Crash prone 'modern roundabouts'

[kphoger]

Here we are again. It's the roundabout's fault the woman was drunk and speeding.

With your logic there is no need to convert traffic signals to roundabouts in the first place.  When a drunk driver blows through a red light it's not the red lights fault they were drunk and speeding.  Why are we worried about fatal t-bone accidents at traffic signals when alcohol was a factor?  After all, you can't stop stupid. 

With the roundabout that dramatically minimizes the chances this lady would have plowed into someone else.

How?  A driver crossing her path in the roundabout is (roughly) no less at a 90° angle to the other driver than one crossing a stoplighted intersection.  I guess she was less likely to hit someone on the far side of the roundabout...

[tradephoric]

With the roundabout that dramatically minimizes the chances this lady would have plowed into someone else.

Have you heard the story about the guy in Raleigh where his house has been hit 6 times?  His house has become the ultimate "bad driver"  magnet.  While the lives of him and his family are in danger, he is doing a public service by stopping all those impaired drivers before they get a chance to hurt anybody else on the road.  If drivers can hit this poor guy's house 6 times, it's not surprising that some drivers can blow straight through the center of a roundabout.

Raleigh man fed up after house hit by car for 6th time
https://abc11.com/news/raleigh-man-fed-up-after-house-hit-by-car-for-6th-time/1469768/

[jakeroot]

^^
I notice from Street View that access to his neighborhood was cut-off, and the guardrail extended, since that story was posted:

https://goo.gl/maps/jWucN8h47GAoaqtC9

[kalvado]

Here we are again. It's the roundabout's fault the woman was drunk and speeding.

With your logic there is no need to convert traffic signals to roundabouts in the first place.  When a drunk driver blows through a red light it's not the red lights fault they were drunk and speeding.  Why are we worried about fatal t-bone accidents at traffic signals when alcohol was a factor?  After all, you can't stop stupid. 

With the roundabout that dramatically minimizes the chances this lady would have plowed into someone else.

Probably increases those chances, actually.

[jakeroot]

WSDOT is building two new roundabouts near Camas (just north of the Columbia River) along WA-14. Construction started today. The two intersections are roughly at either end of this Maps link (15 St/Washougal River Rd, and 32 St).

These are relatively simple one-lane roundabouts (with one extra lane at 32 St), but what is more worrisome for me, is that they're being built just east of a brand new freeway interchange. WA-14 is basically a freeway or Super-2 from I-5 (16 miles away), all the way to this point. This would not be the first roundabout at the terminus of a freeway, but it doesn't seem like that great of an idea to me. WA-14 is either 55 or 60 from I-5, up to 15 St (the first roundabout).

I'm not trying to imply that a signal would absolutely be better. But I would assume that a signal, with a flashing "prepare to stop" message and rumble strips perpendicular to the lanes, would be better than a roundabout, as those really can sneak up on you, if you're not expecting them (which people may not be, after driving along 16 miles worth of divided highway).

[kalvado]

WSDOT is building two new roundabouts near Camas (just north of the Columbia River) along WA-14. Construction started today. The two intersections are roughly at either end of this Maps link (15 St/Washougal River Rd, and 32 St).

These are relatively simple one-lane roundabouts (with one extra lane at 32 St), but what is more worrisome for me, is that they're being built just east of a brand new freeway interchange. WA-14 is basically a freeway or Super-2 from I-5 (16 miles away), all the way to this point. This would not be the first roundabout at the terminus of a freeway, but it doesn't seem like that great of an idea to me. WA-14 is either 55 or 60 from I-5, up to 15 St (the first roundabout).

I'm not trying to imply that a signal would absolutely be better. But I would assume that a signal, with a flashing "prepare to stop" message and rumble strips perpendicular to the lanes, would be better than a roundabout, as those really can sneak up on you, if you're not expecting them (which people may not be, after driving along 16 miles worth of divided highway).

You can definitely supplement roundabout with any kind of warning that can be used for a traffic light. I thought I had an example of rumble strip before roundabout - but google maps don't show that. Hard to tell if that is my memory issue or old map data. The only thing positively unavailable is traffic light itself being located above the road right in front of the driver. 

[jakeroot]

You can definitely supplement roundabout with any kind of warning that can be used for a traffic light. I thought I had an example of rumble strip before roundabout - but google maps don't show that. Hard to tell if that is my memory issue or old map data. The only thing positively unavailable is traffic light itself being located above the road right in front of the driver.

