Crash prone 'modern roundabouts'

[kalvado]

Seriously Tim?  One crash per 127,000 vehicles equates to a crash rate of 7.87 MEV.  That isn't considered "quite low"  in the engineering community.  In fact, a crash rate of 7.87 MEV is nearly 10x higher than the crash rate of a typical signalized intersection.  Either Tim Burkman is a complete moron who got his degree from the back of a cracker-jack box or he's lying to the people of Valparaiso.

Indoctrination. Roundabouts are best thing since sliced bread. All the facts support that, and if facts seem to contradict - see above.
I think we'll see statements like "only 5 people died on that intersection in a past year" as circles keep spreading - and yes, that is indeed "only 5" when compared with, for example, murder rate in Chicago.

[tradephoric]

You won't have to worry about comparing roundabouts to the traffic signals in Carmel much longer.   Most of the remaining traffic signals are on their way out.

The general consensus is that roundabouts are safer than signalized intersections.  I agree with that consensus since the majority of roundabouts in the country are either single lane or simplified multi-lane roundabouts (and Carmel is no exception).  But in recent years more and more 2x2 and 2x3 configurations have been built and there's growing evidence that these roundabouts aren't safer.  They have significantly higher crash rates than standard signalized intersections and there are several examples where even total injury crash rates are higher.

When looking at the map in the link you provided, the roundabouts being proposed in Carmel are concentrated in the middle of the city along major 4-lane roads (ie. 116th Street, Range Line Road, Carmel Drive).   Presumably many of these roundabouts will need to have 2x2 configurations to handle the high traffic volumes and perhaps Carmel will even get into the triple roundabout game.  Let's face it, Carmel has constructed some pretty mundane roundabouts — sure they have built a lot of them — but they are basic.   Crashes at Carmel roundabouts have nowhere to go but up since the city is transitioning towards building more 2x2 configurations (and perhaps even some 2x3's).  You really think Carmel is immune from high crash rate roundabouts?  Get ready for a future headline "Rangeline Road and Carmel Drive roundabout has most crashes in Hamilton County" . 

[silverback1065]

You won't have to worry about comparing roundabouts to the traffic signals in Carmel much longer.   Most of the remaining traffic signals are on their way out.

The general consensus is that roundabouts are safer than signalized intersections.  I agree with that consensus since the majority of roundabouts in the country are either single lane or simplified multi-lane roundabouts (and Carmel is no exception).  But in recent years more and more 2x2 and 2x3 configurations have been built and there's growing evidence that these roundabouts aren't safer.  They have significantly higher crash rates than standard signalized intersections and there are several examples where even total injury crash rates are higher.

When looking at the map in the link you provided, the roundabouts being proposed in Carmel are concentrated in the middle of the city along major 4-lane roads (ie. 116th Street, Range Line Road, Carmel Drive).   Presumably many of these roundabouts will need to have 2x2 configurations to handle the high traffic volumes and perhaps Carmel will even get into the triple roundabout game.  Let's face it, Carmel has constructed some pretty mundane roundabouts — sure they have built a lot of them — but they are basic.   Crashes at Carmel roundabouts have nowhere to go but up since the city is transitioning towards building more 2x2 configurations (and perhaps even some 2x3's).  You really think Carmel is immune from high crash rate roundabouts?  Get ready for a future headline "Rangeline Road and Carmel Drive roundabout has most crashes in Hamilton County" .

When it is all said and done, Carmel will have a total of 5 Signals. One at Main and Rangeline, and 4 along US 421.  421's will never go away unless INDOT wants them to, 2 of these signals will never go away as they are shopping center signals.  I am against the Carmel/Rangeline roundabout, I'm not convinced it will make traffic better.  22,000 cars a day go through that intersection, and there are plans to make rangeline a 2 lane road, which will actually make traffic worse.  Almost none of these decisions are being made by engineers, they're all coming from a mayor who is obsessed. 

[silverback1065]

there are 32 more being built in the next 5 yrs by the way.  My biggest problem with Brainard (the mayor of carmel) is that he incorrectly assumes that the roundabout is the silver bullet to solve ALL intersections, this is simply not true!  There are a few questionable areas all around the city that either a roundabout didn't need to be there at all, or it actually made things worse (from a traffic flow perspective). 

