Has the flashing yellow left turn signal made it to your state?

[ARMOURERERIC]

Getting FY all over Morganton NC, but all the new state installations also are coming with a curved mast arm painted black and decorative pedesterian posts.  Really looks professional.  You can see them at the Enola Road and NC 18 exits of 40.  One thing I am seeing on NB Enola Road is FYL as part of a 3 lens setup, there is a dedicated left turn lane, but there is never a dedicated left phase.

[tradephoric]

I'm really not sure how I stand on this. On one hand, it makes sense. It's one thing to fail to yield to cars, but failing to yield to a pedestrian is almost always worse for the latter. On top of that, pedestrians are harder to spot than oncoming vehicles, and can sometimes be hidden behind a line of cars (at which point, the turning driver goes and, well, conflict!). On the other hand, it can potentially increase the amount of time that the signal is activated, because it has to let both the pedestrians and cars cross at separate intervals. It's one thing if there's a long line of oncoming cars, and you can't go anyways, but if there's no one coming, you feel like a sitting duck.

Drivers shouldn't be conditioned to believe pedestrians will be clear of the crosswalk when a permissive phase is displayed.  The fact is the compliance rate of pedestrians is abysmal and many will cross during the solid don't walk.  If an agency is so concerned with vehicle/ped conflicts they should make the left turn protected only.  Or just leave it as it is and allow permissive phasing with the walk.

[wxfree]

They're now in my area.  With the old signals, the usual progression was green arrow/green circle, yellow arrow/green circle, green circle.  A left turn could be made throughout that time if there was no traffic in the other direction.  Now it goes green arrow, yellow arrow, red arrow, flashing yellow arrow.  Now the opportunity to turn is broken for about a second.  It's not a big deal, and you can time your approach to get there after the flashing begins, but it's a little less efficient.  In concept, though, I like the flashing arrow better than the green circle for the "yield" instruction.

[vdeane]

I'm really not sure how I stand on this. On one hand, it makes sense. It's one thing to fail to yield to cars, but failing to yield to a pedestrian is almost always worse for the latter. On top of that, pedestrians are harder to spot than oncoming vehicles, and can sometimes be hidden behind a line of cars (at which point, the turning driver goes and, well, conflict!). On the other hand, it can potentially increase the amount of time that the signal is activated, because it has to let both the pedestrians and cars cross at separate intervals. It's one thing if there's a long line of oncoming cars, and you can't go anyways, but if there's no one coming, you feel like a sitting duck.

Drivers shouldn't be conditioned to believe pedestrians will be clear of the crosswalk when a permissive phase is displayed.  The fact is the compliance rate of pedestrians is abysmal and many will cross during the solid don't walk.  If an agency is so concerned with vehicle/ped conflicts they should make the left turn protected only.  Or just leave it as it is and allow permissive phasing with the walk.

I think the idea of eliminating permissive phases just because many drivers are too stupid to look for pedestrians is HORRIBLE.  Don't punish me because many people don't bother to look for anything but cars!

As for fostering the belief that pedestrians won't be around in permissive phases... you're trying to close the barn door after the horses are already long gone.

[jakeroot]

Now it goes green arrow, yellow arrow, red arrow, flashing yellow arrow.  Now the opportunity to turn is broken for about a second.  It's not a big deal, and you can time your approach to get there after the flashing begins, but it's a little less efficient.

Seattle has fixed this issue by dropping the interim red. You can read a little about it on the last page, but here's a video demonstrating how it works:

https://youtu.be/dmoD0aX4wJM

[jakeroot]

Drivers shouldn't be conditioned to believe pedestrians will be clear of the crosswalk when a permissive phase is displayed.  The fact is the compliance rate of pedestrians is abysmal and many will cross during the solid don't walk.  If an agency is so concerned with vehicle/ped conflicts they should make the left turn protected only.  Or just leave it as it is and allow permissive phasing with the walk.

I think the idea of eliminating permissive phases just because many drivers are too stupid to look for pedestrians is HORRIBLE.  Don't punish me because many people don't bother to look for anything but cars!...As for fostering the belief that pedestrians won't be around in permissive phases... you're trying to close the barn door after the horses are already long gone.