For sure. I see plenty of warning devices used at roundabouts (WI seems to be the king of this...WSDOT is pretty bad at advanced roundabout warning signage), though I find the "when flashing" warning devices at signals to be especially effective because they aren't always flashing. They catch your eye, especially if they start flashing only as you approach the sign. With a roundabout, it would have to be constantly flashing, and I'm not certain how effective those are.

Granted, if you're not aware of the approaching roundabout, a constant flashing orb might catch your attention. So perhaps not all is lost.

[DaBigE]

You can definitely supplement roundabout with any kind of warning that can be used for a traffic light. I thought I had an example of rumble strip before roundabout - but google maps don't show that. Hard to tell if that is my memory issue or old map data. The only thing positively unavailable is traffic light itself being located above the road right in front of the driver.

For sure. I see plenty of warning devices used at roundabouts (WI seems to be the king of this...WSDOT is pretty bad at advanced roundabout warning signage), though I find the "when flashing" warning devices at signals to be especially effective because they aren't always flashing.

Effective until the light burns out or the flasher malfunctions. When that happens you get a bunch of blissfully ignorant drivers heading for a rude awakening. A few areas ban those kind of advanced signals because that potential.

[jakeroot]

You can definitely supplement roundabout with any kind of warning that can be used for a traffic light. I thought I had an example of rumble strip before roundabout - but google maps don't show that. Hard to tell if that is my memory issue or old map data. The only thing positively unavailable is traffic light itself being located above the road right in front of the driver.

For sure. I see plenty of warning devices used at roundabouts (WI seems to be the king of this...WSDOT is pretty bad at advanced roundabout warning signage), though I find the "when flashing" warning devices at signals to be especially effective because they aren't always flashing.

Effective until the light burns out or the flasher malfunctions. When that happens you get a bunch of blissfully ignorant drivers heading for a rude awakening. A few areas ban those kind of advanced signals because that potential.

That's why you install two sets of signs on either side of the carriageway, each with two lights. What are the chances that the entire assembly is going to break? And if one bulb burns out, there's still three left.



Which areas ban them? Never heard of such lunacy. BC requires them on all roads with a 70+ km/h limit.

[DaBigE]

You can definitely supplement roundabout with any kind of warning that can be used for a traffic light. I thought I had an example of rumble strip before roundabout - but google maps don't show that. Hard to tell if that is my memory issue or old map data. The only thing positively unavailable is traffic light itself being located above the road right in front of the driver.

For sure. I see plenty of warning devices used at roundabouts (WI seems to be the king of this...WSDOT is pretty bad at advanced roundabout warning signage), though I find the "when flashing" warning devices at signals to be especially effective because they aren't always flashing.

Effective until the light burns out or the flasher malfunctions. When that happens you get a bunch of blissfully ignorant drivers heading for a rude awakening. A few areas ban those kind of advanced signals because that potential.

That's why you install two sets of signs on either side of the carriageway, each with two lights. What are the chances that the entire assembly is going to break? And if one bulb burns out, there's still three left.

Which areas ban them? Never heard of such lunacy. BC requires them on all roads with a 70+ km/h limit.

Let me rephrase that, some ban the concept of "when flashing" text being associated with an advanced traffic signal or railroad warning sign. WisDOT is one of them*. They will allow the phase on signs of lesser importance, like highway advisory radio signs. They allow flashing beacons to be associated with intersection control warning signs, but they have to flash 24/7.

*Note, I was told this many years ago by a former state signalling engineer; however, I have not been able to find the supporting text in their guides and manuals beyond ties to railroad crossings. It may have been another 'verbal policy' that has sticking power among the decision makers.

You also have to remember that many of these systems, despite being on both sides of the carriageway, are fed by a common power conduit. One short upstream of the beacons, and neither one of them work.

[jakeroot]

You also have to remember that many of these systems, despite being on both sides of the carriageway, are fed by a common power conduit. One short upstream of the beacons, and neither one of them work.

That seems like it would be unusual, but I'll give you the benefit of the doubt. But consider this: how are we to say that the net-negative effects of an inoperable PTSWF sign are of greater significance than the net-positive effects of an operable PTSWF sign? Both in contrast to not having a sign at all.

[DaBigE]

You also have to remember that many of these systems, despite being on both sides of the carriageway, are fed by a common power conduit. One short upstream of the beacons, and neither one of them work.

That seems like it would be unusual, but I'll give you the benefit of the doubt. But consider this: how are we to say that the net-negative effects of an inoperable PTSWF sign are of greater significance than the net-positive effects of an operable PTSWF sign? Both in contrast to not having a sign at all.

