouts are built, they're frequently done with the roads shifted out of the original right-of-way before finally reaching the circles themselves. It might seem like a minor issue, but if it contributes to accidents within them, it's a serious design flaw. Far too often though what I see is the notion that the people who make them assume that drivers are always going to be courteous to each other when approaching them, and too often they aren't.


cjw2001

Quote from: D-Dey65 on February 08, 2025, 06:42:29 AM
Quote from: 6a on May 19, 2015, 04:16:01 PM
This particular photo is an example of why I've had a problem with them. Whenever roundabouts are built, they're frequently done with the roads shifted out of the original right-of-way before finally reaching the circles themselves. It might seem like a minor issue, but if it contributes to accidents within them, it's a serious design flaw. Far too often though what I see is the notion that the people who make them assume that drivers are always going to be courteous to each other when approaching them, and too often they aren't.


What does courtesy have to do with driving a roundabout?  Absolutely nothing.  It is a legal requirement to yield to traffic - there is no opportunity to decide to let others through out of turn.  That would lead to chaos.

Rothman

The curves into the roundabout are also intended to encourage drivers to slow down.

Still in the camp if there are drivers out there that think they don't have to pay attention to the road that they should't be behind the wheel.
Please note: All comments here represent my own personal opinion and do not reflect the official position(s) of NYSDOT.

kalvado

Quote from: cjw2001 on February 09, 2025, 11:11:22 AM
Quote from: D-Dey65 on February 08, 2025, 06:42:29 AM
Quote from: 6a on May 19, 2015, 04:16:01 PM
This particular photo is an example of why I've had a problem with them. Whenever roundabouts are built, they're frequently done with the roads shifted out of the original right-of-way before finally reaching the circles themselves. It might seem like a minor issue, but if it contributes to accidents within them, it's a serious design flaw. Far too often though what I see is the notion that the people who make them assume that drivers are always going to be courteous to each other when approaching them, and too often they aren't.


What does courtesy have to do with driving a roundabout?  Absolutely nothing.  It is a legal requirement to yield to traffic - there is no opportunity to decide to let others through out of turn.  That would lead to chaos.
Not exactly courtesy, but decisions on gap being big enough to merge can be more or less aggressive. For some busier ones, having a thickness of a newspaper between bumpers as a minimum separation may be a necessary evil.

jakeroot

Quote from: kphoger on February 07, 2025, 02:23:26 PMBack when there were charts and graphs.  Now it's just news article links.

For the most part, the news articles are about roundabouts that are nearly brand new or within a year or two of having been built. Does it not strike you as odd that a new roundabout touted for its ability to reduce crashes and serious injuries/deaths does, in fact, do neither?

Besides that, what do you want, a continuous supply of charts and graphs from trade? He presented his data already, and it was very telling: multi-lane roundabouts have a higher crash rate than single-lane roundabouts, but are built by agencies as though they have the same crash statistics as single-lane roundabouts, even though they don't.

Agencies have begun to shift away from touting them as resulting in "fewer crashes" and more towards "less deaths and serious injuries". And there may be truth to that, even with larger multi-lane roundabouts. But that's moving the goalposts at a minimum, while also completely ignoring the issue of skyrocking property-damage crashes at so many of them.

In some cases, these roundabouts have a lot of crashes in the first year or two, and then start to level out. But in many other cases, the roundabouts have to have lane reductions just to cut down on the number of crashes (and in doing so, also the number of conflict points). In other cases, perhaps the intersection went from one or two deaths to zero, but to say the roundabout eliminated that/those death(s) from occurring again is highly speculative and specious; you could blame numerous variables for there not being roadway fatalities.

tradephoric

#2970
Here are the stated safety benefits of Median U-Turn intersections (MUTs) and Reduced Conflict Intersections (RCIs)  taken directly from the Indiana Department of Transportation website:

QuoteImproved Safety
MUT intersections significantly reduce the risk of severe crashes in certain traffic and road conditions. MUTs increase safety by reducing by half or more the number of possible conflicts and the points where two vehicle paths cross.

In a traditional intersection there are 42 different conflict points where an accident can occur. Of those, 24 conflict points can cause serious T-bone or right angle crashes – the crashes most responsible for fatalities and serious injuries at intersections. A MUT intersection can have no more than 29 possible conflict points and some MUT intersections can be designed so that there are zero crossing conflict points.

RCIs eliminate the need for motorists to cross the high-speed lanes of traffic to get to the opposing lanes. Nationwide, statistics show a more than 50% decline in crashes where RCIs are installed. Fatal crashes decline by as much as 85%.

Recent Statistics
Since 2015, INDOT has installed seven RCIs at four-lane highway intersections in Indiana. These intersections have shown a substantial decrease in fatal and injury crashes since RCI installation.

