Discussion:
Red lights on with green arrow, in 3-section traffic signals
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Lepidopteran
2004-08-17 19:00:13 UTC
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How long has it been since you've seen the traffic signal sequence of:
a red light (ball/circular) lit at the same time as a green left- or
right-turn arrow, when the traffic signal head has only 3 sections? I
saw a left-turn signal that did this a few weeks ago in a western
suburb of Philadelphia.

The purpose of having a red light lit along with a green turning arrow
is to prevent confusion by telling other traffic going in the same
direction that they still must remain stopped. Indeed, one can see
this all the time with 5-section signals (inline or doghouse) and once
in a while with a 4-section. But except for that one in Pennsylvania,
I don't remember the last time I saw that sequence on a 3-section
signal.

One reason you don't find the r-ga on a 3-section anymore is that many
states have red arrows along with the yellow and green ones, and a red
arrow lit with a green arrow on the same signal head would be
meaningless. Or perhaps it's just a holdover from a time when arrow
indications were new, and motorists were not expected to understand
that only the turning traffic could proceed. Indeed, how many of us
today still jolt forward a bit when the left-only arrow comes on while
we're still red?

Another reason is that today's traffic signal controllers are smarter
than those in years past. Consider this one sequence for a right-turn
arrow on an older system:

GREEN ARROW, along with green on through road
YELLOW BALL, along with yellow on through road
RED BALL with GREEN ARROW, since cross-traffic to the right now has a
protected left. When that protected left ended, the arrow just
disappeared.

In a system installed today, that right-turn signal would "know" in
advance that the cross-traffic is getting a protected left, and
wouldn't even turn yellow in the first place. It would only turn
yellow when that protected left goes to a yellow arrow.

Still another reason is that many of today's protected left turn
signals are not visible from the rest of the traffic flow. This is
typically done by using "louvers" (those thin metal vertical ribs
under the signal visor that make the lens look like a Ruffles potato
chip) or with "programmed visibility" lenses made by 3M.

For a really odd situation, how about a red ball on with a
straight-through arrow? Someone in this newsgroup once posted of a
mutant traffic signal in Massachusetts somewhere that did indeed have
this sequence! He said that the only time the red light was dark was
when the yellow light was lit. (The MUTCD also prohibits yellow or
red straight-through arrows.)
Jeff Kitsko
2004-08-17 20:02:33 UTC
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Post by Lepidopteran
a red light (ball/circular) lit at the same time as a green left- or
right-turn arrow, when the traffic signal head has only 3 sections? I
saw a left-turn signal that did this a few weeks ago in a western
suburb of Philadelphia.
I saw it on Saturday in Greensburg on US 30 at Old Route 30 and PENNDOT
Drive, and US 30 and Eastgate Plaza. PA 56 and Hyde Park Road near New
Kensington has that as well, as you can faintly see at
Loading Image....
Post by Lepidopteran
For a really odd situation, how about a red ball on with a
straight-through arrow?
Saw a four indicator signal in Philadelphia on US 30/Lancaster Avenue with a
red ball and up green arrow back in May.
--
Jeff Kitsko
Pennsylvania Highways: http://www.pahighways.com/
Ohio Highways: http://www.ohhighways.com/
Michael Moroney
2004-08-17 21:51:19 UTC
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Post by Lepidopteran
a red light (ball/circular) lit at the same time as a green left- or
right-turn arrow, when the traffic signal head has only 3 sections? I
saw a left-turn signal that did this a few weeks ago in a western
suburb of Philadelphia.
There is one at the corner of Spit Brook Rd & Daniel Webster Hwy in Nashua
NH, where the rightmost signal (3 head) displays a red ball and right
green arrow at the same time. It also displays a red and yellow ball at
the same time when the green arrow goes out. It's not that old (maybe
8-10 years old).
Post by Lepidopteran
Another reason is that today's traffic signal controllers are smarter
For a really odd situation, how about a red ball on with a
straight-through arrow? Someone in this newsgroup once posted of a
mutant traffic signal in Massachusetts somewhere that did indeed have
this sequence! He said that the only time the red light was dark was
when the yellow light was lit.
Massachusetts has a few odd signals. I know of a combination of those.
A (new BTW) 3 head signal that displays either a red ball, or a red ball
in combination with a green right arrow. The only time the red ball
ever goes out is when the light turns yellow. It is at an intersection
in Fitchburg, where a 2-way road becomes 1-way (the wrong way) and the
cross street is also 1-way. Your only choice at that intersection is to
turn right.

