Crash prone 'modern roundabouts'

[tradephoric]

Now you're just being silly. For example, road diets are designed to slow drivers down because drivers generally drive slower in narrower lanes (9' to 11' lanes rather than 12'+), with closer curbs, etc. Yet there's no physical impediment to using a dieted road as a drag strip, so I guess road diets don't actually work.

It's one thing to say roundabouts are designed to slow drivers down.   But that's not what the Insurance Institute for Highway Safety is claiming.  On their main website they state that the tight circle of a roundabout "forces"  drivers to slow down.  There is a distinction there.  This woman in Britain wasn't forced to slow down as she approached a roundabout:

http://www.liverpoolecho.co.uk/news/liverpool-news/shocking-video-shows-car-launched-12874854

The IIHS makes a ludicrous claim that is easily disproven by watching a 20 second youtube video.  This is the same agency that has long propagated the myth that roundabouts reduce fatal crashes by 90%.  Their findings come into question when they can't even get a simple statement on their website right.

[kalvado]

A driver blowing through a roundabout and flying 50 feet over a cliff is evidence that roundabouts don't force drivers to slow down.  With their logic I could make the argument that traffic signals are safer than roundabouts because red lights force drivers to stop - at roundabouts you merely slow down.   If they can't even get the premise right, why would anyone believe their dubious claim that roundabouts reduce fatal crashes by 90%? 

Now you're just being silly. For example, road diets are designed to slow drivers down because drivers generally drive slower in narrower lanes (9' to 11' lanes rather than 12'+), with closer curbs, etc. Yet there's no physical impediment to using a dieted road as a drag strip, so I guess road diets don't actually work.

As I said multiple times, the root cause problem is quality of engineering personnel.
Roads are designed for average Joe. Maybe for 80 years old aunt Mary and her husband who is still driving. For those college kids who have more hormones than brains. And roads MUST be designed with them in mind.
If it was about designing NASCAR track, requirements may be different. But there is a clear sign of accident pattern observable in that area - even on google maps.
That is design problem.
That is engineering problem.
In private company such performance failure would be a reason for firing, plain and simple.
 

How did those accidents happen with the guardrail?

If there was 3 separate accidents, and 3 different causes, what was the design problem?

What if an accident was caused by a deer running thru the roundabout?  Or someone blew a tire?  The guardrail SAVED their lives.  Simply because a guardrail was hit doesn't mean there's a design problem.  On the contrary, the guardrail was designed properly.

By your and Trade's logic, we should never have guardrails anywhere ever, because that reveals a design problem when hit.

Well, at least they managed design guardrail. Problem is that it acted not as a backup, which should be used only a few times during life - but pretty much as a primary system, with what appears to be quite frequent collisions. In such situation, it is only a matter of time that a fatal accident... And usually fatal accident is the reason to review situation - so we may hope for the best...

[Brian556]

Google Map of the location:
https://www.google.com/maps/@35.0097643,-85.2696198,371m/data=!3m1!1e3

There is plenty of warning of what comes after the tunnel. The single narrow lane in tunnel encourages low speeds.

The roundabout at he end of the tunnel makes the situation no more dangerous then before it was installed.

I don't see anything particularly unsafe engineering wise that would be the cause of these accidents.

I think the problem here is simply that some people stupid and should not be driving

[kphoger]

Maybe it was an epic multi-year police chase .  The roundabout crash is relevant in that it dispels the whole premise of why roundabouts are safer.  Just read what the Insurance Institute for Highway Safety website says...

[img width=800 height=679]...

A driver blowing through a roundabout and flying 50 feet over a cliff is evidence that roundabouts don't force drivers to slow down.  With their logic I could make the argument that traffic signals are safer than roundabouts because red lights force drivers to stop - at roundabouts you merely slow down.   If they can't even get the premise right, why would anyone believe their dubious claim that roundabouts reduce fatal crashes by 90%? 

Fallacy of equivocation.

