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

Started by NJRoadfan, June 17, 2010, 10:58:35 AM

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roadfro

Quote from: Troubleshooter on July 28, 2010, 09:22:47 PM
Quote from: froggie on June 28, 2010, 06:17:31 PM
QuoteI always assumed FYA was to replace the flashing red ball and other divergent left turn signals (non-standard) in place in many states.  The tower or doghouse (depending on state) is not affected from what I can see as that has separate green and yellow arrows for a protected left and already provides for a permitted left.
Replacing the flashing red ball (or in Delaware and Maryland the flashing red arrow) is an ancillary effect.  But the primary reason for the FYA's development and purpose is because too many drivers were confusing the steady green (i.e. the permitted left) on the tower or the doghouse signals for a protected left.
Wrong. The purpose is to eliminate yellow trap without placing restrictions on signal phasing.

The implementation of the Flashing Yellow Arrow display resulted in a number of problems and concerns being addressed. The main impetus behind it, though, was the concern many engineers had with drivers mistakenly interpreting the circular green of a 5-section signal face as a protected left when the signal is intending a permitted left. Other "divergent" left turn signals and methods of displaying permitted left turns were studied, and the FYA method used in Reno (at the time...Reno has no FYA installations currently) was found to have the greatest driver understanding. Since the permissive left was indicated by an arrow instead of circular green, it allowed permitted left turns to proceed even while the adjacent through traffic displayed a red.

A side benefit to FYA signals is that the overlap of the FYA with the opposing through vehicle green eliminates the yellow trap a 5-section display would create (without Dallas Phasing) on the lagging left turn at a lead-lag signal. Another side benefit was the ease of switching between protected-only, protected-permitted, and permitted-only modes without having to design special controller logic to make a typical 5-section display have the same functionality (as Vegas had done at many intersections).


Knowing Reno and the lack of signal coordination/progression that the area had up until about 5 or so years ago (well after all the old FYA signals were removed), I'm fairly confident that there were few (if any) FYA installations running lead-lag at the time. Thus, the side benefits of eliminating yellow trap were likely not realized in those original implementations.

Quote from: Troubleshooter on July 30, 2010, 12:03:07 AM
It is the need to have a signal indication that allows a permissive turn to filter through gaps in oncoming traffic when the straight-ahead signals are red. And there are reasons other than yellow trap to use it.

What do you do if the following happens? (I have seen it)
- You are waiting in the intersection to turn left into a single lane side road.
- Your signal turns yellow, then red. But oncoming traffic still has a green, because the signal skipped the side street phase.
- During the oncoming green, the oncoming right turns have a green arrow. Even if the straight ahead stream has a gap in it, the right turners are blocking your turn. The oncoming right turn stream has very heavy traffic.
- The signal changes to the side street on your left having a green and a left turn green arrow. The oncoming right turn arrow is still green. So your turn is still blocked, and traffic from the left is honking for you to get out of the way.

This is not an intended sequence, but it is the sequence I have seen at a nearby shopping center at night, when some approaches are empty. The signal has split lead left turns and doghouse signals. But phase skip brings up such sequences.

Firstly, if the side street phase was skipped the first time around, the signal in my direction of travel should not have turned red.
Secondly, if there's a protected right turn opposite to my left turn, good signal design should require that my left turn would be prevented when that right turn is activated--meaning that I should have a red arrow during the opposing right turn green arrow.
Although, I'm having trouble figuring out why there'd be a protected right turn on the opposite approach that's feeding into a single-lane side road...

Quote
Here is another case:
- You are at a split intersection with a railroad running across the middle and two sets of signals, one on each side of the railroad track.
- You are waiting in the second intersection to turn left. There is no left turn signal at your intersection. But the first intersection (behind you) has a left turn doghouse signal facing in the opposite direction.
- The signal changes from straight ahead in both directions to the left turn for the other direction. Your signal turns red. There are three cars waiting behind you to turn. One is stupidly waiting on the tracks. But the oncoming signal is still green.
- The third car waiting in line is blocking the left turning cars from turning on the green arrow. They move forward, and are blocked. And again, one driver stops on the tracks. Now the two lines are blocking each other.
- A train comes. The signal goes into track clearance. But because your signal was already red, it does not attempt to clear the track in your direction. And the cars facing the other way are still blocked.
I saw this actually happen. Two left turners in each direction went straight ahead to clear the tracks. Two of them ran the red light to do so.