[lordsutch]

Since your one prediction was wrong let's shift focus to injury crashes and death.  It's almost as if in your own mind you never suggested that the Dublin roundabout would reduce crash frequency, even though you did.  Anyways, on September 5th the Dublin Police department reported an injury motorcycle crash at the new roundabout.  It wouldn't shock me if the Dublin roundabout averaged an injury crash per month over the next year.  As I recall the Jeffersonville, Indiana roundabout had 9 injury crashes in the first 10 months of operation.  Both the Dublin and Jeffersonville roundabouts are confusing triple-lane clusters of fun and could end up with similar injury crashes.  I wouldn't bet against it.  Before you take that bet lodrsutch, just remember it only took you 20 days to be wrong about the frequency of crashes.

I'll gladly accept a wager that in two year's time, the injury rate for the prior year will be lower than the injury rate the year prior to the roundabout's construction. That would be a fair wager under the standards used for evaluating the safety of intersections by traffic engineers in the United States, which rightly ignore data from the period of construction and driver adjustment to an intersection reconfiguration.

I look forward to you dredging this comment out for discussion and you conceding my win circa 2020, when the rest of us have moved on to other debates.

[tradephoric]

https://www.youtube.com/watch?v=JWSfEySY_C4

[tradephoric]

A bunch of triple-lane roundabouts are opening to traffic along Franklin Blvd in Cambridge, Ontario.  Based on the performance of other roundabouts in the region i doubt these will work out too well.  But i just love Marilyn Gummerson honesty lol

"I hate them.  They're useless.  Most people do not even know how to use a roundabout properly... me included".

http://kitchener.ctvnews.ca/mixed-reviews-in-early-days-of-franklin-boulevard-roundabouts-1.3065887

[tradephoric]

The Dublin roundabout opened on August 13th and this September 14th article indicates that there have been 23 crashes since opening (the intersection only averaged 1 crash per month before the roundabout).  Lordsutch predicted the roundabout would see a reduction in the crash frequency... they were only wrong by a factor of 23.

http://abc6onyourside.com/news/local/dublin-police-targeting-new-roundabout-violators

Anybody who thinks crashes at this complex Dublin roundabout will drop from 23 per month to 1 per month as people get more familiar driving it are complete idiots.  A crash per month would match the pre-roundabout crash rate but it's not going to happen.  But this is what will happen.  An article will come out in 6 months saying crashes are down at the Dublin roundabout (when compared to the initial spike in crashes) and some idiot will say "see, told you... the roundabout is working fine" .   It's happened before on this thread.  People have no concept of a what a crash rate is.  They actually think their anecdotal evidence of driving through a roundabout once or twice a day is meaningful.  Here's renegade's through process... "heck, if i haven't seen a crash at the roundabout it must not be that bad".  It is that bad.

I think I'll leave this here ...

http://www.mlive.com/news/ann-arbor/index.ssf/2016/04/road_commission_improves_state.html#incart_river_home

Number of crashes at State and Ellsworth roundabout drops following initial spike

It's getting better.  The idiots are beginning to learn how to navigate it.  And it's not nearly as bad as someone who does not live here makes it out to be.  I have to deal with it every day, and have yet to see an accident.  I don't think anyone has died there, either.

[tradephoric]

When someone says there is a 90% reduction in fatalities at roundabouts they are referencing the safety statistics published in 2000 Insurance Institute for Highway Safety roundabout study.   Here are a few relevant snippets taken from that study:

For the group of 7 urban multilane roundabouts, however, the estimated effect on all crash severities combined was smaller – a 15 percent reduction. Because injury data were not available for the period before construction of 4 of these roundabouts, overall estimates for changes in injury crashes were not computed for this group of intersections.

The study admits that they didn't have before injury crash data for 4 of the 7 urban multilane roundabouts included in the study.  Over half of the urban multi-lane roundabouts analyzed in this national study didn't have before injury crash data. 

For completeness, partial results also are given for individual conversions in a group. Readers are cautioned about drawing conclusions from these results because there is a significant likelihood that the change in safety for individual conversions is due to chance.

