Crash prone 'modern roundabouts'

[lordsutch]

If you replace virtually all of the major intersections in a city with one of a particular type, virtually by definition nearly all of the deaths are going to be at that type of intersection, since people typically don't crash their cars in locations that aren't intersections (unless they fall asleep/have a heart attack at the wheel and run off the road).

Hence of course people are going to die in accidents in Carmel at roundabouts because there's almost no other type of intersection being used for major intersections in the city. If Carmel ripped them all out tomorrow and replaced them with all-way stops... all the deaths would now be at all-way stops (statistically there'd also be a lot more of them, although PDO crashes might go down).

[tradephoric]

Hence of course people are going to die in accidents in Carmel at roundabouts because there's almost no other type of intersection being used for major intersections in the city.

A lot of traffic signals and 4-way stops exist in Carmel, Indiana.  Here is a map that shows the current breakdown of traffic signals, roundabouts, and all-way stops:


Green dots = roundabouts
Yellow dots = all-way stops
Red dots = traffic signals

As you can see, there is an even mix of roundabouts and non-roundabout intersections in the city.  The fact is there were 3 fatal crashes at Carmel's roundabouts over a 27 month period (January 2014-March 2016).  Compare that to just one fatal crash at Carmel's traffic signals and all-way stops during the same time period.  Carmel is the self-proclaimed roundabout capital of the country but it hasn't had a good track record of preventing fatal crashes.  You have been better off driving through those "dangerous"  red dots.

[cjw2001]

I drive in this area every day, and I feel far safer in the roundabouts then at the traffic signals and four way stops.  Looking forward to the addition of 30 more.

I find it amusing that someone from outside the area needs to tell me how I'm in so much danger.

[tradephoric]

^ I find it amusing that you think your personal anecdotal evidence means anything.  It doesn't change the facts.  National studies have suggested that roundabouts reduce fatal crashes by 90% yet Carmel has had triple the number of fatal crashes at their roundabouts than their signalized intersections over a 27 month period.  Go ahead and dispute that, but come back with some meaningful facts and not just anecdotal BS.

[cjw2001]

^ I find it amusing that you think your personal anecdotal evidence means anything.  It doesn't change the facts.  National studies have suggested that roundabouts reduce fatal crashes by 90% yet Carmel has had triple the number of fatal crashes at their roundabouts than their signalized intersections over a 27 month period.  Go ahead and dispute that, but come back with some meaningful facts and not just anecdotal BS.

I understand that you hate roundabouts, but that's no reason to go into name calling.  My personal experience is not BS.  I drive these roads every day.   Feel free to disagree, but don't call other people's posts BS.

[silverback1065]

Hence of course people are going to die in accidents in Carmel at roundabouts because there's almost no other type of intersection being used for major intersections in the city.

A lot of traffic signals and 4-way stops exist in Carmel, Indiana.  Here is a map that shows the current breakdown of traffic signals, roundabouts, and all-way stops:


Green dots = roundabouts
Yellow dots = all-way stops
Red dots = traffic signals

As you can see, there is an even mix of roundabouts and non-roundabout intersections in the city.  The fact is there were 3 fatal crashes at Carmel's roundabouts over a 27 month period (January 2014-March 2016).  Compare that to just one fatal crash at Carmel's traffic signals and all-way stops during the same time period.  Carmel is the self-proclaimed roundabout capital of the country but it hasn't had a good track record of preventing fatal crashes.  You have been better off driving through those "dangerous"  red dots.

In a city with over 100 roundabouts, having only 3 fatal crashes in over 2 years actually disproves your point completely.  I live in Carmel too, and it is much safer, and traffic moves much better.  Also why didn't you look at the stats when there were much more signals in the city?  How about when US 31 was completely signaled?  Not to mention the many accidents that occur at 96th and keystone, a signal.  The remaining signals in Carmel are all at not very busy intersections, so accidents wouldn't happen frequently.  Also, one of the 3 was a drunk driver who tried to drive straight through one.  2 of the red dots aren't even in carmel, they're in another community called Home Place that the county maintains.

[tradephoric]

Not to mention the many accidents that occur at 96th and Keystone, a signal.

According to the Carmel Police Department's 2014 Annual report the intersection of 96th & Keystone ranked in the top 20 highest crash locations with 38 total crashes.  But the roundabout at 116th & Keystone had even more with 68 total crashes.  Keep in mind all the through traffic on Keystone bypasses the 116th & Keystone roundabout so you would think it would experience much lower traffic volumes than the at-grade signalized intersection of 96th & Keystone.  The roundabout at 116th & Keystone had 78% more crashes than the traffic signal at 96th & Keystone yet you only want to point out the high number of crashes happening at the traffic signal.  Why are you ignoring the high crash roundabouts in your city?