I think there used to be a 5 head signal in Worcester MA that once
displayed a red ball and (left,straight,right) arrows in various
combinations at the same time. Including, I believe, all of them at once.
When I looked for it recently I didn't find it.
Post by Lepidopteran
(The MUTCD also prohibits yellow or
red straight-through arrows.)
Used to be a light on NY 146 & Clifton Country Rd in Clifton Park NY
where the NY 146 WB through lanes had yellow and red straight through
arrows. It otherwise operated as a normal traffic light. (since been
upgraded/fixed)
--
-Mike
Comrade Mr Yamamoto
2004-08-18 00:43:40 UTC
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Loading Image... -The green ball on this light
indicates a protected left, actually. This is at NY 23B and US 9 in Hudson.

Loading Image... and
Loading Image...
the Putnam Valley junction in the town of Cortdland(sp prolly) in
Westchester County.
--
Comrade Mister Yamamoto
http://mryamamoto.50megs.com
"I's so evil, even my shadow don't follow me"
Joe Blasi
2004-08-18 19:51:41 UTC
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Post by Comrade Mr Yamamoto
http://mryamamoto.50megs.com/coco/69.jpg -The green ball on this light
indicates a protected left, actually. This is at NY 23B and US 9 in Hudson.
http://mryamamoto.50megs.com/boxing-week-rush/DCP_2095.jpg and
http://mryamamoto.50megs.com/boxing-week-rush/DCP_2097.jpg
the Putnam Valley junction in the town of Cortdland(sp prolly) in
Westchester County.
--
Comrade Mister Yamamoto
http://mryamamoto.50megs.com
"I's so evil, even my shadow don't follow me"
there one like that hear
http://terraserver.microsoft.com/image.aspx?t=4&s=9&x=4355&y=46465&z=16&w=2
Chris Jordan
2004-08-18 01:13:30 UTC
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Post by Michael Moroney
Used to be a light on NY 146 & Clifton Country Rd in Clifton Park NY
where the NY 146 WB through lanes had yellow and red straight through
arrows. It otherwise operated as a normal traffic light. (since been
upgraded/fixed)
I don't recall ever seeing red and yellow through arrows at that
intersection, only green though arrows.
I know that intersection has gone though a few changes,
a "T" to a 4 way intersection, and one generation of signals, from what I
remember.
But, I can't recall there ever being red and yellow though arrows at that
intersection.

How long ago were was this?
I've been though that intersection occasionally for 20 years,
it's only 15 minutes from my home.
Michael Moroney
2004-08-18 03:14:16 UTC
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Post by Chris Jordan
Post by Michael Moroney
Used to be a light on NY 146 & Clifton Country Rd in Clifton Park NY
where the NY 146 WB through lanes had yellow and red straight through
arrows. It otherwise operated as a normal traffic light. (since been
upgraded/fixed)
I don't recall ever seeing red and yellow through arrows at that
intersection, only green though arrows.
I know that intersection has gone though a few changes,
a "T" to a 4 way intersection, and one generation of signals, from what I
remember.
But, I can't recall there ever being red and yellow though arrows at that
intersection.
How long ago were was this?
This is from back when they built the Clifton Country Mall (& Road),
the first set of lights there, and the lights were probably changed
when it was made into a 4 way there. The mall was built around '76,
I moved away before they built the plaza north of 146.
Post by Chris Jordan
I've been though that intersection occasionally for 20 years,
it's only 15 minutes from my home.
maybe you live in my old house :-) (Clifton Knolls)

