Crash prone 'modern roundabouts'

[tradephoric]

What exactly is the continued purpose of this thread?

There is continued roundabout research to discuss.  Several articles of trucks tipping over at roundabouts have been posted but also research that looks at potential counter measures to prevent truck tip-overs has been posted.   I'm not suggesting we rip out that Worthington roundabout because two trucks tipped-over during a two week period last month, but maybe there are ways to prevent them.  A presentation was given at the roundabout conference in Green Bay this year that was entitled "Geometric Parameters that Affect Truck Stability" .  In the presentation the RI (Rollover Index) decreased when the ICD increased, the RI was lower in the right lane than the left lane of the roundabout, the RI decreased most significantly when lowering truck speed from 15 mph to 10 mph, the RI was lower with crowned section than with constant outer slope, and a higher rollover risk was associated with 3-inch vertical face truck aprons.  Other counter measures to slow traffic down include the use of optical speed bars and rumble strips along the roundabout approaches.
 

Will posting enough articles about roundabout accidents somehow prevent future ones from being built?

Accidents at roundabouts can have an effect on future plans.  As I mentioned the region of Waterloo scrapped plans to build a major roundabout next to a high school on Franklin Blvd. in Cambridge largely due to Cassi Lam getting hit by a bus in the crosswalk shortly after the Block Line roundabout opened in Kitchener.  Her injury accident made the public question if a roundabout was a good idea at high pedestrian traffic locations.  Fast forward to today and the region just constructed another large roundabout at Ottawa Street and Homer Watson similar to the Block Line roundabout design.  It has much less pedestrian traffic as it is not right next to a high school, but two bicyclists have already been hit in the roundabout within a month of opening.  Much of the reason these roundabouts have been built is because city leaders have stated the roundabouts would be safer.  People in the community have every right to question if that's the case.

What actions are you guys taking other than cruising google for articles that fit your views and saying it proves you right?

About 20 years ago the IIHS proclaimed that roundabouts are safer than traditional signalized intersections.  Are we just supposed to assume that it is "˜settled science' and never cite anything that contradicts this general belief?  It's one thing to look at roundabouts in general and say they are safer but not all roundabouts are created equal.  I have long argued that complex roundabouts with 2x2 or higher geometries have high crash rates and that reductions in injury crashes at these types of roundabouts are questionable.  The Ellsworth roundabout in Ann Arbor experienced a 10 fold increase in crashes after the roundabout was completed.  But that is just one location and maybe it's a total fluke.  Then you hear that the 2x2 roundabouts analyzed in the Minnesota study saw a 200% increase in total crashes and a 6.2% increase in INJURY crashes.  There has to reach a point where you question if certain complex roundabouts are safer.  I just find it humorous when a complex roundabout has nearly 200 crashes in a year, and people will just say "yeah but it's safe because it's a roundabout" . 

Do you deliberately avoid any roads that have them in use?

The IIHS is such a reputable organization that has shaped public opinion that roundabouts are safer.  Remember, it's a roundabout so it must be safe!  Well if you believe that, they also researched two roundabouts in Bellingham, Washington and found that drivers 70 years and older were less likely to travel through the roundabouts and would find alternative routes to avoid it. 

Personally I have avoided driving on roundabout corridors if I didn't feel like slowing down, speeding up, slowing down, and speeding up again.  I mentioned that this weekend I drove for 40 miles without hitting a red light along a major corridor in Detroit, cruising through 122 consecutive green lights.  Why would I want to drive through a bunch of roundabouts when I can just cruise through 122 consecutive green lights?  It's a lot more convenient then having to slow down for every roundabout you come to. 