You also mentioned that people were drinking in some of the fatal roundabout crashes that occurred over the past few years.  Ok.  What's your point?  The national studies don't omit fatal crashes just because someone was drunk.  According to the national studies, they cite roundabouts should lead to a significant reduction in fatal crashes.  We aren't seeing a reduction in fatalities in Carmel.  There are plenty of high volume signalized intersections remaining in Carmel, yet over the past few years the majority of fatal crashes in Carmel have happened at roundabouts.  It's not what you would expect in the roundabout capital of America.

[silverback1065]

Not to mention the many accidents that occur at 96th and Keystone, a signal.

According to the Carmel Police Department's 2014 Annual report the intersection of 96th & Keystone ranked in the top 20 highest crash locations with 38 total crashes.  But the roundabout at 116th & Keystone had even more with 68 total crashes.  Keep in mind all the through traffic on Keystone bypasses the 116th & Keystone roundabout so you would think it would experience much lower traffic volumes than the at-grade signalized intersection of 96th & Keystone.  The roundabout at 116th & Keystone had 78% more crashes than the traffic signal at 96th & Keystone yet you only want to point out the high number of crashes happening at the traffic signal.  Why are you ignoring the high crash roundabouts in your city?

You also mentioned that people were drinking in some of the fatal roundabout crashes that occurred over the past few years.  Ok.  What's your point?  The national studies don't omit fatal crashes just because someone was drunk.  According to the national studies, they cite roundabouts should lead to a significant reduction in fatal crashes.  We aren't seeing a reduction in fatalities in Carmel.  There are plenty of high volume signalized intersections remaining in Carmel, yet over the past few years the majority of fatal crashes in Carmel have happened at roundabouts.  It's not what you would expect in the roundabout capital of America.

It's exactly what you would expect in a city where the primary feature is a roundabout. What's your point?
You are basically trying to say roundabouts should have no crashes. Signals have many safety issues that are well documented. You also don't even account traffic volume in your analysis.
You could put the same analysis with Indianapolis comparing it's many signals to the small amount of roundabouts and come to the opposite conclusion.
I'd also like to see before and after analysis to see if the signal had more or less crashes than the roundabout.

[silverback1065]

Honestly, Jim Brainard has kind of lost his mind when it comes to roundabouts, there are some in the city that honestly don't need to be there at all, or the signal was fine. I feel he's more concerned about traffic flow than accidents.

[kalvado]

In a city with over 100 roundabouts, having only 3 fatal crashes in over 2 years actually disproves your point completely.  I live in Carmel too, and it is much safer, and traffic moves much better.  Also why didn't you look at the stats when there were much more signals in the city?  How about when US 31 was completely signaled?  Not to mention the many accidents that occur at 96th and keystone, a signal.  The remaining signals in Carmel are all at not very busy intersections, so accidents wouldn't happen frequently.  Also, one of the 3 was a drunk driver who tried to drive straight through one.  2 of the red dots aren't even in carmel, they're in another community called Home Place that the county maintains.

Honestly speaking, feeling safer has very little to do with actual safety. And they don't care about your beliefs in intensive care unit.

You are basically trying to say roundabouts should have no crashes. Signals have many safety issues that are well documented. You also don't even account traffic volume in your analysis.

Traffic lights problems may be well documented - but main problem of roundabouts is lack of understanding. Unfortunately, my strong impression is that US has few qualified traffic engineers left.
There were some people in Ireland trying to perform in-depth analysis of roundabouts. If you look at their publications, it is pretty clear where roundabouts actually belong and where they don't. But those publications seem way beyond comprehension level of those in charge.

[silverback1065]

One of the bigger problems is that a lot of times, they're just a rubber stamp for what the mayor wants. And this is definitely true of Carmel. Even if they disagree with the mayor, they'll get overruled.

Nexus 6P

[jeffandnicole]

Unfortunately, my strong impression is that US has few qualified traffic engineers left.

This statement would be a candidate for the most grossly inaccurate statement of the year.

Unless the roads you're driving on are collapsing on a daily basis, a traffic engineer created or signed off on that design that's keeping you safe.

If people can't negotiate roundabouts, that doesn't mean a traffic engineer messed up. It means the motorist messed up.

[kalvado]

Unfortunately, my strong impression is that US has few qualified traffic engineers left.

This statement would be a candidate for the most grossly inaccurate statement of the year.

Unless the roads you're driving on are collapsing on a daily basis, a traffic engineer created or signed off on that design that's keeping you safe.

If people can't negotiate roundabouts, that doesn't mean a traffic engineer messed up. It means the motorist messed up.

