Use of red arrows for protected turns

[Ian]

 :wow:10 page?? jeeze  :no:not cool

[yanksfan6129]

Its not huge compared to college research papers, but for now . . .

[Ian]

oh boy i cant wait 

[vdeane]

Agree that New York is not uniform.  But in my experience (mostly Upstate and the Hudson Valley), protected left turns using a standard red ball instead of a red arrow are the exception instead of the norm.

Here in Rochester you mainly see the "doghouse" style.

[FreewayDan]

Some Texas cities use red arrows for protected turns:

Beaumont
Lubbock
Dallas
Waco area
Pasadena (double red arrow)

[The High Plains Traveler]

OK - take that one step further. What states are using the part-time protected only turn, with a flashing yellow arrow during off-peak periods allowing a permissive left? In Colorado along CDOT-maintained routes, Pueblo seems to be the primary place where they are being evaluated. FYI, they are not used when there are multiple turn lanes; protected-only turns are indicated for that situation.

[PAHighways]

I haven't seen any flashing yellow arrows in Pennsylvania.  They aren't even mentioned as being used in other states in the Driver's Manual.

[Revive 755]

OK - take that one step further. What states are using the part-time protected only turn, with a flashing yellow arrow during off-peak periods allowing a permissive left? In Colorado along CDOT-maintained routes, Pueblo seems to be the primary place where they are being evaluated. FYI, they are not used when there are multiple turn lanes; protected-only turns are indicated for that situation.

MoDOT was trying some on MO 340 west of I-270:
http://maps.google.com/maps?hl=en&ie=UTF8&ll=38.678194,-90.468764&spn=0,359.994507&z=18&layer=c&cbll=38.67813,-90.468611&panoid=2zjqK4MQ13mBQ6Woufrzjw&cbp=12,281.7514931313731,,0,6.7578125

I believe there are supposed to be more in Missouri for new/replacement signal installations in the future.

I don't think the flashing yellow arrow is a good idea, at least in Missouri, where flashing yellow is used for inactive signals - such as fire station signals on state roads, or many signals during the late night/early morning hours.  I also cannot recall ever seeing anyone fail to understand "left turn yield on [green ball]," so I have doubts about the need for it.

EDIT:  MoDOT site on the flashing yellow left turn arrows for reference:
http://www.modot.org/stlouis/links/flashingyellowarrows.htm

[Bryant5493]

green ball]," so I have doubts about the need for it.

EDIT:  MoDOT site on the flashing yellow left turn arrows for reference:
http://www.modot.org/stlouis/links/flashingyellowarrows.htm

I can see MoDOT's reasoning for the flashing yellow light, but I'm with you, the green ball and a sign re-enforcing the fact "left turn yield on green" would be prudent enough. Flashing lights, I think, will "confuse" folks even more.


Be well,

Bryant

[Bryant5493]

The first intersection, located on the southside of College Park (GA), has a green protected arrow and a green, yellow and red ball. The intersecting roads are Godby Road and <-- Norman Boulevard/Southampton Road -->.

The second intersection, located in Lawrenceville (GA), along SR 316 (University Parkway) at SR 20/124 (Buford Drive), uses double red arrows for protected left turns.


Be well,

Bryant

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[leonontheroad]

What about double red ball left turn indicators? The only place I've seen these are in Houston.

San Diego seems to be pretty consistent with the red left-turn arrows.

I was in Burlington, ON and I noticed the green left turn indicators blinked. Or it was the yellow, can't exactly remember.

[Ian]

mmmmmmmmmmmmmmmmm traaaffiic siiiiiiiignaaaaaaals 

[Ian]

Some of the left turn signals in New York look like these:
http://picasaweb.google.com/Iansignal/NewYorkTrafficSignalsAndRoadSigns#5289469382366653250

[Bryant5493]

Some of the left turn signals in New York look like these:
http://picasaweb.google.com/Iansignal/NewYorkTrafficSignalsAndRoadSigns#5289469382366653250

I've noticed some like that in Gwinnett and Hall counties, Georgia. It's odd to see a traffic light hanging by a long wire like that, along with the lane assignment signs.