[7/8]

It's unfortunate what happened to Cassi Lam. I went to St. Mary's High School and she was actually in my class, so unlike most accidents, this one felt more personal. I can see why pedestrians are scared to use roundabout crosswalks. Entering vehicles have lots of time to see pedestrians and the tight curve entering the roundabout forces them to slow down. But exiting the roundabout, you have a much shorter distance to notice the pedestrian waiting to cross, and there's less of curve, encouraging faster exit speeds. I don't use the infamous Homer Watson/Block Line roundabout often, but I used it once this summer and I blew by a pedestrian waiting to cross. By the time I saw them, I felt like I was going to fast to stop (thankfully they didn't start crossing!). It's tough though, since I still like roundabouts. They often seem to be more efficient than traffic lights, and I prefer stopping briefly (or slowing down) every time to drive through a roundabout then sometimes getting stuck waiting for minutes at a red light.

I think larger roundabouts with sharp turns at both the entrance and the exits would help slow people down, making it easier to stop for pedestrians. Of course, this would require more land, so I can understand why this may not be practical in a lot of cases. I also wonder if there are other downsides to larger roundabouts (other than increased travel time)?

Changing the topic a bit, I find this roundabout in Arthur, ON to be poorly designed: https://www.google.ca/maps/@43.83622,-80.532375,297m/data=!3m1!1e3 (unfortunately there's no street view).
They made it very small to fit in the available right-of-way, but it's so small that you can go straight through it without turning!

[cjw2001]

Posting this before tradephoric does his google search of the day....

There was a motorcycle crash at one of the Hazel Dell roundabouts in Carmel today.   The motorcycle was fleeing police at high speed after refusing to pull over for a traffic stop.   Somehow I'm sure he will say this was the roundabout's fault as well.   

[jakeroot]

Changing the topic a bit, I find this roundabout in Arthur, ON to be poorly designed: https://www.google.ca/maps/@43.83622,-80.532375,297m/data=!3m1!1e3 (unfortunately there's no street view).
They made it very small to fit in the available right-of-way, but it's so small that you can go straight through it without turning!

Reminds me of those mini roundabouts in the UK, where going through without turning much is quite common. In other European countries, especially France for whatever reason, the traversable area of the roundabout is so wide, many allow you pass right through without hardly turning your wheel. See here (west to east movement): https://goo.gl/tCyV1H

[tradephoric]

Posting this before tradephoric does his google search of the day....

There was a motorcycle crash at one of the Hazel Dell roundabouts in Carmel today.   The motorcycle was fleeing police at high speed after refusing to pull over for a traffic stop.   Somehow I'm sure he will say this was the roundabout's fault as well.   

The motorcyclist was critically injured.  Cjw2001, have you been able to find the last time someone was killed at a Carmel traffic signal?  I know Carmel is known as the roundabout capital of America but to this day traffic signals still exist in the city.   There have been 5 documented fatalities at Carmel roundabouts over the past decade but not a single documented fatal crash at a traffic signal (let alone 5 of them).  I figured you would have some idea when the last fatality happened at a traffic signal in Carmel.  An important thing to keep in mind is there were more traffic signals than roundabouts in Carmel a decade ago (in fact not a single roundabout had been built along Meridian Street or Keystone Pkwy back in 2007).

Documented fatalities in Carmel over the past decade....
Roundabouts = 5 fatalities
Traffic signals = 0 fatalities

[jeffandnicole]

Posting this before tradephoric does his google search of the day....

There was a motorcycle crash at one of the Hazel Dell roundabouts in Carmel today.   The motorcycle was fleeing police at high speed after refusing to pull over for a traffic stop.   Somehow I'm sure he will say this was the roundabout's fault as well.   

The motorcyclist was critically injured.  Cjw2001, have you been able to find the last time someone was killed at a Carmel traffic signal?  I know Carmel is known as the roundabout capital of America but to this day traffic signals still exist in the city.   There have been 5 documented fatalities at Carmel roundabouts over the past decade but not a single documented fatal crash at a traffic signal (let alone 5 of them).  I figured you would have some idea when the last fatality happened at a traffic signal in Carmel.  An important thing to keep in mind is there were more traffic signals than roundabouts in Carmel a decade ago (in fact not a single roundabout had been built along Meridian Street or Keystone Pkwy back in 2007).