Do you know of the colorful NYSDOT experiment that took place just east of
there (146 at the I-87 interchange)?
--
-Mike
Chris Jordan
2004-08-18 04:11:12 UTC
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Post by Michael Moroney
maybe you live in my old house :-) (Clifton Knolls)
Nope, I live in Glenville, off Swaggertown Road.
Post by Michael Moroney
Do you know of the colorful NYSDOT experiment that took place just east of
there (146 at the I-87 interchange)?
I can't really remember anything special about that area.
Can you elaborate?
Michael Moroney
2004-08-18 17:42:09 UTC
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Post by Chris Jordan
Post by Michael Moroney
Do you know of the colorful NYSDOT experiment that took place just east of
there (146 at the I-87 interchange)?
I can't really remember anything special about that area.
Can you elaborate?
Are you familiar with the "white stuff" that NYSDOT once used to form
islands and "don't drive here" areas to separate lanes, around left turn
lanes etc. ? Not concrete but the stuff that was snow-white and looked
great when new, esp. when applied on fresh black asphalt but when old
becomes somewhat like concrete in color. There are not too many places
where it still exists. One I know of is NY 67 at US 4/NY 32 in
Mechanicville. Anyway, they made variations of that in red, yellow and
green and coated the travel lanes on 146 WB starting from about under the
bridge to near the intersection of 146 & Plank Rd/Clifton Park Center Rd
(which no longer ends there). The left turn lane to I-87 SB and the old
ramp from I-87 SB to 146 WB (not the current ramp) were covered in red
(meaning you had to yield/stop), the right lane of 146 was yellow (warning
of merging traffic from the I-87 ramp) and the left lane was green (no
problemo). For years you could see the colors, less and less every year as
it chipped off/potholes were fixed. You can't see any evidence any more.
It was probably done when they built the interchange or maybe not long
after, it was applied directly on top of the original concrete.
--
-Mike
Chris Jordan
2004-08-18 20:39:38 UTC
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"Michael Moroney" <***@world.std.spaamtrap.com> wrote in message
news:cg04dh$s86
Post by Michael Moroney
Are you familiar with the "white stuff" that NYSDOT once used to form
islands and "don't drive here" areas to separate lanes, around left turn
lanes etc. ? Not concrete but the stuff that was snow-white and looked
great when new, esp. when applied on fresh black asphalt but when old
becomes somewhat like concrete in color.
I do not recall that stuff, a sand resin, being used in travel lanes itself.
But I know NYSDOT used it in center turn lanes back in the mid 80s.

There were several places where they were used, but after years of weather
and travel,
the resin goes away and the asphalt underneath gets exposed.

NY 146 between 146A and the Northway still has this stuff in use,
but with each successive work on 146,
the stuff is simply replaced with the usual painted safety zone lines.

It also was very hard for DOT to remove when they needed to add a lane,
like a left turn lane at an intersection.
This is obvious at NY 32 and NY 787 in Cohoes.
Michael Moroney
2004-08-18 21:26:20 UTC
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Post by Chris Jordan
news:cg04dh$s86
Post by Michael Moroney
Are you familiar with the "white stuff" that NYSDOT once used to form
islands and "don't drive here" areas to separate lanes, around left turn
lanes etc. ? Not concrete but the stuff that was snow-white and looked
great when new, esp. when applied on fresh black asphalt but when old
becomes somewhat like concrete in color.
I do not recall that stuff, a sand resin, being used in travel lanes itself.
But I know NYSDOT used it in center turn lanes back in the mid 80s.
I suspect that one conclusion from the colored pavement experiment was the
stuff doesn't hold up to constantly being driven over, but was OK for
narrow pseudo-medians and forming areas around left turn lanes. I am
guessing here the white stuff was an outgrowth of the colored pavement
experiment.
Post by Chris Jordan
It also was very hard for DOT to remove when they needed to add a lane,
like a left turn lane at an intersection.
This is obvious at NY 32 and NY 787 in Cohoes.
I once asked NYSDOT why they don't use this anymore. They answered that
it was expensive, needs separate or specially cleaned equipment to put
down (from stray asphalt) and when removed needs to be disposed of properly
because of the resin. The sand apparently came from a special mine in
New Jersey.
--
-Mike
Shawn K. Quinn
2004-08-18 16:02:51 UTC
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Post by Michael Moroney
There is one at the corner of Spit Brook Rd & Daniel Webster Hwy in Nashua
NH, where the rightmost signal (3 head) displays a red ball and right
green arrow at the same time.  It also displays a red and yellow ball at
the same time when the green arrow goes out.  It's not that old (maybe
8-10 years old).
I remember a left turn signal that did this here in Houston somewhere (I
want to say somewhere on Richmond on a minor street near the Sam Houston
Tollway but I could be wrong). This is probably an electrical problem
causing the red ball to remain on all the time.
--
Shawn K. Quinn
Mitsguy2001
2004-08-24 02:33:11 UTC
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Post by Michael Moroney
Massachusetts has a few odd signals. I know of a combination of those.
A (new BTW) 3 head signal that displays either a red ball, or a red ball
in combination with a green right arrow. The only time the red ball
ever goes out is when the light turns yellow. It is at an intersection
in Fitchburg, where a 2-way road becomes 1-way (the wrong way) and the
cross street is also 1-way. Your only choice at that intersection is to
turn right.
A really dangerous situation is at an intersection such as Cambridgeside Place
/ Charles Street / First Street. You guessed it, in Cambridge, MA.
Cambridgeside Place is two-way, and changes name to Charles Street when it
crosses First Street, and becomes one-way the wrong way (into the
intersection). First Street is two-way. When Cambridgeside gets the green,
rather than a green ball, it gets a green left arrow and a green right arrow,
indicating you can turn left or right, but not straight. Unfortunately,
Charles Street has the green light at the same time. So, you have a left
arrow, which in any other state means you have a protected left, but you also
have opposing traffic, that you must yield the right of way to, but no
indication of the oposing traffic. I'm surprised there aren't constant
accidents at that intersection.
Dave Barber
2004-10-28 14:07:37 UTC
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A really dangerous situation is at an intersection such as Cambridgeside Place /
Charles Street / First Street ... Cambridgeside Place is two-way, and changes
name to Charles Street when it crosses First Street, and becomes one-way the
wrong way (into the intersection). First Street is two-way. When Cambridgeside
gets the green, rather than a green ball, it gets a green left arrow and a green
right arrow, indicating you can turn left or right, but not straight.
Unfortunately, Charles Street has the green light at the same time. So, you
have a left arrow, which in any other state means you have a protected left, but
you also have opposing traffic, that you must yield the right of way to, but no
indication of the oposing traffic ...
This is one example of why I'd love to see a flashing green arrow used for the
left turn when you have to yield. I preach a sermon on this subject at