Be well,

Bryant

[Revive 755]

What about double red ball left turn indicators? The only place I've seen these are in Houston.

I think North Carolina had a lot of them in the past, but I can't find any on streetview today, only red arrows and dog house setups.  I referred to them as bug-eyed or insectesoid lights due to their setup:

                              R  R
                                Y
                                G
(can't remember if they were arrow or ball-shaped for the yellow and green)

[FreewayDan]

What about double red ball left turn indicators? The only place I've seen these are in Houston.

On Google Streets, I've seen double red ball turn signals in Dallas, Austin, Laredo and San Angelo.

[Alex]

What about double red ball left turn indicators? The only place I've seen these are in Houston.

On Google Streets, I've seen double red ball turn signals in Dallas, Austin, Laredo and San Angelo.

They do use those in North Carolina, but the ones I've seen are:
R
R
Y
G

I probably have a photo or two in the collection somewhere.

[roadfro]

If I recall correctly, the next revision of the MUTCD is proposing to make red arrows a standard with protected left turns.  This would mean a full red green/yellow green/green arrow display would be required.  No more terminating a green arrow with a red ball, and no more all-circular displays with the "left turn signal" sign.



Now, a reply from the budding traffic engineer:

OK - take that one step further. What states are using the part-time protected only turn, with a flashing yellow arrow during off-peak periods allowing a permissive left? In Colorado along CDOT-maintained routes, Pueblo seems to be the primary place where they are being evaluated. FYI, they are not used when there are multiple turn lanes; protected-only turns are indicated for that situation.

Right now, the flashing yellow arrow (FYA) is used on an experimental basis.  Jurisdictions wishing to experiment with it must apply for it through the FHWA.  A list of the jurisdictions that have interim approval from the FHWA to implement the FYA can be found here (scroll down to "IA-10" in the table)  Note that the granting of interim approval does not necessarily mean the agency is actually using it--I don't believe Carson City, NV has currently implemented a FYA.

In the 2009 MUTCD, FYA is currently proposed as the suggested standard for protected/permitted left turn (PPLT) signals, with the current 5-section/doghouse signal heads retained as an option.  Other methods of depicting a permissive left turn (i.e. flashing green arrow, flashing red arrow, flashing red ball, etc.) would no longer be allowed.  FYA, like typical PPLT situations, can only be implemented where there is only one turn lane on the approach.

I don't think the flashing yellow arrow is a good idea, at least in Missouri, where flashing yellow is used for inactive signals - such as fire station signals on state roads, or many signals during the late night/early morning hours.  I also cannot recall ever seeing anyone fail to understand "left turn yield on [green ball]," so I have doubts about the need for it.

While the use of flashing yellow at emergency signals is clearly understood, many jurisdictions have been changing these to full red/yellow/green operations (many emergency signals along major arterials in Las Vegas have had this change).  Additionally, many jurisdictions have been phasing out the yellow & red flash operations during the late night hours, as modern signal technology can better address low volume situations while maintaining full operation (using multiple timing plans and better detection).  Even where those flashing operations still exist, the flashing yellow in these instances conveys the message "proceed with caution".  This is the same message conveyed through FYA, just as an arrow form instead of a ball.

FYA was brought about in part because not all drivers understand the "left turn yield on [green ball]" concept.  Another consideration the elimination of conflicting displays, as in the case of a lead-lead protected turn where drivers see a red ball and a green arrow in the same display simultaneously.  Yet another consideration is that the current 5-section PPLT display does not easily lend itself to lead-lag left turn operations (which is desirable in signal coordination) without some kind of modification, creating the "yellow trap" situation.  The FYA display does have the benefit of easily switching between protected-only and permissive-only modes without having to worry about the green ball of the normal 5-section display.

There has been considerable discussion and research about FYA in the traffic engineering realm over the last ~10 years.  The research has been showing increased comprehension and compliance compared to the 5-section PPLT displays.  In several field studies where it has been implemented, there has also been reductions in left-turn accidents where the left turning driver inappropriately assumed the right-of-way.  More and more agencies nationwide have been interested in FYA, and the positive research results have been what has led FHWA to propose making it standard in the next MUTCD.  With that said, there are some agencies that are still not quite convinced.  I know Las Vegas has been skeptical of the FYA, instead preferring their own modification to the 5-section display when the left turn runs protected-only modes.