Documented fatalities in Carmel over the past decade....
Roundabouts = 5 fatalities
Traffic signals = 0 fatalities

Easy enough to find: http://www.nixle.us/alert/5777716/

Oh, wait, you specifically said traffic signal intersections to exclude intersections without traffic signals, which appears to be the case of this accident.  Guess we need to narrow our focus a bit to meet your agenda.

[kalvado]

Oh, wait, you specifically said traffic signal intersections to exclude intersections without traffic signals, which appears to be the case of this accident.  Guess we need to narrow our focus a bit to meet your agenda.

Sure, if roundabouts were positioned where they belong - to intersections with too much traffic for a stop/yield sign flow control, yet with too little for full signal - we should be comparing roundabouts to non-signalized intersections.
Unfortunately, we have roundabouts built where traffic signals have hard time handling traffic - that is, 30k+ daily traffic.
But of course to meet your agenda, you would show how safe low traffic roundabouts are.
Trade seems to be somewhat more honest person in this context. Agenda-driven like everyone is these day,  but still a bit more honest.

[kphoger]

Easy enough to find: http://www.nixle.us/alert/5777716/

Oh, wait, you specifically said traffic signal intersections to exclude intersections without traffic signals, which appears to be the case of this accident.  Guess we need to narrow our focus a bit to meet your agenda.

They should never have planted trees along there.  It's their job to plan for idiot drivers who run off the side of the road.

[kalvado]

Easy enough to find: http://www.nixle.us/alert/5777716/

Oh, wait, you specifically said traffic signal intersections to exclude intersections without traffic signals, which appears to be the case of this accident.  Guess we need to narrow our focus a bit to meet your agenda.

They should never have planted trees along there.  It's their job to plan for idiot drivers who run off the side of the road.

Of course it is. Divided highways and guardrails are simple examples of such planning.
Always remember - you're not the only idiot behind the steering wheel (c)my driving instructor

[tradephoric]

A signalized corridor leads to platooning where a group of vehicles are traveling in packs.  Conversely, a roundabout breaks up platoons and traffic exits the roundabout more sporadically.  Imagine a scenario where a driver is trying to make a left out of an unsignalized sub-street.  Do roundabouts help or hurt their chances of pulling out of their sub safely?  Once a roundabout is complete drivers at nearby sub-streets will often complain that there isn't enough gap to pull out of the sub.  Imagine a scenario where a roundabout reduces injury crashes by 30% but mid-block injury crashes increases by 50%.  Would the roundabout still be seen as a safety improvement? 

See Walker's new I-12 roundabout in action; residents, police call it 'confusing'
http://www.theadvocate.com/baton_rouge/news/communities/livingston_tangipahoa/article_6d52d828-d611-11e7-9582-8f8dcc4fe95f.html

Watch the video of the new I-12 roundabout along Walker Road.  Admittedly one of the off-ramp lanes is still coned off which is greatly reducing the capacity of the roundabout.  But look how off-ramp traffic is backing up onto the freeway.  Do you think that this will be the only time that the off-ramp will experience lane restrictions?  Maybe in stasis that would be true, but this is the real world.  At least with a traffic signal you can favor the off-ramp traffic and give them more time if there are lane restrictions (so that off-ramp traffic don't back up onto the freeway).  With an unsignalized roundabout you can't do that.  But don't worry the roundabout is safe.. nevermind the family in a mini-van that just got rear-ended by a semi on the freeway. 

[kphoger]

A signalized corridor leads to platooning where a group of vehicles are traveling in packs.  Conversely, a roundabout breaks up platoons and traffic exits the roundabout more sporadically.  Imagine a scenario where a driver is trying to make a left out of an unsignalized sub-street.  Do roundabouts help or hurt their chances of pulling out of their sub safely? 