http://home.earthlink.net/~tamivox/dave/traffic/fga/

- - Dave
John S
2004-10-28 14:21:50 UTC
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Post by Dave Barber
A really dangerous situation is at an intersection such as Cambridgeside Place /
Charles Street / First Street ... Cambridgeside Place is two-way, and changes
name to Charles Street when it crosses First Street, and becomes one-way the
wrong way (into the intersection). First Street is two-way. When Cambridgeside
gets the green, rather than a green ball, it gets a green left arrow and a green
right arrow, indicating you can turn left or right, but not straight.
Unfortunately, Charles Street has the green light at the same time. So, you
have a left arrow, which in any other state means you have a protected left, but
you also have opposing traffic, that you must yield the right of way to, but no
indication of the oposing traffic ...
This is one example of why I'd love to see a flashing green arrow used for the
left turn when you have to yield.
Real bad idea. There is nothing special about Massachusetts that requires special
traffic signals and more confusion. A green arrow means protected turn. If the turn
is not protected there should be a ball. This intersection light should be fixed.
Ron Newman
2004-10-28 15:56:24 UTC
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Post by John S
A green arrow means protected turn. If the turn
is not protected there should be a ball.
If you had a green ball, people would go straight across into the wrong-way
street. The left and right arrows make it clear that you have to turn.
t***@cotse.net
2004-10-28 19:14:26 UTC
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Post by Ron Newman
Post by John S
A green arrow means protected turn. If the turn
is not protected there should be a ball.
If you had a green ball, people would go straight across into the wrong-
way
Post by Ron Newman
street. The left and right arrows make it clear that you have to turn.
There is another solution, Why not just make it a
protected turn, after all? Force the opposing
traffic to stop while the left-or-right only
street has the green arrows. If I were in
charge, I'd also put in lots of "wrong
way", "do not enter" and so on signs,
as well as directional black and white arrows
and the like.

Besides, doesn't MA get lots of international
visitors? The signs should be very clear.