I think you're making this a lot more complicated than it needs to be. Just let them flash constantly. What does it hurt? It also simplifies the wiring and programming needs. Having 24/7 flash and no sign has a better/safer driver default response than with the PTSWF. One could also say the part-time flash and sign is not necessary, as being prepared to possibly have to stop should be assumed with the Signal Ahead warning sign.

[kalvado]

You can definitely supplement roundabout with any kind of warning that can be used for a traffic light. I thought I had an example of rumble strip before roundabout - but google maps don't show that. Hard to tell if that is my memory issue or old map data. The only thing positively unavailable is traffic light itself being located above the road right in front of the driver.

For sure. I see plenty of warning devices used at roundabouts (WI seems to be the king of this...WSDOT is pretty bad at advanced roundabout warning signage), though I find the "when flashing" warning devices at signals to be especially effective because they aren't always flashing.

Effective until the light burns out or the flasher malfunctions. When that happens you get a bunch of blissfully ignorant drivers heading for a rude awakening. A few areas ban those kind of advanced signals because that potential.

That's why you install two sets of signs on either side of the carriageway, each with two lights. What are the chances that the entire assembly is going to break? And if one bulb burns out, there's still three left.



Which areas ban them? Never heard of such lunacy. BC requires them on all roads with a 70+ km/h limit.

This is actually an install which I find a bit prone to specific problem:
in case of larger-scale power outage, a driver who is not aware of the situation would assume that traffic light is off by design and they don't need to stop - and end up running inop light assuming they have right of the way. So power outage creates a significantly difficult situation
Rewording "prepare to stop" with light just to attract attention eliminates that scenario.

[MNHighwayMan]

in case of larger-scale power outage, a driver who is not aware of the situation would assume that traffic light is off by design and they don't need to stop

This seems like a bit of a reach. (Edit: Normal) traffic signals are never "off by design," so I find it improbable that any driver would ever think this.

[jamess]

in case of larger-scale power outage, a driver who is not aware of the situation would assume that traffic light is off by design and they don't need to stop

This seems like a bit of a reach. Traffic signals are never "off by design," so I find it improbable that any driver would ever think this.

Thanks to the wonders of the HAWK, this is not true!

[DaBigE]

in case of larger-scale power outage, a driver who is not aware of the situation would assume that traffic light is off by design and they don't need to stop

This seems like a bit of a reach. (Edit: Normal) traffic signals are never "off by design," so I find it improbable that any driver would ever think this.

Years ago, I would agree with you, but you can't assume common sense with most of today's drivers.

[kalvado]

in case of larger-scale power outage, a driver who is not aware of the situation would assume that traffic light is off by design and they don't need to stop

This seems like a bit of a reach. (Edit: Normal) traffic signals are never "off by design," so I find it improbable that any driver would ever think this.

Years ago, I would agree with you, but you can't assume common sense with most of today's drivers.

You cannot assume common sense in design either.
If speed limit can be changed with illuminated sign - higher limit when dark; HAWK mentioned above; FYA which is in a class of its own... Traffic light only active during rush hour is easy to envision.

[tradephoric]

Studies have found that HAWK signals at roundabouts have a high non-compliance rate among drivers.  Based on a 2011 HAWK study done by Western Michigan University, 12.9% of drivers exiting the roundabout proceeded through the crosswalk when the HAWK signal was displaying a Steady Red/Walk and 24.4% of exiting drivers proceeded through the crosswalk when the HAWK was displaying Flashing Red/Flashing Don't Walk.  Not only can HAWK signals be ineffective at roundabouts, they add additional poles in the vicinity of the roundabout that an out of control driver may strike.  Here is an aerial of the 14 Mile & Orchard Lake roundabout and the roughly 20 poles surrounding it.



Driving through street-view, you can see a steel light pole laying on the ground next to the roundabout (presumably to replace a light pole that had previously been taken out)


And a few weeks ago a driver struck a mast-arm pole 300 feet north of the roundabout.  The impact nearly split the car in two.   While it was initially reported that the crash occurred at the roundabout itself, the driver did not drive through the roundabout before striking the pole.  However, it does show the potential dangers of striking a solid steel pole which this roundabout is littered with.  If you lose control near this roundabout you would be hard pressed not to strike a steel pole. 


1 dead, 1 injured in crash at Northwestern Highway, Orchard Lake Road following chase
https://www.clickondetroit.com/news/1-dead-1-injured-in-crash-at-northwestern-highway-orchard-lake-road-following-chase

[kphoger]

You can definitely supplement roundabout with any kind of warning that can be used for a traffic light. I thought I had an example of rumble strip before roundabout - but google maps don't show that.