Again, there are so few multi-lane roundabouts analyzed in this IIHS study that it's difficult to make any meaningful safety conclusions.  The IIHS study only analyzed 3 urban multi-lane roundabouts that had before/after injury crash data.

Effects on fatal crashes and those causing incapacitating injuries are more difficult to measure due to the small samples, but indications are that such crashes were substantially reduced. For the 20 converted intersections with injury data, there were 3 fatal crashes during the before period and none during the after period. The fatal crashes may have contributed to the fact that the roundabouts were constructed and may therefore contribute to the regression-to-the-mean phenomenon. There were 27 incapacitating injury crashes during the before period and only 3 during the after period. Taking into account the durations of the before and after periods and increases in traffic volume, and adjusting for regression to the mean (estimated to be roughly 22 percent), the observed value of 3 incapacitating or fatal injury crashes during the after period is substantially and significantly less than the 26.6 expected.  The estimated reduction in fatal and incapacitating injury crashes is 89 percent (p<0.001).

It's a technical way to say they made up the 89% reduction in fatal crashes.  Too little data and too many assumptions were made when coming up with that 89% number.   I get blasted for pointing out that 3 of the last 4 fatal crashes in Carmel have happened inside roundabouts but it's perfectly fine for agencies to cite that roundabouts reduce fatal crashes by 90% based on questionable IIHS safety statistics.

[cjw2001]

We will just have to agree to disagree.  You can continue to get your enjoyment by ranting against our roundabouts.   I'll continue to enjoy the stress free driving without traffic jams, reduced travel times and the improved gas mileage they provide.  As I said before, we are looking forward to the next 32 roundabouts being added and have no desire to go back to the stop and go traffic jams at the four way stops and traffic lights that were eliminated by the first 100 roundabouts in Carmel.

[cl94]

Of course, who knows how many of the roundabout incidents are due to stupidity of contractors and police departments. The NY 85/140 roundabout was on yesterday's Albany meet and the idiot cops in Bethlehem coned off the inner lane and the truck apron. A truck got stuck in there because it couldn't navigate the turn.

[kalvado]

We will just have to agree to disagree.  You can continue to get your enjoyment by ranting against our roundabouts.   I'll continue to enjoy the stress free driving without traffic jams, reduced travel times and the improved gas mileage they provide.  As I said before, we are looking forward to the next 32 roundabouts being added and have no desire to go back to the stop and go traffic jams at the four way stops and traffic lights that were eliminated by the first 100 roundabouts in Carmel.

sure, just don't ask for federal or state  funding when you need to bulldoze them off

[jakeroot]

We will just have to agree to disagree.  You can continue to get your enjoyment by ranting against our roundabouts.   I'll continue to enjoy the stress free driving without traffic jams, reduced travel times and the improved gas mileage they provide.  As I said before, we are looking forward to the next 32 roundabouts being added and have no desire to go back to the stop and go traffic jams at the four way stops and traffic lights that were eliminated by the first 100 roundabouts in Carmel.

sure, just don't ask for federal or state  funding when you need to bulldoze them off

This is the second time you've brought up the cost of demolition. Why does this matter so much? Ideally, you build an intersection that has the longest life span. The development patterns of Carmel fit roundabouts well.

[tradephoric]

This is the second time you've brought up the cost of demolition. Why does this matter so much? Ideally, you build an intersection that has the longest life span. The development patterns of Carmel fit roundabouts well.

They may not rip them out completely but safety improvements can be costly.  Take the Jacaranda Blvd and Venice Road roundabout that was constructed in 2011.  The city just approved $585,000 dollars in federal funds to "fix"  this crash prone roundabout.  It's only 5 years old and they already got to spend a half million to fix it.

http://www.mysuncoast.com/news/local/jacaranda-roundabout-approved-for-improvements-to-minimize-accidents/article_c52eb3a8-2e26-11e6-ad17-1bbc2c4a7e92.html

