Crash prone 'modern roundabouts'

[jakeroot]

Does anyone know what these markings are called? I've circled them in the satellite image below of the Fairway/Kossuth/Fountain roundabout in Cambridge, ON

I know kphoger and j&n have already filled you in, but they are commonly called "shark's teeth" as well, to distinguish them from the adjacent dashed white lines.

[DaBigE]

Put another way... the IIHS assured us that roundabouts are safer so we can build any roundabout we want... hell we're going to put some boulders in the middle of this one.  No harm will be done when drivers strike them... ooh wait, maybe a driver will hit those rocks, causing their vehicle to flip over and catch on fire, burning the driver alive where they can only be identified through dental records.  Yeah, that could happen too i guess.  Maybe not all roundabouts are created equal and maybe it was a really bad idea to put those boulders in the middle of the central island.

Really? I'm not saying we should be putting boulders in the center of a roundabout, but how are they any different than any other fixed object you find along just about any other road? Utility poles, trees, a building too close to a road...hell, many of the newer monotube traffic signal poles aren't breakaway. And even if you only have a mound of grass, it can still be deadly. Several years ago, there was a motorcyclist who vaulted over the central island and hit a Yield sign on the opposite side. Yeah, you guessed it, alcohol and excessive speed were the causes. I had a friend doing something stupid along a country back-road...going too fast, caught some air on a hill, lost control, and hit a utility pole. Dead on impact. So, by your argument, it's the utility company's fault my friend is dead? (FYI, the pole was outside of the right-of-way). Should everything be designed for every possible outcome of a driver doing something stupid, who accounts for a tiny fraction of the overall motoring public?

This maybe an easier solution...wrap anything and everything in 5 layers of industrial-grade bubble wrap.

[kalvado]

Put another way... the IIHS assured us that roundabouts are safer so we can build any roundabout we want... hell we're going to put some boulders in the middle of this one.  No harm will be done when drivers strike them... ooh wait, maybe a driver will hit those rocks, causing their vehicle to flip over and catch on fire, burning the driver alive where they can only be identified through dental records.  Yeah, that could happen too i guess.  Maybe not all roundabouts are created equal and maybe it was a really bad idea to put those boulders in the middle of the central island.

Really? I'm not saying we should be putting boulders in the center of a roundabout, but how are they any different than any other fixed object you find along just about any other road? Utility poles, trees, a building too close to a road...hell, many of the newer monotube traffic signal poles aren't breakaway. And even if you only have a mound of grass, it can still be deadly. Several years ago, there was a motorcyclist who vaulted over the central island and hit a Yield sign on the opposite side. Yeah, you guessed it, alcohol and excessive speed were the causes. I had a friend doing something stupid along a country back-road...going too fast, caught some air on a hill, lost control, and hit a utility pole. Dead on impact. So, by your argument, it's the utility company's fault my friend is dead? (FYI, the pole was outside of the right-of-way). Should everything be designed for every possible outcome of a driver doing something stupid, who accounts for a tiny fraction of the overall motoring public?

This maybe an easier solution...wrap anything and everything in 5 layers of industrial-grade bubble wrap.

If you will, it is about momentary lapse of attention - what are the consequences? on a straight road without obstacles consequences are usually minimal. Many highways have rumble strips and/or railings along the shoulder to minimize effects. Curbstone along the street also helps to avoid poles. Bright signs at curves and T intersections are there as well.

While running red light is definitely illegal and dangerous - few of this events end up as actual accidents, most limited with swearing, honking and replacement underwear.  Here we're talking about situation, when equivalent of running red light is almost guaranteed to be an injury accident.

[tradephoric]

Welcome back DaBigE.   Haven't seen any posts from you for a while and it's good to hear from you again.  You are just the person I wanted to talk to.  A few posts back a triple-lane teardrop roundabout in Jeffersonville, Indiana was being discussed.  In the first 9 months of operation there were 134 crashes, 9 injury crashes, and 2 semi's that tipped over inside the roundabout.  It hasn't been a great start to say the least.  I know other triple-lane interchange roundabouts have been built and I wonder how they have performed.   Specifically, Green Bay has built 5 triple-lane interchange roundabouts in recent years:

Mason Street & NB Hwy 41 (built 2012)
Mason Street & SB Hwy 41 (built 2012)
Main Ave & Mid Valley Drive/SB Hwy 41 on-ramp (built 2014?)
Shawano Ave & NB Hwy 41 (built 2014)
Shawano Ave & SB Hwy 41 (built 2014)

The Brown County Planning Commission published a detailed Intersection Crash Study in February 2015 but the crash data only goes up to 2012.  So my question is do you know where I can find up to date intersection crash data for the Green Bay Metropolitan Area?  I thought you might know where to find this data since you are the unofficial Wisconsin expert.  Here's the Intersection Crash Study i was able to find:
http://www.co.brown.wi.us/i/f/Metro%20area%20crash%20study%20for%202010-2012%20(final)%20-%20February%202015.pdf

To respond to your previous post, no I don't want to live in bubble-boy world.  The point was I don't see what function those boulders serve.  Was it meant for aesthetics?  It's my personal believe that if the central island was a simple patch of grass that fewer people would be injured at the roundabout.  Sure, you will still have motorcyclists hopping curbs at roundabouts and finding ways to kill themselves.  But that doesn't mean we shouldn't try to get rid of the unnecessary obstacles.  There have already been two fatal crashes at the Hamburg roundabout since it opened in 2011 and the boulders played a part in that.  This is a statement Renee Wall made in a news article about her brother's death. 

"It was not well lit, the speed limit is 45, it goes from two lanes to one. But to put boulders in the middle of it? They're not forgiving."

Renee is absolutely right.  Those boulders in the middle of the roundabout were not forgiving.  It didn't take long for someone to find that out the hard way.

[jeffandnicole]

Renee is absolutely right.  Those boulders in the middle of the roundabout were not forgiving.  It didn’t take long for someone to find that out the hard way.

You never know...there could've been someone traveling on the other side of the roundabout, and the boulder saved the idiot driver from plowing thru the median into their car, killing them instead.

[tradephoric]

You never know...there could've been someone traveling on the other side of the roundabout, and the boulder saved the idiot driver from plowing thru the median into their car, killing them instead.

Actually, we know the facts of this case... no need to play hypotheticals.  Investigators believe "Braun was heading north on South Park Avenue when his pickup truck collided with decorative boulders in the middle of the roundabout and flipped in the air, landing in the southbound lane" .

http://hamburg.wgrz.com/news/news/60422-victim-identified-hamburg-fatal-crash

The vehicle wasn't contained in the central island after striking the boulders.  It cleared the boulders and landed upside down in the southbound lanes.  In the future try reading the articles i post as it might fill you in on some facts.

[jeffandnicole]

It cleared the boulders and landed upside down in the southbound lanes.  In the future try reading the articles i post as it might fill you in on some facts.

I read the article, and it failed to tell me the other traffic that was in the roundabout; it just told me about this car, that it cleared the boulders, and eventually landed in the southbound lanes.  Please include all the details regarding everything within the roundabout at the time so I know all the facts.

Oh, wait...

"...no need to play hypotheticals.  Investigators believe"

Please...reread that about a hundred times, and tell me how "believe" is not the same as "hypothetical".   Thus, even what you read states that they don't know the facts...they can only draw up a reasonable conclusion.

[tradephoric]

^There is a picture of the pickup upside down in the southbound lane of the roundabout.  That picture isn't a cartoon.  Your assumption was that the boulders would stop a driver from blowing straight through the roundabout.  All your semantics doesn't change the fact that your assumption was wrong. 

[tradephoric]

Here are two similar capacity triple-lane interchange roundabouts.  One is the Jeffersonville, Indiana roundabout that has been a trouble spot over the first 9 months (134 crashes, 9 injuries, and 2 semi's tipped over).  The other roundabout is from Green Bay constructed in 2014.  I haven't read any articles to suggest that this Green Bay roundabout is a hot spot for crashes but I don't have any crash data to verify this either.  Does one design look superior to the other?