"Force" is not intended to mean what you make it out to mean.  A giant center island, landscaping (maybe), curved/flared entries, warning signs (often with flashing warning lights of their own), et cetera certainly do a better job of "forcing" a driver to slow down than a couple of lights hung above an otherwise straightforward intersection.  There are simply more and bigger things for a driver to notice, and there are physical realities that lead any but the most unobservant driver to slow down.  This doesn't mean the spirit of a roundabout inhabits the body of a drive and moves his foot over onto the brake.  But that's not what the word "force" means in the context of the IIHS blurb you posted.

As to your reworking of their logic:  A stoplight is just as likely to make (notice how I use that word in a non-literal sense) a driver speed up as slow down.  Yellow light? speed up!  You can't speed up to beat a red roundabout.

[kalvado]

Google Map of the location:
https://www.google.com/maps/@35.0097643,-85.2696198,371m/data=!3m1!1e3

There is plenty of warning of what comes after the tunnel. The single narrow lane in tunnel encourages low speeds.

And since there is still a pattern, it means that there is not enough warning.  I mean, advance signage and and so on. You design for realities of life, not to what you think it should be.

There is obviously a hazard in the way tunnel and street are aligned, no question about that. It takes some effort to design things so that they actually work, not just pass a half-assed review process.

The roundabout at he end of the tunnel makes the situation no more dangerous then before it was installed.

So spending something like one million dollars TennDOT managed to make things not worse than they were. That is a great achievement, oftentimes it takes billions to achieve same "it wasn't better" result

I think the problem here is simply that some people stupid and should not be driving

I think some engineers are  stupid and should not be designing things. I also think that is easier to accomplish in terms of affected headcount.

[jeffandnicole]

Google Map of the location:
https://www.google.com/maps/@35.0097643,-85.2696198,371m/data=!3m1!1e3

There is plenty of warning of what comes after the tunnel. The single narrow lane in tunnel encourages low speeds.

And since there is still a pattern, it means that there is not enough warning.  I mean, advance signage and and so on. You design for realities of life, not to what you think it should be.

What's the pattern?  How can you tell those guardrail hits all occurred the same way?

[intelati49]

Google Map of the location:
https://www.google.com/maps/@35.0097643,-85.2696198,371m/data=!3m1!1e3

There is plenty of warning of what comes after the tunnel. The single narrow lane in tunnel encourages low speeds.

And since there is still a pattern, it means that there is not enough warning.  I mean, advance signage and and so on. You design for realities of life, not to what you think it should be.

There is obviously a hazard in the way tunnel and street are aligned, no question about that. It takes some effort to design things so that they actually work, not just pass a half-assed review process.

The roundabout at he end of the tunnel makes the situation no more dangerous then before it was installed.

So spending something like one million dollars TennDOT managed to make things not worse than they were. That is a great achievement, oftentimes it takes billions to achieve same "it wasn't better" result

I think the problem here is simply that some people stupid and should not be driving

I think some engineers are  stupid and should not be designing things. I also think that is easier to accomplish in terms of affected headcount.

I have no idea what the traffic situation is like here, but safety isn't the only warrant for a intersection change. Capacity is another, and they probably thought they could get more traffic through here.

And I wanted to reply to the last quote with a joke, but I guess a statement will suffice. Nobody wants to pay for a 99.9% safe road (14ft lanes with 1000ft sightlines), so 95% safe roads have to suffice. There's only so much you can do without making the markings a distraction

[TheArkansasRoadgeek]

I love how we resort to the second generation of interchanges to solve a hazardous problem in an intersection. You would think we are pushing forward in transportation engineering not going backward. Weird.

[intelati49]

I love how we resort to the second generation of interchanges to solve a hazardous problem in an intersection. You would think we are pushing forward in transportation engineering not going backward. Weird.

Hey, the saying "hindsight's 20/20" is for a reason. Sometimes we get so caught up with going forward, we forget the original ideas we had before.

[kalvado]

I love how we resort to the second generation of interchanges to solve a hazardous problem in an intersection. You would think we are pushing forward in transportation engineering not going backward. Weird.

Ypu're not pushing towards 5th generation antibiotics or GM insulin to treat flu or broken leg.
You need a lot of water and rest -  or cast, respectively.  Both are first generation treatments...

Obsession with advanced design is actually bad - until there is a clear understanding of what are problems of old methods, when they work, and when they don't - and why. 