There is structural engineering, and there is traffic engineering. I sure hope that the guy who designed the concrete of the bridge is not the one who designed stripping on it - you know, I cannot afford a helicopter...
Alternatively, if it is indeed same guy, I would pray that he knows structural things. As for stripping.. Well, bridge wouldn't collapse because of stripping....

[jeffandnicole]

Unfortunately, my strong impression is that US has few qualified traffic engineers left.

This statement would be a candidate for the most grossly inaccurate statement of the year.

Unless the roads you're driving on are collapsing on a daily basis, a traffic engineer created or signed off on that design that's keeping you safe.

If people can't negotiate roundabouts, that doesn't mean a traffic engineer messed up. It means the motorist messed up.

There is structural engineering, and there is traffic engineering. I sure hope that the guy who designed the concrete of the bridge is not the one who designed stripping on it - you know, I cannot afford a helicopter...
Alternatively, if it is indeed same guy, I would pray that he knows structural things. As for stripping.. Well, bridge wouldn't collapse because of stripping....

Put the stripping too close to the outer edge of the bridge, where the bridge height may fall under 13' 6", and have a truck come along...

[kalvado]

Unfortunately, my strong impression is that US has few qualified traffic engineers left.

This statement would be a candidate for the most grossly inaccurate statement of the year.

Unless the roads you're driving on are collapsing on a daily basis, a traffic engineer created or signed off on that design that's keeping you safe.

If people can't negotiate roundabouts, that doesn't mean a traffic engineer messed up. It means the motorist messed up.

There is structural engineering, and there is traffic engineering. I sure hope that the guy who designed the concrete of the bridge is not the one who designed stripping on it - you know, I cannot afford a helicopter...
Alternatively, if it is indeed same guy, I would pray that he knows structural things. As for stripping.. Well, bridge wouldn't collapse because of stripping....

Put the stripping too close to the outer edge of the bridge, where the bridge height may fall under 13' 6", and have a truck come along...

Oh, OK.. Looks like I have to start saving for a helicopter...

[silverback1065]

Striping and signage isn't the problem, driver fuck ups are, hard to negotiate a roundabout when your texting or pokemon going.  I still see people trying to make a left turn in a roundabout (the wrong way) there is obvious signage, striping, fuck the damn median forces you to go right.  I think another problem is people incorrectly assuming where people in the roundabout are going and causing crashes, since you cannot signal in a roundabout, you have to wait.

[silverback1065]

Unfortunately, my strong impression is that US has few qualified traffic engineers left.

This statement would be a candidate for the most grossly inaccurate statement of the year.

Unless the roads you're driving on are collapsing on a daily basis, a traffic engineer created or signed off on that design that's keeping you safe.

If people can't negotiate roundabouts, that doesn't mean a traffic engineer messed up. It means the motorist messed up.

I agree that statement is bullshit

[jakeroot]

Here on the west coast, some of the engineering schools are exceptionally difficult to get into, due to the recent influx of students from China. These students are exceptionally good at math, and present stiff competition when applying for an engineering program.

My point being, only the very best of the best are getting into engineering programs (at least out here).

[kalvado]

Here on the west coast, some of the engineering schools are exceptionally difficult to get into, due to the recent influx of students from China. These students are exceptionally good at math, and present stiff competition when applying for an engineering program.

My point being, only the very best of the best are getting into engineering programs (at least out here).

Best of best are applying for medical and MBA programs. That's where money is. 
And in any case, most roads we have today were designed 15 years ago and build 10 years ago by those who graduated  20-25 years ago and now think about retirement.  That is optimistic  scenario - average bridge age in US is 50 years, you know..

[tradephoric]

Yet another 3x2 crash prone roundabout has been downsized to a 2x2 roundabout.  The roundabout at 14 Mile & Farmington in West Bloomfield, Michigan was recently restriped to only include two circulating lanes through the roundabout.  According to MDOT, there were 36.43 average crashes before the roundabout was built and 67.33 average crashes after the roundabout (http://www.michigan.gov/documents/mdot/MDOT_Research_Report_RC1566_379286_7.pdf).  This follows the downsizing of other 3x2 roundabouts in the area including the one at Maple & Farmington and Maple & Drake. 

The remaining 3x2 roundabout in the area is the one at Pontiac Trail & M-5 (which was originally constructed in 2011).  The Pontiac Trail & M-5 roundabout was the highest crash prone intersection in the entire state of Michigan for 2015 with 186 total crashes (the intersection of 12 Mile & Telegraph ranked second with 132 crashes).
http://www.freep.com/story/news/local/michigan/oakland/2016/06/05/oakland-county-most-dangerous-intersection-state/85305668/

[JCinSummerfield]

Here in Toledo, OH, the intersection of Cherry, Berdan & Detroit Streets has been a roundabout for several months now.  Accidents occur daily.  What nobody has figured out is that the signage and the pavement striping don't match - at least entering from Cherry St.  I've also seen people make the wrong move for the lane they are in, so it's a combination of engineering issues and driver issues.