I am not a lawyer. I do not even see email sent to this address, due to
past DOS attacks. If you wish to respond, do so through this newsgroup.
Kevin Flynn
2004-10-29 00:12:52 UTC
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Post by Ron Newman
Post by John S
A green arrow means protected turn. If the turn
is not protected there should be a ball.
If you had a green ball, people would go straight across into the wrong-way
street. The left and right arrows make it clear that you have to turn.
Since green left arrow means a protected turn, then this is the wrong
signal to use in this case, as it is not protected. Green ball is
appropriate, but again, there must be adequate signage to alert
drivers not to continue straight. ("Do Not Enter" etc)

This situation raises a question as to whether the standards could be
revised to address it better. My suggestion is that an overhead signal
assembly with a red "X" above the through lane on the far side of the
intersection would make it clear you cannot go straight. The liability
from having an accident using a green arrow when it is not a protected
left should be taken into consideration.
John S
2004-10-29 02:11:01 UTC
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Post by Ron Newman
Post by John S
A green arrow means protected turn. If the turn
is not protected there should be a ball.
If you had a green ball, people would go straight across into the wrong-way
street.
With all respect Ron, that's rubbish. The green ball gives on permission to
enter the intersection. It doesn't allow somebody to enter a one way street in
the wrong direction. Just as if there was no signal at all, the one way street
needs to be protected by DO NOT ENTER signs, WRONG WAY signs farther down, and
possibly Black on Yellow either way arrow signs. In addition, MUTCD pavement
markings can indicate left and right turns if desired. This is the same
situation as everyplace else with a similar configuration.
Post by Ron Newman
The left and right arrows make it clear that you have to turn.
No, arrows mean PROTECTED turn. A green arrow should never be lit when
opposing traffic is also permitted that interferes with that arrow. The MUTCD
is quite clear about this, and so are driving manuals, including
Massachusetts'.

If a permissive left signal is needed, a separate signal can be used for left
turns, but it needs to be a ball, not an arrow.

But why not simply make the existing left arrow protected and thus compliant
and safe?
J Mello
2004-10-29 13:17:09 UTC
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Post by John S
Post by Ron Newman
Post by John S
A green arrow means protected turn. If the turn
is not protected there should be a ball.
If you had a green ball, people would go straight across into the wrong-way
street.
With all respect Ron, that's rubbish. The green ball gives on permission to
enter the intersection. It doesn't allow somebody to enter a one way street in
the wrong direction. Just as if there was no signal at all, the one way street
needs to be protected by DO NOT ENTER signs, WRONG WAY signs farther down, and
possibly Black on Yellow either way arrow signs. In addition, MUTCD pavement
markings can indicate left and right turns if desired. This is the same
situation as everyplace else with a similar configuration.
Post by Ron Newman
The left and right arrows make it clear that you have to turn.
No, arrows mean PROTECTED turn. A green arrow should never be lit when
opposing traffic is also permitted that interferes with that arrow. The MUTCD
is quite clear about this, and so are driving manuals, including
Massachusetts'.
Green arrows also endanger pedestrians. A ball would allow peds to
have a concurrent walk signal and require turning drivers to yield.
This is how most intersections in both Philly and New York work.

-JMello
Monte Castleman
2004-10-29 20:39:19 UTC
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Post by J Mello
Green arrows also endanger pedestrians. A ball would allow peds to
have a concurrent walk signal and require turning drivers to yield.
This is how most intersections in both Philly and New York work.
Pedestrians aren't supposed to be in the intersection during a green arrow
phase anyway. That's what the "don't walk" light is for.
--
--^\____
| / Monte Castleman, <<Spamfilter in Use>>
| / Bloomington, MN <<to email, remove the "q" from address>>
| |
| *| Visit my Minnesota Highways Page:
|_____\ http://home.earthlink.net/~northstarhighways
Alan Hamilton
2004-10-30 03:07:25 UTC
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On Fri, 29 Oct 2004 20:39:19 GMT, Monte Castleman
Post by Monte Castleman
Post by J Mello
Green arrows also endanger pedestrians. A ball would allow peds to
have a concurrent walk signal and require turning drivers to yield.
This is how most intersections in both Philly and New York work.
Pedestrians aren't supposed to be in the intersection during a green arrow
phase anyway. That's what the "don't walk" light is for.
Right, but if there's only an arrow cycle, you then have to have
pedestrians-only cycle.
--
/
/ * / Alan Hamilton
* * ***@arizonaroads.com

Arizona Roads -- http://www.arizonaroads.com
J Mello
2004-10-30 12:40:00 UTC
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Post by Monte Castleman
Post by J Mello
Green arrows also endanger pedestrians. A ball would allow peds to
have a concurrent walk signal and require turning drivers to yield.
This is how most intersections in both Philly and New York work.
Pedestrians aren't supposed to be in the intersection during a green arrow
phase anyway. That's what the "don't walk" light is for.
That's my point, pal. With a green ball peds can legally and safely
cross concurrent with traffic.