If you're interested in more specifics, search for "NCHRP 3-54" (research project) or "NCHRP 493" (report).

[Alex]

Nice bit of information there roadfro.

The flashing green ball concept was used in Delaware at a couple of intersections through the 1990s. The two that I knew of were switched to standard signal cycles by the early 2000s. Around the late 1990s, Delaware also introduced the "T" signals with a red ball and flashing red arrow. The premise was that drivers could turn after making a complete stop if the traffic was clear. If a driver waited long enough, the flashing red arrow would become static and the signals in the opposite direction would cycle in a conventional manner to allow the turn movement. These too were phased out by the mid-2000s.

[Revive 755]

While the use of flashing yellow at emergency signals is clearly understood, many jurisdictions have been changing these to full red/yellow/green operations (many emergency signals along major arterials in Las Vegas have had this change).  Additionally, many jurisdictions have been phasing out the yellow & red flash operations during the late night hours, as modern signal technology can better address low volume situations while maintaining full operation (using multiple timing plans and better detection).  Even where those flashing operations still exist, the flashing yellow in these instances conveys the message "proceed with caution".  This is the same message conveyed through FYA, just as an arrow form instead of a ball.

Better address low volume situations?  I'm not convinced.  And I definitely don't think detection is better today; video detection seems to malfunction too much, and I've seen lots of intersections where a leading arrow won't come up at all lately.  

The message I've grown up with for flashing yellow is "side traffic has a flashing red, expect them to stop but watch them in case they pull out."

FYA was brought about in part because not all drivers understand the "left turn yield on [green ball]" concept.

I think/have seen more drivers have a problem understanding "Exit Only," or wonder if some of them are flipping coins to make driving decisions.

If you're interested in more specifics, search for "NCHRP 3-54" (research project) or "NCHRP 493" (report).

I've looked through the report.  First question:  is main road flashing yellow/side road flashing red used in the studied states (Texas, Michigan, Delaware, Oregon, Washington, California, and Florida)?  Second question:  Why didn't they study a few more alternatives, such as use of a flashing green ball or flashing green arrow as long as they undertook the study?  Also, the study appears to have not looked at the effects of using a "Left Turn Yield On [green ball]" sign, nor Illinois's blank out left turn yield display (example:  http://maps.google.com/maps?hl=en&ie=UTF8&ll=38.543869,-90.195265&spn=0,359.912109&z=14&layer=c&cbll=38.54375,-90.195297&panoid=I2vwlqS0q3q0bm7XWldd4w&cbp=12,208.21289062499991,,0,-17.939453124999996)

After reading this and a few other studies, I think a better solution would be better driver's education, better testing, and maybe requiring an occasional refresher courses for the 65+ age group.

[Bryant5493]

Here some intersections, all of which are located in North Clayton County, Georgia, that use a red arrow for protected turns when the light is, of course, red (lol).


The first photo is of the intersection of SR 85 and Garden Walk/East Garden Walk Boulevards.

The second photo is of the intersection of Riverdale Road (SR 139) and Flat Shoals Road.

The third photo is of the intersection of Riverdale Road (SR 139) and Phoenix Boulevard/Forest Parkway (Old Sullivan Road).


Be well,

Bryant

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[PAHighways]

I think/have seen more drivers have a problem understanding "Exit Only," or wonder if some of them are flipping coins to make driving decisions.

I had one of them e-mail me once asking why I had an exit on my I-70 Exit Guide marked as such when the Interstate continues beyond that interchange.

[yanksfan6129]

I'm gonna half-take-back what I had said about NJ traffic signals earlier. In my town, just yesterday, they installed a new traffic signal that was in the PA style on PennDotFan's old avatar: you know, the top being a light and then two side by side two thingies. And since I've been looking the past few days around NJ for 'em, I've seen that about 30% are that style and the others are all the "inline four" style.