10th Street & EB 265; Jeffersonville, Indiana 


Shawano Ave & NB US 41; Green Bay, Wisconsin

[DaBigE]

So my previous comment was based solely on the discussion here and the little the news story had about the crash. I was originally envisioning something with more buffer space between the rocks and the roadway. Looking at the intersection in Google Earth (this is the one, correct?), this roundabout was an accident waiting to happen. From my perspective, there is no way that central island landscaping should have been allowed, especially with that design and those approach speeds. While it does have a barrier curb separating the truck apron from the decoration, there's maybe a foot of space from the curb head to the rock. We require at least 6-feet of distance from the final barrier curb to any landscaping in the central island (mainly for sight, but it also can act as a small recovery zone). Not knowing what kind of trucks have to get through there, I'd say the apron is over-sized for the needs of a standard semi. That would have potentially allowed for a more-forgiving central island design. While I do see some deflection in the approaches, it seems weak, especially if someone is hugging the fog line.

"It was not well lit, the speed limit is 45, it goes from two lanes to one. But to put boulders in the middle of it? They're not forgiving."

Not well-lit? Without seeing photometrics, I can't say for sure, but I do know I've seen unlit roundabouts with faster approaches and no crash issues. This one appears to have average lighting, based on the poles I see in the GE image. Maybe some lights weren't functioning for whatever reason. What I am not seeing is the "two lanes to one". I do see a TWLTL, but that shouldn't matter, as it's not a legal thru driving lane. It's an otherwise two-lane highway.

[DaBigE]

Here are two similar capacity triple-lane interchange roundabouts.  One is the Jeffersonville, Indiana roundabout that has been a trouble spot over the first 9 months (134 crashes, 9 injuries, and 2 semi's tipped over).  The other roundabout is from Green Bay constructed in 2014.  I haven't read any articles to suggest that this Green Bay roundabout is a hot spot for crashes but I don't have any crash data to verify this either.  Does one design look superior to the other?

Home-state biases aside, the Green Bay one is more superior. The Indiana one has the speed control at the wrong point on the approach, especially for the EB approach. The tangent section between the yielding point and the approach curve allows traffic to speed up as they're entering the roundabout (what we refer to as a "hockey stick" design). There's also an exceptionally large "flat spot"/tangent in the NB circulatory spiral that would encourage more speed.

[tradephoric]

Looking at the intersection in Google Earth (this is the one, correct?), this roundabout was an accident waiting to happen.

Yes, that's the roundabout in question.

Not well-lit? Without seeing photometrics, I can't say for sure, but I do know I've seen unlit roundabouts with faster approaches and no crash issues. This one appears to have average lighting, based on the poles I see in the GE image. Maybe some lights weren't functioning for whatever reason. What I am not seeing is the "two lanes to one". I do see a TWLTL, but that shouldn't matter, as it's not a legal thru driving lane. It's an otherwise two-lane highway.

The fatal crash occurred shortly after the roundabout opened.  There were questions whether or not the roundabout was ready to be opened to traffic in the first place.  According to another article, the night of the fatal crash overhead lights were not in place and the pavement markings had not been completed.  A few weeks after the fatal crash, crews removed the boulders and replaced them with fiberglass rocks designed to buckle when a vehicle passes over them.  The city must really like the aesthetics of the boulders to reinstall fiberglass rocks to get the same look as before.  Why they like that look so much is beyond me.

[tradephoric]

Home-state biases aside, the Green Bay one is more superior. The Indiana one has the speed control at the wrong point on the approach, especially for the EB approach. The tangent section between the yielding point and the approach curve allows traffic to speed up as they're entering the roundabout (what we refer to as a "hockey stick" design). There's also an exceptionally large "flat spot"/tangent in the NB circulatory spiral that would encourage more speed.

Another obvious difference between the two is that the Green Bay roundabout is a dumbbell whereas the Jeffersonville one is a teardrop. I personally favor dumbbells because you never know when someone may want to make a U-turn.  But more importantly, with a dumbbell drivers that are coming from the bridge have to yield to vehicles that may be circulating the roundabout.  Drivers at teardrop roundabouts OTOH don't encounter a yield sign along one of the legs which may make the roundabout feel like more of a racetrack to these drivers.  If they don't see a YIELD sign they may be encouraged to go faster.  I hope what I'm saying makes sense since I think it's an important point.

[DaBigE]

Another obvious difference between the two is that the Green Bay roundabout is a dumbbell whereas the Jeffersonville one is a teardrop. I personally favor dumbbells because you never know when someone may want to make a U-turn.  But more importantly, with a dumbbell drivers that are coming from the bridge have to yield to vehicles that may be circulating the roundabout.  Drivers at teardrop roundabouts OTOH don't encounter a yield sign along one of the legs which may make the roundabout feel like more of a racetrack to these drivers.  If they don't see a YIELD sign they may be encouraged to go faster.  I hope what I'm saying makes sense since I think it's an important point.