It's not clear to me whether this scenario is trying to depict a single intersection split by railroad tracks, or two separate intersections on either side of the tracks (got a specific example?). Each case has it's own operational challenges. In either case, when the signals go into preemption mode, the second set of signals on the main road should be set to go green immediately in order to clear any vehicles that could be caught between signals. Depending on spacing of signals, they should probably be programmed to not allow vehicles to be stopped in the middle in the first place. It also seems likely that such an intersection(s) shouldn't have permitted left turn phasing to begin with, due to the railroad tracks.
Roadfro - AARoads Pacific Southwest moderator since 2010, Nevada roadgeek since 1983.


vdeane

I don't think I've ever seen a traffic light skip a phase other than a protected turn, nor an intersection split by railroad tracks.
Please note: All comments here represent my own personal opinion and do not reflect the official position of NYSDOT or its affiliates.

Brandon

Quote from: deanej on July 30, 2010, 05:25:48 PM
I don't think I've ever seen a traffic light skip a phase other than a protected turn, nor an intersection split by railroad tracks.

You need to visit Illinois, specifically Chicagoland more often.  We have a ton of intersections split by railroad tracks, and a bunch that have the tracks crossing directly through the middle of them.
"If you think this has a happy ending, you haven't been paying attention." - Ramsay Bolton

"Symbolic of his struggle against reality." - Reg

NJRoadfan

Quote from: Troubleshooter on July 28, 2010, 09:19:44 PM
Indiana doesn't have it yet, because some legislators are afraid of it.

I have kept a running list of who has and who doesn't:

HAS:

AK AL AR AZ CA CO CT DC DE FL GA IA ID IL KS KY LA MD ME MI MN MO MS MT NC NH NJ NM NV NY OR SC TX UT VA VT WA WI WY Territories GU

HAS NOT:

HI IN MA ND NE OH OK PA RI SD TN WV Territories PR VI

Add NJ to the HAS NOT list, apparently they have not gotten Intern Approval. This should be a somewhat up to date list of who actually has these signals.

http://mutcd.fhwa.dot.gov/resources/interim_approval/ialistreq.htm

(search for "IA-10")

MichiganDriver

Quote from: NJRoadfan on August 01, 2010, 01:29:40 AM
Quote from: Troubleshooter on July 28, 2010, 09:19:44 PM
Indiana doesn't have it yet, because some legislators are afraid of it.

I have kept a running list of who has and who doesn't:

HAS:

AK AL AR AZ CA CO CT DC DE FL GA IA ID IL KS KY LA MD ME MI MN MO MS MT NC NH NJ NM NV NY OR SC TX UT VA VT WA WI WY Territories GU

HAS NOT:

HI IN MA ND NE OH OK PA RI SD TN WV Territories PR VI

Add NJ to the HAS NOT list, apparently they have not gotten Intern Approval. This should be a somewhat up to date list of who actually has these signals.

http://mutcd.fhwa.dot.gov/resources/interim_approval/ialistreq.htm

(search for "IA-10")


Please note that Interim Approvals IA-1, IA-2, IA-4R, IA-8, IA-9, and IA-10 have been terminated because the devices involved have been incorporated into the 2009 MUTCD.

Troubleshooter

Quote from: Scott5114 on July 30, 2010, 02:19:01 AM
Quote from: Troubleshooter on July 30, 2010, 12:03:07 AM
I know how to use the edit button. Did I miss a typo?

You posted five and then seven times in a row. If you forget something, use the edit button to go back and add something. If you want to quote multiple people, click the "Reply" tab at the bottom–don't use the Quick Reply box–and use the "Insert Quote" feature next to each post you want to quote.

That's how another BBS I use wants me to do it. They don't like me including several different replies from different posters in the same post.

I am going to keep doing that, because I can't keep track of which BBS prefers what. I use about 20 different BBS systems, and this is the only one that seems to want reply posts combined.

Also note that those replies were posted at different times. I was returning to the BBS between bursts of taking care of other business (e.g. phone calls). All of the other BBS systems I use close the post to further editing after 15 minutes.

US71

TS: there is also a "modify" button if you want to go back and revise or supplement what you've already posted.
Like Alice I Try To Believe Three Impossible Things Before Breakfast