Oh yeah, I've definitely seen advance warnings for roundabouts.  Here is a set of rumble strips on US-50 approaching US-77.  Here's one on US-400 approaching KS-47.  Here's one on US-60 approaching MO-43.  And, after doing some internet searching, here's a flashing beacon on CA-246 approaching Purisima Road

[DaBigE]

Studies have found that HAWK signals at roundabouts have a high non-compliance rate among drivers.  Based on a 2011 HAWK study done by Western Michigan University, 12.9% of drivers exiting the roundabout proceeded through the crosswalk when the HAWK signal was displaying a Steady Red/Walk and 24.4% of exiting drivers proceeded through the crosswalk when the HAWK was displaying Flashing Red/Flashing Don't Walk.  Not only can HAWK signals be ineffective at roundabouts, they add additional poles in the vicinity of the roundabout that an out of control driver may strike.  Here is an aerial of the 14 Mile & Orchard Lake roundabout and the roughly 20 poles surrounding it.



Driving through street-view, you can see a steel light pole laying on the ground next to the roundabout (presumably to replace a light pole that had previously been taken out)


And a few weeks ago a driver struck a mast-arm pole 300 feet north of the roundabout.  The impact nearly split the car in two.   While it was initially reported that the crash occurred at the roundabout itself, the driver did not drive through the roundabout before striking the pole.  However, it does show the potential dangers of striking a solid steel pole which this roundabout is littered with.  If you lose control near this roundabout you would be hard pressed not to strike a steel pole. 


1 dead, 1 injured in crash at Northwestern Highway, Orchard Lake Road following chase
https://www.clickondetroit.com/news/1-dead-1-injured-in-crash-at-northwestern-highway-orchard-lake-road-following-chase

HAWK compliance aside, updated signalized intersections aren't much less dangerous with regard to non-breakaway steel poles. This one has 9 such poles (not including those used for overhead lane control signs) on a high-speed corridor.

[jamess]

  Here is an aerial of the 14 Mile & Orchard Lake roundabout and the roughly 20 poles surrounding it.

Garbage roundabout. Note the lack of deflection on exit, so drivers are accelerating rapidly into the crosswalk.

[kalvado]

  Here is an aerial of the 14 Mile & Orchard Lake roundabout and the roughly 20 poles surrounding it.

Garbage roundabout. Note the lack of deflection on exit, so drivers are accelerating rapidly into the crosswalk.

Garbage roundabout sounds like dirty trash or wet water to me.

[jeffandnicole]

  Here is an aerial of the 14 Mile & Orchard Lake roundabout and the roughly 20 poles surrounding it.

Garbage roundabout. Note the lack of deflection on exit, so drivers are accelerating rapidly into the crosswalk.

Isn't that how a roundabout is properly designed, with less deflection on exit?

The problem with roundabout crosswalks is that it only leaves room for a car or two to stop, before traffic behind them would be stopped within the crosswalk.  It also created a sight-hazard - as motorists are looking left for traffic coming into the roundabout, a motorist probably isn't looking to the right where the stopped traffic would be located.

Note to the left of the picture.  Those crosswalks are much further away from the roundabout. Much better location there.

[jamess]

  Here is an aerial of the 14 Mile & Orchard Lake roundabout and the roughly 20 poles surrounding it.

Garbage roundabout. Note the lack of deflection on exit, so drivers are accelerating rapidly into the crosswalk.

Isn't that how a roundabout is properly designed, with less deflection on exit?

The problem with roundabout crosswalks is that it only leaves room for a car or two to stop, before traffic behind them would be stopped within the crosswalk.  It also created a sight-hazard - as motorists are looking left for traffic coming into the roundabout, a motorist probably isn't looking to the right where the stopped traffic would be located.

Note to the left of the picture.  Those crosswalks are much further away from the roundabout. Much better location there.

Properly designed depends on what standard youre using.

If youre US highway metrics like "vehicles per hour", then yes, the straighter the better.

If your metric is safety, than no. Compare to a European roundabout, where the deflection to exit is similar as the one to enter



In the Michigan example, they had to add a HAWK because clearly compliance at the crosswalk was minimal.

[kalvado]

Properly designed depends on what standard youre using.

If youre US highway metrics like "vehicles per hour", then yes, the straighter the better.

If your metric is safety, than no. Compare to a European roundabout, where the deflection to exit is similar as the one to enter

Problem is that to put pedestrian safety first you need to put roundabouts in spots with traffic low enough to sustain reduced roundabout performance. THis is where US engineering performs.. well, performs normally poor. There are many contradicting requirements which are supposed to be met - and one can expect to fail on all of them. You cannot have the cake and eat it too; but it is easy to have no cake and still be hungry.