Both dumbbell and teardrop roundabout designs have their merits, which is why I left that out of my commentary not having looked in-depth on the context of the locations beyond what your images show. Teardrop, IMO, are better-suited for closely-spaced roundabouts/ramp terminals. Snowplowing benefits could go either way.

[DaBigE]

The fatal crash occurred shortly after the roundabout opened.  There were questions whether or not the roundabout was ready to be opened to traffic in the first place.  According to another article, the night of the fatal crash overhead lights were not in place and the pavement markings had not been completed.  A few weeks after the fatal crash, crews removed the boulders and replaced them with fiberglass rocks designed to buckle when a vehicle passes over them.  The city must really like the aesthetics of the boulders to reinstall fiberglass rocks to get the same look as before.  Why they like that look so much is beyond me.

I would also question if it was ready to be opened as well, however, pavement markings for a single-lane roundabout shouldn't be that critical. Lighting depends on who you ask, as there are quite a few unlit rural roundabouts with no crash issues.

The city probably likes the rocks because they don't require much maintenance...in theory.

[tradephoric]

Both dumbbell and teardrop roundabout designs have their merits, which is why I left that out of my commentary not having looked in-depth on the context of the locations beyond what your images show. Teardrop, IMO, are better-suited for closely space roundabouts/ramp terminals. Snowplowing benefits could go either way.

This dumbbell vs. teardrop (dogbone) roundabout debate has come up before on here.  It's funny because i think it's bad that drivers aren't displayed a yield sign along one of the legs of a teardrop roundabout.  Of course someone on the other thread made a point exactly opposite of me lol

With the dumbbell style, since there are so few vehicles making that U-turn, drivers will get used to never seeing vehicles there and potentially ignore the yield sign.  This becomes a safety hazard, and makes the dogbone style a better choice.  As stated before, drivers can still make that U-turn; they just have to travel a bit farther to do it.
https://www.aaroads.com/forum/?topic=16468.0

[lordsutch]

"I'd say in the past ten years, you've seen an increase in modern roundabouts just because research has proven that they are safer, so we have started implementing them in New York State," said Surdej.  "And we have started implementing them successfully, we are seeing a reduction in accident rates in those intersections where there are modern roundabouts."


http://hamburg.wgrz.com/news/news/60422-victim-identified-hamburg-fatal-crash

Put another way... the IIHS assured us that roundabouts are safer so we can build any roundabout we want... hell we're going to put some boulders in the middle of this one.  No harm will be done when drivers strike them... ooh wait, maybe a driver will hit those rocks, causing their vehicle to flip over and catch on fire, burning the driver alive where they can only be identified through dental records.  Yeah, that could happen too i guess.  Maybe not all roundabouts are created equal and maybe it was a really bad idea to put those boulders in the middle of the central island.

Yes, clearly the NYSDOT spokesperson really hates motorists and wants them to tie horribly in fires. That's the obvious conclusion from the bland quotation that shows no evidence it was actually a response to a question about this specific accident instead of a question like "Why is NYSDOT building roundabouts?"

[DaBigE]

A few posts back a triple-lane teardrop roundabout in Jeffersonville, Indiana was being discussed.  In the first 9 months of operation there were 134 crashes, 9 injury crashes, and 2 semi's that tipped over inside the roundabout.  It hasn't been a great start to say the least.  I know other triple-lane interchange roundabouts have been built and I wonder how they have performed.   Specifically, Green Bay has built 5 triple-lane interchange roundabouts in recent years:

Mason Street & NB Hwy 41 (built 2012)
Mason Street & SB Hwy 41 (built 2012)
Main Ave & Mid Valley Drive/SB Hwy 41 on-ramp (built 2014?)
Shawano Ave & NB Hwy 41 (built 2014)
Shawano Ave & SB Hwy 41 (built 2014)