-JMello
Monte Castleman
2004-10-31 03:36:07 UTC
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Post by J Mello
Post by Monte Castleman
Pedestrians aren't supposed to be in the intersection during a green arrow
phase anyway. That's what the "don't walk" light is for.
That's my point, pal. With a green ball peds can legally and safely
cross concurrent with traffic.
Agreed. But you said the arrows "endanger" pedestrians. They do not "endanger"
pedestrians unless those pedestrians are illegally in the intersection, pal.
By that rational balls are dangerous to pedestrians because it doesn't protect
them if they choose to break the law by jaywalking diagonally across the
intersection. "Inconvenience" might be a better word, but inconveniencing
pedestrians makes it safer for drivers.
--
--^\____
| / Monte Castleman, <<Spamfilter in Use>>
| / Bloomington, MN <<to email, remove the "q" from address>>
| |
| *| Visit my Minnesota Highways Page:
|_____\ http://home.earthlink.net/~northstarhighways
J Mello
2004-11-01 13:57:19 UTC
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Post by Monte Castleman
Post by J Mello
Post by Monte Castleman
Pedestrians aren't supposed to be in the intersection during a green arrow
phase anyway. That's what the "don't walk" light is for.
That's my point, pal. With a green ball peds can legally and safely
cross concurrent with traffic.
Agreed. But you said the arrows "endanger" pedestrians. They do not "endanger"
pedestrians unless those pedestrians are illegally in the intersection, pal.
The City of Boston and many other municipalities in MA use green
arrows to indicate what direction traffic may move, not a protected
turn. Therefore, pedestrians nearly always have a don't walk signal.
Most of the time, peds are required to push a button and wait 30-90
seconds for a walk signal if it even works. In a city like Boston,
with high ped traffic, this results in the necessity to jaywalk.
Whether right or wrong, many often ignore the ped signal and follow
the traffic signal (technically jaywalking). My point (maybe not clear
to someone outside Boston) is that it is much safer to use a green
ball and "Yield to Pedestrians on Turn" sign in conjunction with a
concurrent ped phase. This is what is done in most other cities with
high ped volumes (Philly doesn't even use ped signals, relying instead
on small- or normal-sized traffic signals to control ped traffic).

-JMello
t***@cotse.net
2004-10-31 18:09:10 UTC
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Post by Monte Castleman
Post by J Mello
Green arrows also endanger pedestrians. A ball would allow peds to
have a concurrent walk signal and require turning drivers to yield.
This is how most intersections in both Philly and New York work.
Pedestrians aren't supposed to be in the intersection during a green arrow
phase anyway. That's what the "don't walk" light is for.
In My "Humble" Opinion:

There's No time during which "pedestrians
are not supposed to be in the intersection"
because pedestrians can take as much time as
they need once they have entered the
intersection legally (assuming there is a
crosswalk). There is no equivalent to "don't
block the intersection" for pedestians.

Furthermore (florida law) if a pedestrian faces
a green arrow and a ball and the pedestrian
does not face an operating pedestrian control
device then he may enter the intersection legally.



I am not a lawyer. I do not even see email sent to this address, due to
past DOS attacks. If you wish to respond, do so through this newsgroup.
John F. Carr
2004-10-31 19:44:41 UTC
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Post by t***@cotse.net
Post by Monte Castleman
Post by J Mello
Green arrows also endanger pedestrians. A ball would allow peds to
have a concurrent walk signal and require turning drivers to yield.
This is how most intersections in both Philly and New York work.
Pedestrians aren't supposed to be in the intersection during a green
arrow
Post by Monte Castleman
phase anyway. That's what the "don't walk" light is for.
There's No time during which "pedestrians
are not supposed to be in the intersection"
because pedestrians can take as much time as
they need once they have entered the
intersection legally (assuming there is a
crosswalk). There is no equivalent to "don't
block the intersection" for pedestians.
Under the current MUTCD and Uniform Vehicle Code the same is
true if you switch cars and pedestrians. Vehicles may take
as long as they want to clear the intersection and pedestrians
who enter after the light changes must yield to vehicles
already in the intersection.