Or take the 14th and Superior roundabout that opened in 2012.  They are planning on spending $888,885 to replace temporary fencing in the median with more aesthetically pleasing dividers (they believe the fencing helps slow drivers as they approach the roundabout... but the temporary fencing looks ugly).  In addition, the plan calls for a statue to be built in the middle of the roundabout (the fixed object statue is a nice touch for this "safety improvement" ).  This roundabout is only 4 years old and they are going to spend nearly a million dollars on upgrades. 

http://www.1011now.com/content/news/More-updates-likely-coming-to-14th--Superior-roundabout-373306771.html

[tradephoric]

We will just have to agree to disagree.  You can continue to get your enjoyment by ranting against our roundabouts.   I'll continue to enjoy the stress free driving without traffic jams, reduced travel times and the improved gas mileage they provide.  As I said before, we are looking forward to the next 32 roundabouts being added and have no desire to go back to the stop and go traffic jams at the four way stops and traffic lights that were eliminated by the first 100 roundabouts in Carmel.

There isn't much common ground between us when you have such a cavalier attitude towards anyone who has been injured or killed at a roundabout.

Those stats sounds reasonable -- you most likely have to be driving impaired, speeding, or doing something else really stupid to get killed in a roundabout.  The high percentage of single vehicle crashes speaks volumes.   Good find on the stats.

You've once again quoted a single vehicle incident as a problem with the roundabout.   If an idiot driver in the middle of the night runs off the road at high speed, how is that the roundabout's fault?

What happened to the concept of personal responsibility?   If you drive like an idiot you live (or die) with the consequences.  These are the same people that would have blown the stop sign and taken out another car when it was a stop controlled intersection -- I'm much happier with them being stopped by an inanimate object rather than another vehicle.

On September 21st Ventura County firefighter Ryan Osler died in a rollover crash at the Highway 246 roundabout east of Lompoc.  He was on his way to fight the Canyon fire at Vandenberg Air Force Base.   Are you going to take the opportunity to call Ryan an "idiot" ?

https://www.youtube.com/watch?v=F1Re6ppKvO0

[kalvado]

We will just have to agree to disagree.  You can continue to get your enjoyment by ranting against our roundabouts.   I'll continue to enjoy the stress free driving without traffic jams, reduced travel times and the improved gas mileage they provide.  As I said before, we are looking forward to the next 32 roundabouts being added and have no desire to go back to the stop and go traffic jams at the four way stops and traffic lights that were eliminated by the first 100 roundabouts in Carmel.

sure, just don't ask for federal or state  funding when you need to bulldoze them off

This is the second time you've brought up the cost of demolition. Why does this matter so much? Ideally, you build an intersection that has the longest life span. The development patterns of Carmel fit roundabouts well.

Not demolition only, but reconstructing workable traffic pattern would cost what, 2-3 million per circle?

[DaBigE]

Or take the 14th and Superior roundabout that opened in 2012.  They are planning on spending $888,885 to replace temporary fencing in the median with more aesthetically pleasing dividers (they believe the fencing helps slow drivers as they approach the roundabout... but the temporary fencing looks ugly).  In addition, the plan calls for a statue to be built in the middle of the roundabout (the fixed object statue is a nice touch for this "safety improvement" ).  This roundabout is only 4 years old and they are going to spend nearly a million dollars on upgrades. 

http://www.1011now.com/content/news/More-updates-likely-coming-to-14th--Superior-roundabout-373306771.html

That spending is completely independent of any new safety improvements. What they're proposing are purely aesthetic "improvements" and thus should not be lumped into the total cost of the roundabout as you're attempting to do.

[DaBigE]

On September 21st Ventura County firefighter Ryan Osler died in a rollover crash at the Highway 246 roundabout east of Lompoc.  He was on his way to fight the Canyon fire at Vandenberg Air Force Base.   Are you going to take the opportunity to call Ryan an "idiot" ?

Labels and name-calling aside, I'm very interested to see the final crash report on this one. Based on the media reports I've seen so far, it sounds like it must have been pretty-dense fog, as it looks like that intersection is illuminated, maybe not as bright as other agencies would illuminate an intersection. Further, the warning sign had a flashing beacon, something many roundabouts do not use, yet don't typically have a similar crash issue. Source

Becker said fire truck drivers from outside the area might not know what to expect.

I'm at a loss for words on that comment.