The Brown County Planning Commission published a detailed Intersection Crash Study in February 2015 but the crash data only goes up to 2012.  So my question is do you know where I can find up to date intersection crash data for the Green Bay Metropolitan Area?  I thought you might know where to find this data since you are the unofficial Wisconsin expert.  Here's the Intersection Crash Study i was able to find:
http://www.co.brown.wi.us/i/f/Metro%20area%20crash%20study%20for%202010-2012%20(final)%20-%20February%202015.pdf

I don't have any other data for you...not in a convenient report form and not without going through quite a bit of bureaucracy that I don't have time for at the moment.  Best bet would be to contact Brown County or WisDOT NE regional office directly. Even if there was easily accessible data, it would be skewed with the various detour routes going through the region, altering the flows the roundabouts were originally designed for. You won't get any reliable after data until the whole project is wrapped-up and all detour routes removed.

All I can say is that the media has been very quiet from that area of the state in regards to those intersections.

[tradephoric]

^Thanks for the info.   Hopefully the numbers will come out soon.  There aren't that many triple lane roundabouts in America and the engineering community would be pretty interested to see how these Green Bay roundabouts are performing.  I wouldn't be surprised if they discuss these roundabouts in detail at the next roundabout conference.  And you make a good point about the detour routes skewing the data.  Of course, roundabouts will be the site of detour routes moving forward since every construction season there are new detour routes.  If roundabouts are designed for a certain traffic pattern and they can't adapt to changing traffic patterns due to detours, that could be a concern.

[johndoe]

The tangent section between the yielding point and the approach curve allows traffic to speed up as they're entering

Perhaps they were more concerned with entry path overlap?  Maybe there is a high percentage of trucks?  Does Wisconsin not encourage the 20' tangent before eoct?

[tradephoric]

Half of Pennsylvania's Roundabouts Show A Decrease In Crashes
http://wnep.com/2016/08/02/half-of-pennsylvanias-roundabouts-show-a-decrease-in-crashes/

I'll be the first to admit I'm no genius, but if half of the roundabouts in Pennsylvania show a decrease in crashes, that means the other half of roundabouts in Pennsylvania either stayed the same or crashes went up.  Pennsylvania hasn't really built any significant roundabouts to date but thought I'd share this news story anyways.  But yeah, flip a coin to determine if a particular roundabout in PA has seen crashes increase or decrease. 

[tradephoric]

Yet another 2x2 multi-lane roundabout has been downsized and this time it's in Carmel.  The roundabout at 116th & Illinois has historically been a high crash intersection in the city.  The EB right lane on 116th has been re-striped as a right turn only lane. 

They are downsizing one crash prone 2x2 multi-lane roundabout in Carmel only to construct another 2x2 multi-lane roundabout at Carmel Drive & Rangeline Road (scheduled to be complete this November).  Over the next few years that roundabout will probably make the city's high crash intersection list and they will have to contemplate downsizing it in the future.  Every time i update this chart it's getting more and more yellow (indicating roundabouts that have had circulating lanes removed):

[DaBigE]

The tangent section between the yielding point and the approach curve allows traffic to speed up as they're entering

Perhaps they were more concerned with entry path overlap?  Maybe there is a high percentage of trucks?  Does Wisconsin not encourage the 20' tangent before eoct?

You can prevent entry path overlap without having the tangent occur that far down the entry. Since a picture = 1K words, see Figure 30.17 (pg 63) for Wisconsin's design guidance. Similarly, there are other ways of dealing with higher percentages of trucks, like striping out a gore between the entry lanes. Or, ban vehicles from traveling adjacent to trucks near/within roundabouts as one of Wisconsin's newer laws does.

[lordsutch]

Half of Pennsylvania's Roundabouts Show A Decrease In Crashes
http://wnep.com/2016/08/02/half-of-pennsylvanias-roundabouts-show-a-decrease-in-crashes/

I'll be the first to admit I'm no genius, but if half of the roundabouts in Pennsylvania show a decrease in crashes, that means the other half of roundabouts in Pennsylvania either stayed the same or crashes went up.  Pennsylvania hasn't really built any significant roundabouts to date but thought I'd share this news story anyways.  But yeah, flip a coin to determine if a particular roundabout in PA has seen crashes increase or decrease.

Half of... ten.

[jakeroot]

Every time i update this chart it's getting more and more yellow (indicating roundabouts that have had circulating lanes removed):

You can highlight the Steptoe Roundabout in Washington. Circulating lanes were removed from two approaches in mid-July.