[Alex]

The flashing green ball concept was used in Delaware at a couple of intersections through the 1990s. The two that I knew of were switched to standard signal cycles by the early 2000s. Around the late 1990s, Delaware also introduced the "T" signals with a red ball and flashing red arrow. The premise was that drivers could turn after making a complete stop if the traffic was clear. If a driver waited long enough, the flashing red arrow would become static and the signals in the opposite direction would cycle in a conventional manner to allow the turn movement. These too were phased out by the mid-2000s.

These still existed as late as mid-2005 along US 113.  Have not been along there more recently to see if that's still the case.

On the subject of flashing yellow arrows, I recently came upon a flashing yellow RIGHT arrow, in D.C. on Virginia Ave near Rock Creek Pkwy.  I believe it's due to a large number of pedestrians, but I didn't get a good look at the signage nor did I get a picture (it's on the to-do list).

Delaware had two flashing right yellow arrows at one point. One was along Delaware 2 at Albertson Drive, opposite the one entrance to Price's Corner shopping center. I did snap an image of it with the yellow arrow illuminated here:



A second right-hand yellow arrow in place of a green ball was in use at East Main Street and Kirkwood Highway/Library Avenue in Newark. This is where Delaware 2/2 Business, 72, and 273 come together north of the CSX Railroad overpass. This was removed when the intersection was upgraded from a span wire to a mast-arm based installation.

[roadfro]

Better address low volume situations?  I'm not convinced.  And I definitely don't think detection is better today; video detection seems to malfunction too much, and I've seen lots of intersections where a leading arrow won't come up at all lately.

The red/yellow flash nighttime flash mode is primarily a holdover from the days where traffic signals were only timer based.  The mode prevented unnecessary delays by not making side street vehicles wait a whole cycle for a green, and also by not needlessly stopping main street traffic when no side traffic was present.  Vehicle detection and actuation technology eliminate the need for this mode.  In a late-night low-volume situation, a signal with proper detection operating in fully-actuated R/Y/G mode can operate just as effectively as a signal that is in red/yellow flash mode.

The message I've grown up with for flashing yellow is "side traffic has a flashing red, expect them to stop but watch them in case they pull out."

The problem with that is that a flashing yellow signal does not necessarily have to be at an intersection (i.e. fire station signals, pedestrian crossings).  Here's the official meaning of a flashing yellow from the 2003 MUTCD (Sec. 4D.04):

"Flashing yellow—When a yellow lens is illuminated with rapid intermittent flashes, vehicular traffic is permitted to proceed through the intersection or past such signal indication only with caution."

I've looked through the report.  First question:  is main road flashing yellow/side road flashing red used in the studied states (Texas, Michigan, Delaware, Oregon, Washington, California, and Florida)?  Second question:  Why didn't they study a few more alternatives, such as use of a flashing green ball or flashing green arrow as long as they undertook the study?  Also, the study appears to have not looked at the effects of using a "Left Turn Yield On [green ball]" sign, nor Illinois's blank out left turn yield display (example:  http://maps.google.com/maps?hl=en&ie=UTF8&ll=38.543869,-90.195265&spn=0,359.912109&z=14&layer=c&cbll=38.54375,-90.195297&panoid=I2vwlqS0q3q0bm7XWldd4w&cbp=12,208.21289062499991,,0,-17.939453124999996)

1.) I would wager a guess that most of these jurisdictions are not using red/yellow flash operations (except in maybe in some rural circumstances)...but I cannot speak from experience on that.

2.) A FYA best conveys reflects the situation when compared to the meaning prescribed to flashing signal indications, at least as I read it in the MUTCD.  Using a red indication would imply that a complete stop is required, whereas the yellow indication treats it more like a yield situation (which is exactly the case).  The MUTCD has no provisions or definitions for a flashing green display. 

3.) The meaning of traffic signal indication should be clear and easily understood without supplemental signs (even though that is not always the case), which is probably why the study did not study its effects.  From what I've gleaned in the study, the intent of the PPLT display is not universally understood even with a supplemental sign--from what I've personally seen in Las Vegas, Reno, and other parts of Nevada (where a 5-section doghouse PPLT display is always accompanied by the R10-12 sign), this is indeed the case.