[tradephoric]

That spending is completely independent of any new safety improvements. What they're proposing are purely aesthetic "improvements" and thus should not be lumped into the total cost of the roundabout as you're attempting to do.

This was taken directly from the City of Lincoln's Public Works website giving an overview of the project:

When the 14th and Superior roundabout was initially built and opened to traffic the crash rate was higher than anticipated. We had the configuration of the initial roundabout studied and the results showed that we needed to reduce the number of lanes and also reduce the sight distance at the roundabout. One lane in each direction was removed with traffic control devices. The site distance was limited by constructing chain link fence with slats in the medians.

The devices have been in place for approximately two years. The results show that the crash rate has been reduced significantly by the lane reduction and the fencing. At this point we are moving ahead with making the temporary adjustments to the roundabout more permanent. Concept plans have been developed to show putting tack on median concrete in place of the lane reductions. This will allow us to remove the traffic control devices along the outer lanes. A landscaping plan was developed for the center island of the roundabout and the medians. The landscaping and a short decorative fence have been shown to take the place of the chain link fence.

Along with this work a piece of artwork will be loaned to the city from the Duncans to be placed in the center of the roundabout. Construction on the more permanent fixes for the roundabout could begin as early as Fall of 2016.
https://www.lincoln.ne.gov/city/pworks/projects/14th/superior-safety/

The city is spending money to make the temporary safety adjustments to the roundabout more permanent.  The city wouldn't be spending all this money on decorative fencing if the crash rate at the roundabout hadn't been higher than expected when it first opened to traffic.  You can argue that it's not a "safety improvement" but it really is.  The decorative fencing is replacing the temporary chain link fence that was installed a few years ago.

[DaBigE]

That spending is completely independent of any new safety improvements. What they're proposing are purely aesthetic "improvements" and thus should not be lumped into the total cost of the roundabout as you're attempting to do.

This was taken directly from the City of Lincoln's Public Works website giving an overview of the project:

When the 14th and Superior roundabout was initially built and opened to traffic the crash rate was higher than anticipated. We had the configuration of the initial roundabout studied and the results showed that we needed to reduce the number of lanes and also reduce the sight distance at the roundabout. One lane in each direction was removed with traffic control devices. The site distance was limited by constructing chain link fence with slats in the medians.

The devices have been in place for approximately two years. The results show that the crash rate has been reduced significantly by the lane reduction and the fencing. At this point we are moving ahead with making the temporary adjustments to the roundabout more permanent. Concept plans have been developed to show putting tack on median concrete in place of the lane reductions. This will allow us to remove the traffic control devices along the outer lanes. A landscaping plan was developed for the center island of the roundabout and the medians. The landscaping and a short decorative fence have been shown to take the place of the chain link fence.

Along with this work a piece of artwork will be loaned to the city from the Duncans to be placed in the center of the roundabout. Construction on the more permanent fixes for the roundabout could begin as early as Fall of 2016.
https://www.lincoln.ne.gov/city/pworks/projects/14th/superior-safety/

The city is spending money to make the temporary safety adjustments to the roundabout more permanent.  The city wouldn't be spending all this money on decorative fencing if the crash rate at the roundabout hadn't been higher than expected when it first opened to traffic.  You can argue that it's not a "safety improvement" but it really is.  The decorative fencing is replacing the temporary chain link fence that was installed a few years ago.

You made no mention about adjustments to the concrete in your original post, only the replacement of the temporary fencing/aesthetic improvements...that's what my cost comment was based on. Now the cost seems a tad more understandable, unfortunate, but understandable. Regardless, since you keep harping on the replacement of the fence, the safety improvement has already been made. There is no reason that the chain link fence could not have remained in place. Changing something from "ugly" is not a safety improvement, at least not in an engineering sense.

[tradephoric]

^^^
By the City's own admission the chain link fencing was a temporary measure.  They never had any intention to keep the chain link fencing in place.  If it was shown to be ineffective at reducing crashes they would have ripped it out.  If it was shown to reduce crashes (as they believe it did) they would replace it with permanent fencing.  But there's a bigger issue here then what type of fence the city decided to use.  How does the city know the fencing was effective at reducing crashes at the roundabout in the first place?  The problem is at the same time they installed the fencing they removed a circulating lane of traffic inside the roundabout.  Those two changes combined saw a reduction in crashes at the roundabout, but how do we know if the reduction was due to the fencing or the reduction of a circulating lane? 