INDOT has conducted performance analyses of crashes at each RCI, comparing pre-construction crash frequency and severity with post-construction data over similar time periods, ranging from 1½ to 5 years.

In overall effectiveness, INDOT's analysis showed that the seven RCIs:

Reduced fatal and injury crashes by an average of 81%.
Reduced property-damage crashes by an average of 58%.
Reduced crashes of any severity by an average of 68%.
INDOT's analysis showed a dramatic reduction in fatal and injury vehicle crashes at each RCI:

Fatal and injury crashes at each intersection declined between 64% and 100%.
Property-damage crashes at each intersection ranged from No Change to 100% reduction.
All crashes of any severity at each intersection declined between 38% and 100%.
INDOT continues to track the safety performance of these and future RCIs to assess their effectiveness and advance our understanding of the traffic levels, design, and site conditions most suitable for this highway feature.
https://www.in.gov/indot/traffic-engineering/median-u-turns/

Based on INDOTs analysis there was a dramatic 81% reduction in fatal and injury crashes at the reduced crossing intersections (RCIs) studied.  The improved safety benefits a roundabout would provide doesn't apply when you are replacing an innovative intersection with a roundabout (since innovative intersections that eliminate direct left-turns already provide dramatic safety benefits).

Considering 96th Street and Allisonsville intersection in Fishers had been an innovative intersection with a proven safety record, was it really the best use of resources to replace it with a complex roundabout?

tradephoric

#2971
Reddit threads discussing the new roundabout in Fishers...

What was so bad about the "Michigan Left" at 96th and Allisonville? Did you honestly ever have trouble with it?
https://www.reddit.com/r/indianapolis/comments/1i9mda5/what_was_so_bad_about_the_michigan_left_at_96th/

E. 96th St. and Allisonville Rd. has experienced one car accident per day since the start of the year😬
https://www.reddit.com/r/Fishers/comments/1i0f5y3/e_96th_st_and_allisonville_rd_has_experienced_one/

3 accidents today at Allisonville Road and 96th st Roundabout.. we might get over 30 accidents this month
https://www.reddit.com/r/Fishers/comments/1id6fd4/3_accidents_today_at_allisonville_road_and_96th/

Dangerous roundabout on 96th & Allisonville Rd. Please read and sign if you agree 👇🏻
https://www.reddit.com/r/Carmel/comments/1ijy811/dangerous_roundabout_on_96th_allisonville_rd/


JayhawkCO

I have no particular opinion about roundabouts. I'm only interrupting this thread to post that the Swahili word for roundabout is 'kipilefti'.

That is all.

kphoger

Quote from: jakeroot on February 10, 2025, 05:18:58 AMFor the most part, the news articles are about roundabouts that are nearly brand new or within a year or two of having been built. Does it not strike you as odd that a new roundabout touted for its ability to reduce crashes and serious injuries/deaths does, in fact, do neither?

Honestly, it surprises me if serious injuries/deaths are not reduced, but it does not surprise me if crashes are not reduced.  But that's not the point.  The point is that recently constructed roundabouts are are too new to have revealed any trend, positive or negative, in the number of crashes/injuries/deaths at the intersection.

Quote from: jakeroot on February 10, 2025, 05:18:58 AMHe presented his data already, and it was very telling: multi-lane roundabouts have a higher crash rate than single-lane roundabouts, but are built by agencies as though they have the same crash statistics as single-lane roundabouts, even though they don't.

Agreed.  That's precisely what I consider to be the chief contribution of this thread to our knowledge base about roundabouts, and he did an excellent job of teasing that reality out of the data.

But that was years ago.

Quote from: jakeroot on February 10, 2025, 05:18:58 AMBesides that, what do you want, a continuous supply of charts and graphs from trade?

No.  But it's OK to let a thread die out until there's something of substance to add to it.  There hasn't really been anything in this thread about what is crash-prone for a long time.  And that's OK.  If the thread exhausted the topic, then it has succeeded.  Just let it go.
Keep right except to pass.  Yes.  You.
Visit scenic Orleans County, NY!
Male pronouns, please.

Quote from: Philip K. DickIf you can control the meaning of words, you can control the people who must use them.

tradephoric

Quote from: kphoger on February 07, 2025, 01:57:00 PM
Quote from: mrsman on January 09, 2025, 11:38:34 AMI guess the real question is how often accidents happen at the circle in Lebanon TN.

It no longer matters.  This is now the "Anytime there's a crash at any roundabout anywhere for any reason" thread.  He doesn't care if it's actually crash-prone or not.

I'll sprinkle in the occasional video of a driver launching over a roundabout and coming to rest the next county over on occasion.  Does that take away from the fact there are complex roundabouts being built to this day with very high crash rates?  The roundabout in Fishers being the latest example.  As long as engineers continue to design these complex roundabouts that experience triple-digit crashes per year, I'll continue to mention them. 



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