So what your both saying is, unless we can get rid of 100% of the problem, we shouldn't do anything? Entirely eliminating the permissive phase is not at all practical, but there are other steps that can be taken to protect at least some of the pedestrians. This includes red arrows when pedestrians are crossing. Short crossings are only around 15-20 seconds, and it lets through traffic proceed while they cross -- not that big of a deal. On top of that, the potential benefit to pedestrians is huge. We obviously can't protect everyone, but we can at least take some measures to be smart about it.

FWIW, I don't think this phasing would have been implemented if it wasn't at least partly effective.

[tradephoric]

So what your both saying is, unless we can get rid of 100% of the problem, we shouldn't do anything? Entirely eliminating the permissive phase is not at all practical, but there are other steps that can be taken to protect at least some of the pedestrians. This includes red arrows when pedestrians are crossing. Short crossings are only around 15-20 seconds, and it lets through traffic proceed while they cross -- not that big of a deal. On top of that, the potential benefit to pedestrians is huge. We obviously can't protect everyone, but we can at least take some measures to be smart about it.

I didn't say don't do anything.  I'm suggesting there are unintended consequences for disabling the flashing yellow arrow when a pedestrian call is placed.  And I'm not convinced it will be effective at reducing pedestrian injuries at FYA installations.  What happens when a pushbutton faults?  The signal will run protected only until someone gets out there to fix it.  I know government agencies are the poster child for efficiency, but still, it would be a big annoyance having the signal run protected only until the pushbutton is fixed.

[jakeroot]

I didn't say don't do anything.

Allow me to retort:

If an agency is so concerned with vehicle/ped conflicts they should make the left turn protected only.

I'm suggesting there are unintended consequences for disabling the flashing yellow arrow when a pedestrian call is placed.  And I'm not convinced it will be effective at reducing pedestrian injuries at FYA installations.  What happens when a pushbutton faults?  The signal will run protected only until someone gets out there to fix it.  I know government agencies are the poster child for efficiency, but still, it would be a big annoyance having the signal run protected only until the pushbutton is fixed.

Bellevue, WA adopted this system called "SCATS", which stands for "Sydney Coordinated Adaptive Traffic System", which uses a bunch of different things to determine when and when not to enabled the permissive phase (AFAICT, the system originated in Australia, and is used in both Australia and New Zealand). Evidently, there have not been any vehicle/pedestrian conflicts at intersections with "SCATS" phasing.

As I am not a traffic engineering expert, I'll let you read the Powerpoint: https://goo.gl/mWLcBd

As for a pushbutton fault? I think that's the least of Bellevue's concerns.

[cl94]

I think Trade is referring to phasing that eliminates the FY when the ped phase is active. If a person pushes the button, the FY phase could be disabled to increase pedestrian safety. I think this is a great idea and it goes along with how some places, notably some locations in NYSDOT Region 1, have blackout NTOR signs that are only lit when a ped phase at a conflicting crosswalk is active to protect pedestrians from idiots turning on red.

[vdeane]

Drivers shouldn't be conditioned to believe pedestrians will be clear of the crosswalk when a permissive phase is displayed.  The fact is the compliance rate of pedestrians is abysmal and many will cross during the solid don't walk.  If an agency is so concerned with vehicle/ped conflicts they should make the left turn protected only.  Or just leave it as it is and allow permissive phasing with the walk.

I think the idea of eliminating permissive phases just because many drivers are too stupid to look for pedestrians is HORRIBLE.  Don't punish me because many people don't bother to look for anything but cars!...As for fostering the belief that pedestrians won't be around in permissive phases... you're trying to close the barn door after the horses are already long gone.

So what your both saying is, unless we can get rid of 100% of the problem, we shouldn't do anything? Entirely eliminating the permissive phase is not at all practical, but there are other steps that can be taken to protect at least some of the pedestrians. This includes red arrows when pedestrians are crossing. Short crossings are only around 15-20 seconds, and it lets through traffic proceed while they cross -- not that big of a deal. On top of that, the potential benefit to pedestrians is huge. We obviously can't protect everyone, but we can at least take some measures to be smart about it.