[kphoger]

I'm not even sure what "second generation of interchanges" is supposed to mean/imply.  I wouldn't want to turn a freeway interchange into an at-grade intersection, but I also wouldn't want to turn the now-uncontrolled intersection three doors down from my house into a cloverstack.

[TheArkansasRoadgeek]

I love how we resort to the second generation of interchanges to solve a hazardous problem in an intersection. You would think we are pushing forward in transportation engineering not going backward. Weird.

Hey, the saying "hindsight's 20/20" is for a reason. Sometimes we get so caught up with going forward, we forget the original ideas we had before.

Ypu're not pushing towards 5th generation antibiotics or GM insulin to treat flu or broken leg.
You need a lot of water and rest -  or cast, respectively.  Both are first generation treatments...

Obsession with advanced design is actually bad - until there is a clear understanding of what are problems of old methods, when they work, and when they don't - and why.

Makes scense, but I just thought of how we always say we want and are pushing forward in something, and yet we are still using primitive methods of solving a problem. Noting wrong in that, but the question that comes up if we are still using old habits, is that: "Are we really improving and making progress?"

[kalvado]

I have no idea what the traffic situation is like here, but safety isn't the only warrant for a intersection change. Capacity is another, and they probably thought they could get more traffic through here.

And I wanted to reply to the last quote with a joke, but I guess a statement will suffice. Nobody wants to pay for a 99.9% safe road (14ft lanes with 1000ft sightlines), so 95% safe roads have to suffice. There's only so much you can do without making the markings a distraction

Well, traffic counts are there. 20k from the tunnel and to the right and back, 5k on a street coming from the left looking from the tunnel.
Some turn lanes in roundabout footprint should help traffic lines.
As for 99.9% safe road... Not a penny. Because 1 accident out of 1000 passing vehicles is incredibly high. If you will, it means anyone driving through the intersection will crash annually....  Aim 1 out of million, and now we're talking.

[TheArkansasRoadgeek]

I'm not even sure what "second generation of interchanges" is supposed to mean/imply.  I wouldn't want to turn a freeway interchange into an at-grade intersection, but I also wouldn't want to turn the now-uncontrolled intersection three doors down from my house into a cloverstack.

There are three generations of interchanges, Cloverleaf, Roundabout, and Stack. Just look up some history and you'll see what I was talking about.

[kphoger]

Googling "second generation of interchanges" with quotes returns exactly two hits; without quotes returns nothing useful.

And I think you might be confusing roundabout interchanges with roundabouts.  They're not the same thing.

[kalvado]

I love how we resort to the second generation of interchanges to solve a hazardous problem in an intersection. You would think we are pushing forward in transportation engineering not going backward. Weird.

Hey, the saying "hindsight's 20/20" is for a reason. Sometimes we get so caught up with going forward, we forget the original ideas we had before.

Ypu're not pushing towards 5th generation antibiotics or GM insulin to treat flu or broken leg.
You need a lot of water and rest -  or cast, respectively.  Both are first generation treatments...

Obsession with advanced design is actually bad - until there is a clear understanding of what are problems of old methods, when they work, and when they don't - and why.

Makes scense, but I just thought of how we always say we want and are pushing forward in something, and yet we are still using primitive methods of solving a problem. Noting wrong in that, but the question that comes up if we are still using old habits, is that: "Are we really improving and making progress?"

Excellent question.
there is one ideology called KISS - aka "keep it simple, stupid!"
Now question is what "simple" means, and how idea of "simple" changes over time.
I don't know how traffic light were driven 50 years ago; I suspect either mechanics or some tubes and relays. Today it is a small chip - which can do much more.
What "simple" means in this case - advanced chip technology,  or 20 simple vacuum tubes?.. But although we have all those chips - plates spoons and forks are basically the same they were 100 years ago. Understanding where new tech actually makes life simple, and where it is more pain than gain is a big thing.
My impression - and I told that many times - understanding where roundabouts actually fit is the biggest deal here

[jakeroot]

It's one thing to say roundabouts are designed to slow drivers down.   But that's not what the Insurance Institute for Highway Safety is claiming.  On their main website they state that the tight circle of a roundabout "forces"  drivers to slow down.  There is a distinction there.  This woman in Britain wasn't forced to slow down as she approached a roundabout:

Oh for fuck's sake, trade. You are taking that claim waaaay too literally.