Luckily, they have added fencing at the most crash prone roundabout in Michigan (186 crashes in 2015).  No other changes were made other than the fencing so we will see if it actually helps reduce the total number of crashes.  By the way, it looks like there was a Police car responding to a crash at the roundabout the day this news report was done (hmmm.... the fences were in place and people are still crashing into each other at this roundabout).  Big shock! 

http://www.wxyz.com/news/region/oakland-county/drivers-have-mixed-feelings-about-new-fences-at-m-5-roundabout

[DaBigE]

By the way, it looks like there was a Police car responding to a crash at the roundabout the day this news report was done (hmmm.... the fences were in place and people are still crashing into each other at this roundabout).  Big shock! 

No one ever said it would prevent all crashes. There is no such intersection control which will do that.

We get it; quite a few roundabouts have seen an increase in crashes, yet you keep harping on the same old information over, and over, and over. We're also still learning about roundabouts in this country, both from a design and a driver perspective. It doesn't help that we cannot all agree on capacity equations, which has led to some roundabouts being built larger than what they need to be. Unfortunately, there are two big variables that are still in a state of flux: traffic projections and driver behavior at a roundabout -- how to properly account for timid vs. aggressive drivers. And unfortunately, this cannot be tested completely in a laboratory environment.

Are roundabouts perfect? No. Are they a silver-bullet solution? Not even close. What they are is another tool in the toolbox -- a tool which is still working thru some R&D revisions.

[kalvado]

Are roundabouts perfect? No. Are they a silver-bullet solution? Not even close. What they are is another tool in the toolbox -- a tool which is still working thru some R&D revisions.

Perfectly put. Problem is I don't see  too much R&D  - or that is just me?

[tradephoric]

No one ever said it would prevent all crashes. There is no such intersection control which will do that.

All I did was point out a simple observation — that there was a police vehicle responding to an apparent accident at the roundabout.  I'm not suggesting one way or another if the fencing will be effective at reducing the high number of crashes that are occurring at the M-5 / Pontiac Trail roundabout. 

I am questioning how Lincoln officials knew the fencing was effective at the Superior roundabout when the lane reduction was part of the safety improvement.  I contend that the reduction in crashes may be due to the fact they converted the roundabout from a complex 2x3 roundabout into a simplified 1x2 configuration.   DaBigE, do you know of any literature that suggests the fencing placed down splitter islands can be effective at reducing crashes?  I've never seen such a study and would be interested in reading it.

[DaBigE]

I contend that the reduction in crashes may be due to the fact they converted the roundabout from a complex 2x3 roundabout into a simplified 1x2 configuration.   DaBigE, do you know of any literature that suggests the fencing placed down splitter islands can be effective at reducing crashes?  I’ve never seen such a study and would be interested in reading it.

There are no formal reports that I am aware of at the moment, however there are several locations that have recently attempted to restrict sight to the left on the entry with either fencing or vegetation as a crash mitigation technique. It's almost purely a psychological effect. In theory, the less the driver can see should cause the driver to reduce their speed, thus increasing the likelihood of proper yield on entry behavior. Put another way, unless you're actively being pursued by the cops, how many of you would come barreling down a narrow, building-lined alley at 30 mph when approaching a crossroad?

Unfortunately, the after crash data is not available just yet, but rumors are that it has made a positive difference. With many of the locations, this is the only treatment that has been done, so it should better prove the effectiveness of restricting entering sight distance.

In the case of locations where multiple mitigation techniques have been introduced at the same time, and if the crashes are reported/coded properly, you should be able to get an idea which technique has had an effect. Reducing the number of circulating lanes generally results in less exit/entering crossing crashes. But again, you're at the mercy of the accuracy of the officer reporting the crash. After having reviewed hundreds of crash reports (both roundabout and non-roundabout-related) and having watched reports be actively completed in several ride-alongs, my faith isn't exactly high, especially with municipal officers.