FWIW, I don't think this phasing would have been implemented if it wasn't at least partly effective.

I think you misread my post.  I was responding to Mr. Parclo B4's assertion that we should eliminate all permissive left turns across the entire highways system because of the problem rather than just have the red arrow when pedestrians are crossing.

[tradephoric]

I think you misread my post.  I was responding to Mr. Parclo B4's assertion that we should eliminate all permissive left turns across the entire highways system because of the problem rather than just have the red arrow when pedestrians are crossing.

If drivers realize that the FYA is suppressed when a pedestrian actuates the pushbutton, then they may be more lax in scanning the intersection for pedestrians when encountering a FYA (since the FYA should be suppressed when a pedestrian is crossing).  The problem is so many pedestrians cross during the solid don't walk and there very well may be a pedestrian in the crosswalk.  IMO, suppressing the FYA is a dangerous precedent that Washington is starting.  The concern of a broken pushbutton hijacking the intersection shouldn't be taken lightly either.  Do you really want an intersection to run protected at 2 in the morning just because of a broken pushbutton?  Broken detection is more common then some may think.   

Ultimately, i want to see the study that indicates suppressing the FYA would be safer (real world numbers, not just simulation studies).  Until then, it's speculation that suppressing the FYA would be any safer.  So Vdeane, do you have a link to that study or are you just full of speculation (among other things)?

[cl94]

Then program it so it doesn't go full protected at night. We have that technology. The problem is that people treat permissives like protecteds if there is no conflicting car traffic in most parts of the country and people don't look for peds anyway. You wouldn't believe how often I get flipped off for crossing on a walk signal in these parts.

[tradephoric]

"The problem is that people treat permissives like protecteds if there is no conflicting car traffic in most parts of the country and people don't look for peds anyway."  

It's absolutely true that some drivers don't look for pedestrians inside the crosswalk at a permissive left.  In fact, in one simulation study 4-7% of drivers did not focus for pedestrians inside the crosswalk. 

Abstract
In some jurisdictions, protected left-turn phasing has been replaced with the flashing yellow arrow (FYA) for protected/permissive left turns (PPLTs) to reduce delay. However, it is important to have a thorough understanding of the conflict between pedestrians and the permissive left-turning vehicle.  This presentation summarizes the results of research conducted with a high-fidelity, motion-based driving simulator and mobile eye-tracking equipment to study the effects of the opposing traffic, the presence and walking direction of pedestrians, and the number of section heads to display the FYA on driver performance. To accomplish this research, a six-intersection simulated environment was created. In total, 27 subjects completed the course, allowing the analysis of 620 permissive left-turn maneuvers.  Eye-glance durations for the intersection approach and turning maneuver were captured for left-turn pavement bay markings, the signal indication, the pedestrian and vehicle waiting area, and the pedestrian signal heads. The total glance durations for each of these areas were analyzed. The following results were obtained: 1) the increased presence of pedestrians led drivers to focus more attention on these crossing pedestrians; 2) as the number of opposing vehicles increased, drivers spent less time fixating on pedestrians; 3) Four to seven percent of drivers did not focus on pedestrians in the crosswalk; and 4) there did not appear to be a difference between any variable and the presence of a three- or four-section head. In terms of practice, the results suggest that it may be desirable to limit the permissive operation when pedestrians are present. Moreover, the findings may indicate that the additional cost of four-section heads is not justified.
http://library.state.or.us/repository/2013/201304261019565/index.pdf

So a case can be made that the FYA should turn to protected only when a pedestrian is present (indicated by a pushbutton actuation).  But there are unintended consequences to this type of operation.  If drivers realize that no pedestrians should legally be in the crosswalk when encountering a FYA, they have less incentive to scan the intersection for pedestrians.  Instead of 4-7% of drivers not looking for pedestrians, the majority of drivers may stop looking for pedestrians at FYAs.  Seeing that so many pedestrians ignore the Solid Don't Walk indication, that is a dangerous situation since a pedestrian may very well be in the crosswalk.  The non-compliance rate of pedestrians is too high to make this type of operation effective IMO. 