It does force you to slow down, lest you want to collide with nature.

We don't build our world in straight lines. There's curves and corners everywhere, man. Roundabouts are adding corners and curves where there weren't any before (maybe), but that's just the nature of the intersection. And I've yet to see any studies that show a direct correlation between the circlular nature of the intersection, and a rise in collisions or injuries. Most of the collisions seem to be failure to yield or failure to maintain lane.

[hm insulators]

Apparently, leading police on a high speed chase and hitting another car is now a fault of a roundabout.

Idiots will always be idiots, there's no helping that.

And as soon as you make something idiot-proof, along comes a bigger idiot.

[kalvado]

It’s one thing to say roundabouts are designed to slow drivers down.   But that’s not what the Insurance Institute for Highway Safety is claiming.  On their main website they state that the tight circle of a roundabout “forces” drivers to slow down.  There is a distinction there.  This woman in Britain wasn’t forced to slow down as she approached a roundabout:

Oh for fuck's sake, trade. You are taking that claim waaaay too literally.

It does force you to slow down, lest you want to collide with nature.

We don't build our world in straight lines. There's curves and corners everywhere, man. Roundabouts are adding corners and curves where there weren't any before (maybe), but that's just the nature of the intersection. And I've yet to see any studies that show a direct correlation between the circlular nature of the intersection, and a rise in collisions or injuries. Most of the collisions seem to be failure to yield or failure to maintain lane.

Well, we hope that ALL roads are designed so that an average sober driver can navigate them without an issue. Moreover, they should be designed with some safety factor in mind - e.g. interstate lane is 12', and truck standard is 8'6", if I remember correctly.
Safety factor include, among other things, enough time to respond to mistake - your or other driver. That is why we have all red phase on traffic lights.
These are examples of proper engineering for

failure to yield or failure to maintain lane

- and speed, I may add.
Looks like roundabout in question is not designed with sufficient cushion in mind. It is not only an issue of circle itself, it is an issue of, for example, signing approaches. Tunnels have their own set of issues - e.g. with line of sight and illumination - which have to be taken into account. I bet combination of "tunnel + roundabout" is not listed in any design manual..
ANd this is where engineering failed - or rather business as usual, if you ask me. They took "force to reduce speed" claim at face value....

[tradephoric]

 75-year-old woman killed in one-car Gorham roundabout

http://www.wlbz2.com/news/local/fatal-crash-closes-rte-114-bypass-in-gorham/434022792

Another example of a driver not being forced to slow down.  And of course I'm going to take the IIHS claim that roundabouts "forces" drivers to slow down literally.  Why wouldn't I?

[kphoger]

And of course I'm going to take the IIHS claim that roundabouts "forces" drivers to slow down literally.  Why wouldn't I?

Because it was not the intent.

[kphoger]

75-year-old woman killed in one-car Gorham roundabout

http://www.wlbz2.com/news/local/fatal-crash-closes-rte-114-bypass-in-gorham/434022792

So is this now a 'crash prone modern roundabout'?

[intelati49]

75-year-old woman killed in one-car Gorham roundabout

http://www.wlbz2.com/news/local/fatal-crash-closes-rte-114-bypass-in-gorham/434022792

So is this now a 'crash prone modern roundabout'?

I just realized he's the one who started this mess. We're really going around in circles right now (Pun unintentionally found in 2015 in this thread)

[tradephoric]

75-year-old woman killed in one-car Gorham roundabout

http://www.wlbz2.com/news/local/fatal-crash-closes-rte-114-bypass-in-gorham/434022792

So is this now a 'crash prone modern roundabout'?

Any intersection where a fatal crash is involved warrants further analysis.  Most would agree that one fatal crash is worse than 100 property damage only crashes.

[silverback1065]

this is fucking bullshit http://currentincarmel.com/carmel-mayor-instructing-police-to-ticket-drivers-for-not-using-turn-signals-in-roundabouts
you should signal in a roundabout, but when it was voted down by the city counsel, and state law is ambiguous to the issue, you shouldn't proceed with ticketing!