Depends on the traffic volumes coming from each signal phase of the nearest stoplights both up- and downstream of the intersection.  Stoplights do not simply stop all traffic and then allow all traffic to go.  To turn left out of my bank, for example, I need to wait for [1] nearside through traffic from the left to clear; [2] then nearside right-turning traffic to clear (which had previously been waiting, and which often keeps flowing until the next signal phase); [3] and then protected left-turning traffic to clear.  By the time all of that happens, my gap on the far side of the road has often already been filled by some phase or other of the signal on my right, and all hope is lost.

In this case, a roundabout may or may not help.  I don't know.  But the platooning of vehicles caused by stoplights doesn't necessarily lead to useful gaps for left-turning traffic.

[tradephoric]

WisDOT is considering a roundabout for Rhinelander at highways 8 and 47.
http://www.rivernewsonline.com/main.asp?SectionID=6&SubSectionID=47&ArticleID=79609&PollID=678&btnView=1

According to officials there have been 28 accidents at the intersection between 2012 and 2016 resulting in one fatality and eight injuries.  Half of the accidents were caused by vehicles turning left into the path of oncoming traffic.  Do you really need to put a roundabout in to fix that problem?  If you look at the aerial of the existing intersection (https://www.google.com/maps/@45.63114,-89.43786,19z/data=!3m1!1e3) the left turn bays are offset so somebody trying to make a left-turn can't see past the vehicle in the opposing left turn lane.  Simply realigning the left turn lanes (which is another option on the table) could greatly improve sight distances for left-turning vehicles and cut down on these dangerous head-on-left-turn crashes.

There are many ways to improve the safety of an intersection that don't involve building a roundabout.  Innovative intersections that eliminate left turns at the main-intersection can greatly improve safety.  Various studies have shown that signalized Median U-Turn Intersection Treatments (MUTITs) reduced injury crashes by as much as 75%.  Compare that to the Minnesota study where 2x2 roundabouts actually saw a 6% increase in injury crashes.  And unlike complex roundabouts, Median U-Turns can handle high traffic volumes without several fold increases in total crashes.  But the perception is that signals are dangerous and roundabouts are safe.  That's why agencies keep pushing roundabouts and largely ignore any signalized alternative... WisDOT isn't pushing for a roundabout outright at this intersection, so maybe the perception is slowly changing.

[kphoger]

So...  It's not actually a crash-prone modern roundabout.  Because it hasn't even been built yet.

Side note:  Apparently, I can only go to the article linked once without subscribing.

[jeffandnicole]

WisDOT is considering a roundabout for Rhinelander at highways 8 and 47.
http://www.rivernewsonline.com/main.asp?SectionID=6&SubSectionID=47&ArticleID=79609&PollID=678&btnView=1

According to officials there have been 28 accidents at the intersection between 2012 and 2016 resulting in one fatality and eight injuries.  Half of the accidents were caused by vehicles turning left into the path of oncoming traffic.  Do you really need to put a roundabout in to fix that problem?  If you look at the aerial of the existing intersection (https://www.google.com/maps/@45.63114,-89.43786,19z/data=!3m1!1e3) the left turn bays are offset so somebody trying to make a left-turn can’t see past the vehicle in the opposing left turn lane.  Simply realigning the left turn lanes (which is another option on the table) could greatly improve sight distances for left-turning vehicles and cut down on these dangerous head-on-left-turn crashes.

There are many ways to improve the safety of an intersection that don’t involve building a roundabout.  Innovative intersections that eliminate left turns at the main-intersection can greatly improve safety.  Various studies have shown that signalized Median U-Turn Intersection Treatments (MUTITs) reduced injury crashes by as much as 75%.  Compare that to the Minnesota study where 2x2 roundabouts actually saw a 6% increase in injury crashes.  And unlike complex roundabouts, Median U-Turns can handle high traffic volumes without several fold increases in total crashes.  But the perception is that signals are dangerous and roundabouts are safe.  That’s why agencies keep pushing roundabouts and largely ignore any signalized alternative... WisDOT isn't pushing for a roundabout outright at this intersection, so maybe the perception is slowly changing.