Then program it so it doesn't go full protected at night. We have that technology.

But should a pedestrian crossing at night be less protected than a pedestrian crossing during the day?   You could argue that a pedestrian crossing at night is more vulnerable due to the reduced visibility.  Sure, it sucks when a faulty pushbutton causes the signal to run all night but that is the price you pay if you want to run this type of setup (the real solution is DON'T run this type of setup!).  Just causes too many problems and the potential safety benefits are questionable at best.  But good luck to Washington State for trying it.

[jeffandnicole]

How does a single study produce a range of 4-7%?  If it was one study, it should be one figure.

And a single simulation isn't a great indication of a study.  Good studies are done over the course of a period of time with many circumstances and groups of people.  It also depends on what other factors were in play.  It also doesn't indicate how many pedestrians, if any, got hit, or if the pedestrian had the right of way (did they enter during a "Don't Walk" phase, for example).

[tradephoric]

How does a single study produce a range of 4-7%?  If it was one study, it should be one figure.

I didn't read the entire 80 page study, but it appears they analyzed drivers focusing on pedestrians at a variety of traffic conditions (ie. "as the number of opposing vehicles increased, drivers spent less time fixating on pedestrians;" ).  So 7% of drivers failed to focus for pedestrians during heavy traffic and 4% failed to focus for pedestrians when opposing traffic was light.

And a single simulation isn't a great indication of a study.  Good studies are done over the course of a period of time with many circumstances and groups of people.  It also depends on what other factors were in play.  It also doesn't indicate how many pedestrians, if any, got hit, or if the pedestrian had the right of way (did they enter during a "Don't Walk" phase, for example).

The results of a simulation study aren't compelling enough for me either and I said so much previously ("Ultimately, i want to see the study that indicates suppressing the FYA would be safer (real world numbers, not just simulation studies)".   The simulation study is effective in showing that some drivers fail to look for pedestrians inside the crosswalk during a permissive left turn but it fails to tell you how unsafe this driving behavior would be in the real world (that's where the unintended consequences come into play).  I don't think Washington State should roll out these FYAs until some real world numbers come in that indicate they are indeed safer for pedestrians.

[jeffandnicole]

Wait..I read the original post wrong.  4-7% did NOT focus on the pedestrians?  I was reading it as only 4-7% focused on the pedestrians.

While you would want 100% of traffic to focus on everything at all times, if only 5% didn't focus on the pedestrians in a simulation study, that's really not all that bad.  And it would be interesting to see what the comparison is to other traffic signals and devices (stop signs, yielding on green ball, etc).

The only thing to make it perfectly safe for pedestrians is bridges or tunnels.  And even that isn't going to be 100% effective.  There's still those that run across the road for no reason.  And if there is a car accident, if a person exits their car and gets hit and killed, that fatality is considered a pedestrian fatality.

[jakeroot]

I don't think Washington State should roll out these FYAs until some real world numbers come in that indicate they are indeed safer for pedestrians.

By all accounts, Bellevue, WA's rollout is a study of their effectiveness. If they don't work, they'll rip them out (err, disable the phasing). If they do, they'll keep them.

When I was up in Bellevue today, I noticed that some of the FYA's gave the crosswalk the walk sign before the FYA was turned on, so that pedestrians were well into the crosswalk before drivers could proceed (to make it plain, not all of Bellevue's FYA's have 24/7/365 "ped minus left" phasing -- the only signals that have them, were ones that were previously protected only, and they're only enabled during peak hours). I've seen this phasing a lot in Downtown Seattle, and other cities across the US (pedestrian pre-emption or something like that).

[tradephoric]

By all accounts, Bellevue, WA's rollout is a study of their effectiveness. If they don't work, they'll rip them out (err, disable the phasing). If they do, they'll keep them.