Troubleshooter

#107
Quote from: roadfro on July 30, 2010, 03:34:04 AM
Quote from: Troubleshooter on July 28, 2010, 09:22:47 PM
Quote from: froggie on June 28, 2010, 06:17:31 PM
QuoteI always assumed FYA was to replace the flashing red ball and other divergent left turn signals (non-standard) in place in many states.  The tower or doghouse (depending on state) is not affected from what I can see as that has separate green and yellow arrows for a protected left and already provides for a permitted left.
Replacing the flashing red ball (or in Delaware and Maryland the flashing red arrow) is an ancillary effect.  But the primary reason for the FYA's development and purpose is because too many drivers were confusing the steady green (i.e. the permitted left) on the tower or the doghouse signals for a protected left.
Wrong. The purpose is to eliminate yellow trap without placing restrictions on signal phasing.
The implementation of the Flashing Yellow Arrow display resulted in a number of problems and concerns being addressed. The main impetus behind it, though, was the concern many engineers had with drivers mistakenly interpreting the circular green of a 5-section signal face as a protected left when the signal is intending a permitted left. Other "divergent" left turn signals and methods of displaying permitted left turns were studied, and the FYA method used in Reno (at the time...Reno has no FYA installations currently) was found to have the greatest driver understanding. Since the permissive left was indicated by an arrow instead of circular green, it allowed permitted left turns to proceed even while the adjacent through traffic displayed a red.

This was the reason behind the Reno signals, but not the reason behind the Michigan flashing red ball, the Seattle flashing yellow ball, or Dallas phasing. They were trying to remove yellow trap. The purpose of the Kittleson study was also to remove yellow trap, not to remove driver confusion.

Also, the original Reno implementation could not prevent yellow trap. It was just the source of the idea of using a flashing yellow arrow to prevent yellow trap.

Note that what some engineers thought was driver confusion was actually yellow trap. So they went about solving it the wrong way.

Quote
Quote from: Troubleshooter on July 30, 2010, 12:03:07 AM
It is the need to have a signal indication that allows a permissive turn to filter through gaps in oncoming traffic when the straight-ahead signals are red. And there are reasons other than yellow trap to use it.

What do you do if the following happens? (I have seen it)
- You are waiting in the intersection to turn left into a single lane side road.
- Your signal turns yellow, then red. But oncoming traffic still has a green, because the signal skipped the side street phase.
- During the oncoming green, the oncoming right turns have a green arrow. Even if the straight ahead stream has a gap in it, the right turners are blocking your turn. The oncoming right turn stream has very heavy traffic.
- The signal changes to the side street on your left having a green and a left turn green arrow. The oncoming right turn arrow is still green. So your turn is still blocked, and traffic from the left is honking for you to get out of the way.

This is not an intended sequence, but it is the sequence I have seen at a nearby shopping center at night, when some approaches are empty. The signal has split lead left turns and doghouse signals. But phase skip brings up such sequences.

Firstly, if the side street phase was skipped the first time around, the signal in my direction of travel should not have turned red.

But it does so anyway, if the controller is not modified to specifically prevent it. Most of the signals in my area do this.

QuoteSecondly, if there's a protected right turn opposite to my left turn, good signal design should require that my left turn would be prevented when that right turn is activated--meaning that I should have a red arrow during the opposing right turn green arrow.
Although, I'm having trouble figuring out why there'd be a protected right turn on the opposite approach that's feeding into a single-lane side road...

This is an actual intersection near me. The protected right turn was installed to clear out heavy right turn traffic during the equally heavy left turn traffic that overlaps it. But whoever programmed the signal sequence put an overlap on that right turn to overlap the straight ahead phase. Note that much of the signal "design" in my area is actually done by politicians, who override the decisions of engineers, because they want something else.

Quote
Quote
Here is another case:
- You are at a split intersection with a railroad running across the middle and two sets of signals, one on each side of the railroad track.
- You are waiting in the second intersection to turn left. There is no left turn signal at your intersection. But the first intersection (behind you) has a left turn doghouse signal facing in the opposite direction.
- The signal changes from straight ahead in both directions to the left turn for the other direction. Your signal turns red. There are three cars waiting behind you to turn. One is stupidly waiting on the tracks. But the oncoming signal is still green.
- The third car waiting in line is blocking the left turning cars from turning on the green arrow. They move forward, and are blocked. And again, one driver stops on the tracks. Now the two lines are blocking each other.
- A train comes. The signal goes into track clearance. But because your signal was already red, it does not attempt to clear the track in your direction. And the cars facing the other way are still blocked.
I saw this actually happen. Two left turners in each direction went straight ahead to clear the tracks. Two of them ran the red light to do so.

It's not clear to me whether this scenario is trying to depict a single intersection split by railroad tracks, or two separate intersections on either side of the tracks (got a specific example?). Each case has it's own operational challenges. In either case, when the signals go into preemption mode, the second set of signals on the main road should be set to go green immediately in order to clear any vehicles that could be caught between signals. Depending on spacing of signals, they should probably be programmed to not allow vehicles to be stopped in the middle in the first place. It also seems likely that such an intersection(s) shouldn't have permitted left turn phasing to begin with, due to the railroad tracks.