[tradephoric]

Here in Toledo, OH, the intersection of Cherry, Berdan & Detroit Streets has been a roundabout for several months now.  Accidents occur daily.  What nobody has figured out is that the signage and the pavement striping don't match - at least entering from Cherry St.  I've also seen people make the wrong move for the lane they are in, so it's a combination of engineering issues and driver issues.

Wow, you're not kidding.  A lot of people traveling on Cherry Street would assume that continuing on Detroit Avenue is the "straight"  movement while continuing onto Berdan Avenue would be the "turn" movement.  The pavement markings direct vehicles who entered the roundabout from the left lane to continue straight onto Detroit Avenue (and conversely, right lane traffic who enters the roundabout have to cross a solid white line to continue onto Berdan Ave).  I definitely could see myself getting confused driving this roundabout and i should know better.  I'm sure in the next few posts someone with a PHD in roundabout design will explain why the pavement markings and signage is correct, without considering how confusing it is to the average Joe.



The most likely scenario is in a few years time, they will make the right most lane a right turn only lane and convert it to a 2x1 roundabout to limit confusion (and to alleviate the high crash rate).

[jakeroot]

Here in Toledo, OH, the intersection of Cherry, Berdan & Detroit Streets has been a roundabout for several months now.  Accidents occur daily.  What nobody has figured out is that the signage and the pavement striping don't match - at least entering from Cherry St.  I've also seen people make the wrong move for the lane they are in, so it's a combination of engineering issues and driver issues.

Wow, you're not kidding.  A lot of people traveling on Cherry Street would assume that continuing on Detroit Avenue is the "straight"  movement while continuing onto Berdan Avenue would be the "turn" movement.  The pavement markings direct vehicles who entered the roundabout from the left lane to continue straight onto Detroit Avenue (and conversely, right lane traffic who enters the roundabout have to cross a solid white line to continue onto Berdan Ave).  I definitely could see myself getting confused driving this roundabout and i should know better.  I'm sure in the next few posts someone with a PHD in roundabout design will explain why the pavement markings and signage is correct, without considering how confusing it is to the average Joe.

http://i478.photobucket.com/albums/rr144/tradephoric/Transportation%20Pictures/Roundabouts/Toledocon_zpsdfrdsnw7.png

This is why, under certain circumstances, I prefer no lane markings to confusing lane markings. If this roundabout didn't have any lane markings, traffic may be able to better interpret the through movement, but the way it's setup, through traffic has no chance: the movement becomes less of a straight-on movement, and more of a "merge then slight left", all because of the solid lane line.

[7/8]

Here in Toledo, OH, the intersection of Cherry, Berdan & Detroit Streets has been a roundabout for several months now.  Accidents occur daily.  What nobody has figured out is that the signage and the pavement striping don't match - at least entering from Cherry St.  I've also seen people make the wrong move for the lane they are in, so it's a combination of engineering issues and driver issues.

Wow, you're not kidding.  A lot of people traveling on Cherry Street would assume that continuing on Detroit Avenue is the "straight"  movement while continuing onto Berdan Avenue would be the "turn" movement.  The pavement markings direct vehicles who entered the roundabout from the left lane to continue straight onto Detroit Avenue (and conversely, right lane traffic who enters the roundabout have to cross a solid white line to continue onto Berdan Ave).  I definitely could see myself getting confused driving this roundabout and i should know better.  I'm sure in the next few posts someone with a PHD in roundabout design will explain why the pavement markings and signage is correct, without considering how confusing it is to the average Joe.

I'm struggling to see how someone could defend this, it just seems wrong to me!

The most likely scenario is in a few years time, they will make the right most lane a right turn only lane and convert it to a 2x1 roundabout to limit confusion (and to alleviate the high crash rate).

This would be the easiest way to solve the problem, and at least you wouldn't have to change that stripe in the roundabout.

Ideally, they should have had Cherry St bend to the west before the roundabout to prevent the confusion about Detroit St being a "right turn". But maybe they didn't have the ROW?

[kalvado]

I'm struggling to see how someone could defend this, it just seems wrong to me!

Pretty obvious, if you zoom out, you can clearly see which road goes through and which is turning.
And if average Joe is so stupid that he cannot see the big picture while driving through, that is not engineer's problem!

However, honestly speaking, pre-roundabout layout which still shows on web maps, is not much better. I have hard time thinking of a good layout - really no straightforward solution, and local traffic pattern has to be taken into account. And overall area looks... messy. With lots of homes, lots of commute, and lots of NIMBYs....