IMO, two things are needed for them to be effective:

1). Pedestrian detection (ie. Pushbuttons) so the controller knows when to suppress the FYA.
2). A high pedestrian compliance rate.

I'm sure the traffic engineers in Bellevue have good intentions but IMO they are making the intersections less pedestrian friendly by installing pushbuttons everywhere.  Here's a study out of Florida that looks at the compliance rate of pedestrians based on various walk modes (Intersection A & B don't require pushbutton use; Intersection C & D requires pushbutton use). 


http://scholarcommons.usf.edu/cgi/viewcontent.cgi?article=6025&context=etd

The intersections that required pushbutton use had abysmal pedestrian compliance rates.  A 91% non-compliance rate is a total failure.  Why even bother suppressing the FYA when the pedestrian compliance rate is so bad? 

[jakeroot]

By all accounts, Bellevue, WA's rollout is a study of their effectiveness. If they don't work, they'll rip them out (err, disable the phasing). If they do, they'll keep them.

IMO, two things are needed for them to be effective:

1). Pedestrian detection (ie. Pushbuttons) so the controller knows when to suppress the FYA.
2). A high pedestrian compliance rate.

I'm sure the traffic engineers in Bellevue have good intentions but IMO they are making the intersections less pedestrian friendly by installing pushbuttons everywhere.  Here's a study out of Florida that looks at the compliance rate of pedestrians based on various walk modes (Intersection A & B don't require pushbutton use; Intersection C & D requires pushbutton use). 
...

The intersections that required pushbutton use had abysmal pedestrian compliance rates.  A 91% non-compliance rate is a total failure.  Why even bother suppressing the FYA when the pedestrian compliance rate is so bad? 

I'd have to see some numbers, but I think it's fair to say that some parts of the country have higher compliance rates than others. Having driven through Bellevue on numerous occasions, while there are jaywalkers, I don't necessarily think it's a widespread problem.

I could be wrong, but don't adaptive traffic systems require pushbuttons? Crossings without pushbuttons are timed, yes? Timed intersections are really quite rare around here, outside of the city centers. Downtown Bellevue has some, but Downtown Bellevue also has a lot of protected-only left turns in the pedestrian-heavy areas.

[tradephoric]

I could be wrong, but don't adaptive traffic systems require pushbuttons? Crossings without pushbuttons are timed, yes? Timed intersections are really quite rare around here, outside of the city centers. Downtown Bellevue has some, but Downtown Bellevue also has a lot of protected-only left turns in the pedestrian-heavy areas.

Adaptive systems don't require pushbuttons.  Deciding whether or not to install a pushbutton at a particular intersection isn't dependent on if the signal will be running adaptively.  Now it's true that without pushbuttons you are limited to how "adaptive"  the signal can run but common sense should be used.  For instance if the required main-street pedestrian phase is only 15 seconds you probably don't need main-street pushbuttons.

[tradephoric]

I think you misread my post.  I was responding to Mr. Parclo B4's assertion that we should eliminate all permissive left turns across the entire highways system because of the problem rather than just have the red arrow when pedestrians are crossing.

Vdeane, I don't want to eliminate all permissive left turns across the entire highway system.   Why would you even suggest that?   But I can't stop how the city of Bellevue wants to manages their traffic signals.   If they want to make every traffic signal in the city protected only then go for it.  They can do whatever the hell they want.

Drivers shouldn't be conditioned to believe pedestrians will be clear of the crosswalk when a permissive phase is displayed.  The fact is the compliance rate of pedestrians is abysmal and many will cross during the solid don't walk.  If an agency is so concerned with vehicle/ped conflicts they should make the left turn protected only.  Or just leave it as it is and allow permissive phasing with the walk.

Now if I was so opposed to permissive left turns why would I suggest they allow permissive phasing when a walk is displayed to the pedestrian?  That's more aggressive than what some here are proposing (ie. running a solid red arrow when the walk is on; permissive otherwise).