As there's a public comment period, you are more than welcome to put in your opinion. 

[kalvado]

WisDOT is considering a roundabout for Rhinelander at highways 8 and 47.
http://www.rivernewsonline.com/main.asp?SectionID=6&SubSectionID=47&ArticleID=79609&PollID=678&btnView=1

[....]

As there's a public comment period, you are more than welcome to put in your opinion.

I wonder if a non-local input is welcomed, and if these hearings are anything more than a required procedure not affecting anything.
And the real question is why a big and expancive build is chosen when a more simple alternative actually exists. Maybe Wisconsin has budget surplus?

[jeffandnicole]

WisDOT is considering a roundabout for Rhinelander at highways 8 and 47.
http://www.rivernewsonline.com/main.asp?SectionID=6&SubSectionID=47&ArticleID=79609&PollID=678&btnView=1

[....]

As there's a public comment period, you are more than welcome to put in your opinion.

I wonder if a non-local input is welcomed

It'll probably be ignored.

and if these hearings are anything more than a required procedure not affecting anything.

That depends on the project, the agency, the quality of the responses, and who is responding.  Elected politicians generally have the most pull.  Residents that can support their responses with something that doesn't start with "Everyone" may have some pull.  Certain agencies do have their mind made up, and the hearing is a necessary evil.

And the real question is why a big and expancive build is chosen when a more simple alternative actually exists. Maybe Wisconsin has budget surplus?

Because there's supposed to be more going into these projects than what can be done today to solve yesterday's problems.  What appears 'simple' via a glance at an aerial picture may have more to it. 

Also, being that the 'Do Nothing' option is the cheapest option, that must mean every state with work going on must have budget surpluses, right?

Most often, the cheapest option isn't going to be the best option because of numerous other factors.

[kalvado]

And the real question is why a big and expancive build is chosen when a more simple alternative actually exists. Maybe Wisconsin has budget surplus?

Because there's supposed to be more going into these projects than what can be done today to solve yesterday's problems.  What appears 'simple' via a glance at an aerial picture may have more to it. 

Also, being that the 'Do Nothing' option is the cheapest option, that must mean every state with work going on must have budget surpluses, right?

Most often, the cheapest option isn't going to be the best option because of numerous other factors.

Well, then there is a specific reason NOT to build a roundabout.
Traffic counts on that spot are just shy of 40k/day (I don't quite understand why, but whatever) - and we saw upper limit for roundabout is about 30K. Right turn traffic is low... SO that roundabout would be overcapacity on day 1 - and only grow worse if traffic goes up.
A flyover may be a truly forward-looking solution, but we have money for roundabout only

[jeffandnicole]

Here's a way to view both improvement suggestions without the newspaper site restrictions:

http://wisconsindot.gov/Pages/projects/by-region/nc/us8wis47/default.aspx

[kalvado]

Here's a way to view both improvement suggestions without the newspaper site restrictions:

http://wisconsindot.gov/Pages/projects/by-region/nc/us8wis47/default.aspx

Interesting, that both suggestions remove dedicated high speed right turns - which had some mild flavor of roundaboutness to begin with. Merge issues?

[kphoger]

Here's a way to view both improvement suggestions without the newspaper site restrictions:

http://wisconsindot.gov/Pages/projects/by-region/nc/us8wis47/default.aspx

Interesting, that both suggestions remove dedicated high speed right turns - which had some mild flavor of roundaboutness to begin with. Merge issues?

Thanks for pointing that out.  I wonder if it's because the scope of the project doesn't extend far enough out from the intersection itself to make any merge improvements, therefore the solution was to simply eliminate them.