Here is the intersection pair.

http://maps.google.com/?ie=UTF8&ll=39.1564,-86.582528&spn=0.001163,0.002068&t=k&z=19

- The road on the right is a driveway to a very large factory.

- The signals beyond the tracks are visibility limited.

- Notice that there is no left turn lane for southbound traffic.

- A driver turning into the factory can be trapped if the side street phases are skipped and the northbound left turn is called.

- The event listed above happened when people were arriving for work at the start of the first shift.

- There is also a school down the road to the left with employees arriving at the same time.

- During railroad preemption hold, both side streets get left turn arrows for the duration. Turns on red are prohibited in all directions.

I told the engineer that yellow trap was happening, but he is one of those people who thinks that the normal left turn right of way law is enough, and that people "need to watch traffic before turning."


rickmastfan67

Quote from: Troubleshooter on August 02, 2010, 12:33:54 AM
Also note that those replies were posted at different times. I was returning to the BBS between bursts of taking care of other business (e.g. phone calls). All of the other BBS systems I use close the post to further editing after 15 minutes.

Well, here at this site, you can edit your post 5 years after you make it if you feel like it.  There are no time restrictions.

Troubleshooter

#109
Quote from: NJRoadfan on August 01, 2010, 01:29:40 AM
Quote from: Troubleshooter on July 28, 2010, 09:19:44 PM
Indiana doesn't have it yet, because some legislators are afraid of it.

I have kept a running list of who has and who doesn't:

HAS:

AK AL AR AZ CA CO CT DC DE FL GA IA ID IL KS KY LA MD ME MI MN MO MS MT NC NH NJ NM NV NY OR SC TX UT VA VT WA WI WY Territories GU

HAS NOT:

HI IN MA ND NE OH OK PA RI SD TN WV Territories PR VI

Add NJ to the HAS NOT list, apparently they have not gotten Intern Approval. This should be a somewhat up to date list of who actually has these signals.

http://mutcd.fhwa.dot.gov/resources/interim_approval/ialistreq.htm

(search for "IA-10")

There is no interim approval any more. FYA is part of the MUTCD now!

One NJ community (downstate) has one signal. I can't find the news release on it anymore, because some newspapers either don't put archived stories on the Internet, or charge for accessing them. The link I saved now goes to a story on pet dogs.

Scott5114

Quote from: Troubleshooter on August 02, 2010, 12:33:54 AM
Quote from: Scott5114 on July 30, 2010, 02:19:01 AM
Quote from: Troubleshooter on July 30, 2010, 12:03:07 AM
I know how to use the edit button. Did I miss a typo?

You posted five and then seven times in a row. If you forget something, use the edit button to go back and add something. If you want to quote multiple people, click the "Reply" tab at the bottom–don't use the Quick Reply box–and use the "Insert Quote" feature next to each post you want to quote.

That's how another BBS I use wants me to do it. They don't like me including several different replies from different posters in the same post.

I am going to keep doing that

You are not.
uncontrollable freak sardine salad chef

Troubleshooter

#111
Quote from: Scott5114 on August 02, 2010, 12:21:59 PM
Quote from: Troubleshooter on August 02, 2010, 12:33:54 AM
Quote from: Scott5114 on July 30, 2010, 02:19:01 AM
Quote from: Troubleshooter on July 30, 2010, 12:03:07 AM
I know how to use the edit button. Did I miss a typo?

You posted five and then seven times in a row. If you forget something, use the edit button to go back and add something. If you want to quote multiple people, click the "Reply" tab at the bottom—don't use the Quick Reply box—and use the "Insert Quote" feature next to each post you want to quote.

That's how another BBS I use wants me to do it. They don't like me including several different replies from different posters in the same post.

I am going to keep doing that

You are not.

I am not "forgetting things"

I am posting at different times as I read on in the topic, and see something else that I want to reply to. These are totally different thoughts, not connected to each other, that happen at different times. So the use of the reply button instead of the quick reply makes no sense at all. By the time I see that I want to make the second reply, the first one is already forgotten.

I now know what to do, but your instructions on how to do it made no sense. The modify button does not let me add a quoted post with the author included, and the reply button won't let me edit the post I already saved.

Here is the procedure I am now using, so I don't lose the author of the post:

1. Click quick reply. If it is the first post in the topic, go ahead and make it.
2. If it is a subsequent reply, copy the quoted text into the clipboard instead of posting.
3. Modify the first post I made, and paste the clipboard contents at the bottom.
4. Add my reply after that, and save the edit.

Is this right????? It's complicated.