[jeffandnicole]

I could be wrong, but don't adaptive traffic systems require pushbuttons? Crossings without pushbuttons are timed, yes? Timed intersections are really quite rare around here, outside of the city centers. Downtown Bellevue has some, but Downtown Bellevue also has a lot of protected-only left turns in the pedestrian-heavy areas.

Adaptive systems don’t require pushbuttons.  Deciding whether or not to install a pushbutton at a particular intersection isn’t dependent on if the signal will be running adaptively.  Now it’s true that without pushbuttons you are limited to how “adaptive” the signal can run but common sense should be used.  For instance if the required main-street pedestrian phase is only 15 seconds you probably don't need main-street pushbuttons.

Doesn't work.  An adaptive system must detect both vehicles and pedestrians.  Otherwise, you will have timed systems.   The light will need to cycle every so often, 24 hours a day, if there's no pedestrian push button available.

Even if a 'pedestrian' phase is 15 seconds (which would only work if the cross street is a 2 lane roadway w/o shoulders), a car phase can be completed in half that time.  No sense having an extra 8 seconds of nothing going on if no pedestrians are present.   And you're not going to find crosswalks short enough to complete a ped phase in 15 seconds in most areas where adaptive systems are utilized. 

[tradephoric]

Doesn't work.  An adaptive system must detect both vehicles and pedestrians.  Otherwise, you will have timed systems.   The light will need to cycle every so often, 24 hours a day, if there's no pedestrian push button available.

A signal that constantly cycles can still run adaptively.  Adaptive operation simply adjusts the signal splits based on the traffic volumes present on a cycle-by-cycle basis.  Yes, it's sometimes nice to have side-street pushbuttons so a signal can rest in main-street green, but it's not a prerequisite for adaptive operation.

Even if a 'pedestrian' phase is 15 seconds (which would only work if the cross street is a 2 lane roadway w/o shoulders), a car phase can be completed in half that time.  No sense having an extra 8 seconds of nothing going on if no pedestrians are present.   And you're not going to find crosswalks short enough to complete a ped phase in 15 seconds in most areas where adaptive systems are utilized. 

Ok, but how often do you want your main drag to run 15 seconds?  I'm distinguishing between main-street and side-street pedestrian crossings because the distinction is important.  Sure, you may want to run your side-street less than 15 seconds but you rarely if ever would want to run your main-street that short.

[tradephoric]

Here's an intersection at 4th & 108th in Bellevue, Washington.   The intersection has pushbuttons at all 4 corners of the intersection.  I have no idea if this signal runs adaptively (and it's meaningless to the discussion) but it seems silly to have pushbuttons when this much pedestrian traffic is present.  Based on the high amount of pedestrian traffic the pushbutton will be pushed nearly every cycle anyways so why even bother with the pushbuttons?   Looking around Bellevue on streetview they have an overabundance of pushbuttons!

[jeffandnicole]

Here’s an intersection at 4th & 108th in Bellevue, Washington.   The intersection has pushbuttons at all 4 corners of the intersection.  I have no idea if this signal runs adaptively (and it’s meaningless to the discussion) but it seems silly to have pushbuttons when this much pedestrian traffic is present.  Based on the high amount of pedestrian traffic the pushbutton will be pushed nearly every cycle anyways so why even bother with the pushbuttons?   Looking around Bellevue on streetview they have an overabundance of pushbuttons!

Really?  Your entire argument that pushbuttons aren't needed is based on the one moment in time a Streetview camera passes by? 

Here's the aerial view.  Where's all the pedestrians?  https://goo.gl/maps/CKMAJUQHXwt

Here's the view on 4th Street.  I can count 6 pedestrians total. https://goo.gl/maps/8qK3Ko7BRK52

Here's the same exact view you presented...one year earlier: https://goo.gl/maps/PDGBAcpjzjT2

Another view, from 2008: https://goo.gl/maps/6W2UUDHC7Lv

What a fricken joke.  This more than anything shows and proves you cherrypick data and information to present information in a misleading manner.   Yes, pushbuttons are perfectly fine, because obviously the intersection isn't always going to have dozens of people, and probably for a good portion of the night and weekends, none at all.