[kalvado]

Here's a way to view both improvement suggestions without the newspaper site restrictions:

http://wisconsindot.gov/Pages/projects/by-region/nc/us8wis47/default.aspx

Interesting, that both suggestions remove dedicated high speed right turns - which had some mild flavor of roundaboutness to begin with. Merge issues?

Thanks for pointing that out.  I wonder if it's because the scope of the project doesn't extend far enough out from the intersection itself to make any merge improvements, therefore the solution was to simply eliminate them.

Scope of the project has to extend enough to include removal, though. I suspect traffic counts on those didn't quite support the case (~1000 each, I already closed that page)

[kphoger]

Here's a way to view both improvement suggestions without the newspaper site restrictions:

http://wisconsindot.gov/Pages/projects/by-region/nc/us8wis47/default.aspx

Interesting, that both suggestions remove dedicated high speed right turns - which had some mild flavor of roundaboutness to begin with. Merge issues?

Thanks for pointing that out.  I wonder if it's because the scope of the project doesn't extend far enough out from the intersection itself to make any merge improvements, therefore the solution was to simply eliminate them.

Scope of the project has to extend enough to include removal, though. I suspect traffic counts on those didn't quite support the case (~1000 each, I already closed that page)

Right, but scope of project might not include the ability to extend acceleration lanes.

[jakeroot]

They appear to be eliminating the merges to improve pedestrian accommodation. The right turns still appear to be slip lanes with yield signs (judging by the lack of a stop line in the diagram). But, I don't see any crosswalk markings in the intersection, so perhaps its just to cut down on failure-to-yield situations with the current slip lanes. The slip lanes that meet at the angle shown in the diagram have been shown to improve pedestrian safety and reduce collisions.

I would prefer they kept the signalised intersection, with the improved left turns. A really cheap alternative would be to switch the left turns at the current intersection to protected-only, but that would seriously diminish the capacity of the intersection (and judging the current proposal, they already know this since that isn't one of the alternatives).

[tradephoric]

Nobody in misery here.   We enjoy being able to travel without unneeded backups from obsolete traffic lights and 4 way stops.

CJW2001, here's a challenge for you.  Take a video driving 20 miles through the roundabouts of Carmel and let's see how long it takes you.  Here's a 20 mile drive through the traffic lights of Detroit (averaged 46 mph over 20 miles).  Just imagine if every traffic signal in the video was a roundabout and how much longer it would take to drive. 

CJW2001, bump that challenge to 40 miles.  At a minimum every Carmel driver has to slow down as they approach a roundabout.  Often drivers will have to come to a complete stop if vehicles are already circulating through the roundabout.  Talk about needless delays!  Maybe Carmel could have spent a few hundred thousand to retime their traffic lights as opposed to spending a few hundred million to construct all those roundabouts - and after all those roundabouts drivers still experience delays as they have to slow down at every roundabout they approach.  Conversely, you could cruise 40 miles hitting 124 consecutive green lights and barely tap your brakes. 

https://www.youtube.com/watch?v=mb2R2fPB1nE&feature=youtu.be

Meanwhile roundabouts number 111 and 112 are opening in Carmel, with no mass carnage. 

No mass carnage?  There have been 5 documented fatalities over the past decade at Carmel's roundabout. That is fatal carnage.  I've asked you this before but can you cite even one example of a fatal traffic signal crash in Carmel over the past decade?  Considering a decade ago there were more traffic signals than roundabouts in Carmel that should be easy to find.

[jakeroot]

Maybe Carmel could have spent a few hundred thousand to retime their traffic lights as opposed to spending a few hundred million to construct all those roundabouts - and after all those roundabouts drivers still experience delays as they have to slow down at every roundabout they approach.  Conversely, you could cruise 40 miles hitting 124 consecutive green lights and barely tap your brakes.

Yeah good point. All Carmel needs is 180-foot ROW for all their roads, and a diminishing population. Problems solved!