You have some weird rules here. At every other BBS, I would be kicked off for doing that. Plus, it would usually violate the 15 minute timeout on one page, and I get logged off.

agentsteel53

#112
Quote from: Troubleshooter on August 04, 2010, 01:48:22 AM
Is this right????? It's complicated.

I think that when the initial frenzy wears off, there will be a much diminished set of posts that you will want to reply to.  Two or three posts in a row is okay - five or six is a bit excessive.

QuoteYou have some weird rules here. At every other BBS, I would be kicked off for doing that. Plus, it would usually violate the 15 minute timeout on one page, and I get logged off.

we sure as Hell don't have such idiocy as a "15 minute timeout".  Your cookie expires in 2037.  None of that lunacy of making you redo everything just because the server thought you were a security threat.  (See: eBay and their idiocy.)
live from sunny San Diego.

http://shields.aaroads.com

jake@aaroads.com

Tarkus

Never seen a 15 minute time out on edits here, either.

Anyway, back on topic, the 3-light multimode FYAs have been popping up like crazy in Oregon as of late, and they seem to be becoming the preferred design now, at least in Washington County.  Noticed 3 new ones in Hillsboro the other day.

-Alex (Tarkus)

Scott5114

Okay, this is the simplest way to insert multiple quotes:

Don't touch the "Quick Reply" box. Click the "Reply" tab at the bottom of the page FIRST. (If you're still reading the thread for stuff to reply to bring it up in a new tab to make it easier if you like.) When you see something you want to quote, click the "Insert Quote" link on the post you want to quote. That will insert it in the box where you can type under it to your heart's content. To insert the next quote click the "Insert Quote" link on the post you want to quote. That will insert it in the box where you can type under it to your heart's content. Ad nauseum.

This is not a BBS. This is a forum. There is a significant difference. BBSes died around 1998, for one. You will need to adapt your posting habits to the new environment, or the environment will...not react well.
uncontrollable freak sardine salad chef

FreewayDan

Flashing yellow left turn signals are now in the Houston area.  Sugar Land is the first in the area with FYAs installed at five intersections:

http://www.fortbendnow.com/2010/04/16/45180
LEFT ON GREEN
ARROW ONLY

MichiganDriver

Which states are putting these in the quickest? I know Oregon and Michigan have committed to systematic replacement. But what about other states?


US71

Quote from: MichiganDriver on August 22, 2010, 09:24:04 AM
Which states are putting these in the quickest? I know Oregon and Michigan have committed to systematic replacement. But what about other states?


Not Arkansas. Most cities say they don't want them. Fort Smith started with around 20 of them 3 years ago, but they have expanded upon it since. Several intersections have been upgraded to FYA's and most new signals are FYA's, where there is a multi-phase left turn signal.
Like Alice I Try To Believe Three Impossible Things Before Breakfast

74/171FAN

I am now a PennDOT employee.  My opinions/views do not necessarily reflect the opinions/views of PennDOT.

74/171FAN

Virginia Tech, where I currently attend, is now getting a couple on Southgate Drive.
I am now a PennDOT employee.  My opinions/views do not necessarily reflect the opinions/views of PennDOT.

Tom

Yes, there are some flashing yellow arrows in Michigan, but for those who prefer the left turn green arrows, they are still around in Michigan. :coffee:

Coelacanth

Quote from: froggie on June 17, 2010, 02:43:07 PM
Minnesota only has one that I'm aware of, at MN 110/MN 149.
Well this thread has wandered around a bit, but I just thought I'd point out that there is one of these signals on CSAH 9 at Nevada Avenue in New Hope. I think there are actually a couple of them along CSAH 9 (42nd Ave/Rockford Road) between TH 100 and I-494, but the one at Nevada is the only one that I've definitely seen with the flashing yellow.

froggie

Doesn't surprise me.  As I understand it, MnDOT recently changed their policy to where all new traffic signal installations that normally would have gotten a protected-permitted signal will get the FYA instead.  Presumably, this will include installations funded via state aid.  Existing signals will only be retrofitted "when necessary"...or probably when the signal comes up for normal replacement.

Bickendan

Quote from: Tarkus on August 04, 2010, 02:38:01 AM
Anyway, back on topic, the 3-light multimode FYAs have been popping up like crazy in Oregon as of late, and they seem to be becoming the preferred design now, at least in Washington County.  Noticed 3 new ones in Hillsboro the other day.

-Alex (Tarkus)
Gresham has about five sets on Powell alone.

froggie

Earlier in the thread it was mentioned where a few FYA installations in North Carolina were.  While in the state over this past weekend, I found three more:  a relatively new installation at NC 68/NC 150 in Oak Ridge, and two along US 70 outside Pine Level.



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