Pedestrian signals are supposed to be timed so that most
pedestrians have exited the road before cross traffic has
a green light. A pedestrian who is in the crosswalk when
the light changes has probably broken the law.
Post by t***@cotse.net
Furthermore (florida law) if a pedestrian faces
a green arrow and a ball and the pedestrian
does not face an operating pedestrian control
device then he may enter the intersection legally.
But when pedestrian signals are installed, as they are
in most dense urban areas, a walk signal may not be
displayed in combination with a conflicting green arrow.
--
John Carr (***@mit.edu)
Alan Hamilton
2004-10-29 04:12:19 UTC
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Post by Ron Newman
Post by John S
A green arrow means protected turn. If the turn
is not protected there should be a ball.
If you had a green ball, people would go straight across into the wrong-way
street. The left and right arrows make it clear that you have to turn.
There's an intersection similar to that near where I live, though the
conflicting path is a crosswalk. It uses a green ball, along with DO
NOT ENTER/WRONG WAY signs.

The only problem that occurs is that some people see the green ball
and don't turn, assuming the opposite traffic will start too.
--
/
/ * / Alan Hamilton
* * ***@arizonaroads.com

Arizona Roads -- http://www.arizonaroads.com
Kevin Flynn
2004-10-28 19:15:33 UTC
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Post by John S
Post by Dave Barber
A really dangerous situation is at an intersection such as Cambridgeside Place /
Charles Street / First Street ... Cambridgeside Place is two-way, and changes
name to Charles Street when it crosses First Street, and becomes one-way the
wrong way (into the intersection). First Street is two-way. When Cambridgeside
gets the green, rather than a green ball, it gets a green left arrow and a green
right arrow, indicating you can turn left or right, but not straight.
Unfortunately, Charles Street has the green light at the same time. So, you
have a left arrow, which in any other state means you have a protected left, but
you also have opposing traffic, that you must yield the right of way to, but no
indication of the oposing traffic ...
This is one example of why I'd love to see a flashing green arrow used for the
left turn when you have to yield.
Real bad idea. There is nothing special about Massachusetts that requires special
traffic signals and more confusion. A green arrow means protected turn. If the turn
is not protected there should be a ball. This intersection light should be fixed.
Agree. The signal should be fixed, We already have a signal for
permitted left, and that's a green ball (in the absence of any other
signed prohibition). My question for Dave is: Does the intersection in
question have adequate signage prohibiting through traffic onto the
opposing one-way street?
Dave Barber
2004-10-29 14:03:12 UTC
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Post by Kevin Flynn
Post by John S
Post by Dave Barber
A really dangerous situation is at an intersection such as Cambridgeside Place /
Charles Street / First Street ... Cambridgeside Place is two-way, and changes
name to Charles Street when it crosses First Street, and becomes one-way the
wrong way (into the intersection).
This is one example of why I'd love to see a flashing green arrow used for the
left turn when you have to yield.
Real bad idea. There is nothing special about Massachusetts that requires special
traffic signals and more confusion. A green arrow means protected turn. If the turn
is not protected there should be a ball. This intersection light should be fixed.
Agree. The signal should be fixed, We already have a signal for
permitted left, and that's a green ball (in the absence of any other
signed prohibition). My question for Dave is: Does the intersection in
question have adequate signage prohibiting through traffic onto the
opposing one-way street?
I haven't seen this intersection, relying only on the original poster's description. I do
agree, however, that when traffic is never permitted to go straight, you do need plenty of
signs.

Consider this different situation, at an ordinary crossroads, all two-way streets. When
southbound traffic has a green dot and a (steady) left turn arrow, northbound straight
traffic must have a red dot. Northbound left-turn traffic could make a left turn after
yielding, if you had a way to indicate that possibility to those drivers.

This is another example of why we need a special signal to indicate the permissive turn.
There is experimentation in a few parts of the United States.

- - Dave
Ron Newman
2004-10-29 15:09:40 UTC
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Post by Dave Barber
This is another example of why we need a special signal to indicate the permissive turn.
Maybe we should introduce a new color? Blue isn't used for anything now.
Dave Barber
2004-10-29 23:39:02 UTC
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Post by Ron Newman
Post by Dave Barber
This is another example of why we need a special signal to indicate the
permissive turn.
Maybe we should introduce a new color? Blue isn't used for anything now.
Blue can be an effective signal color. Railroads use it to warn of rolling
stock that must not be moved because personnel are working on, around, or
underneath it. Evidently they found a shade of blue that differs sufficiently
from green to prevent confustion.

- - Dave
John Mara
2004-10-29 23:41:57 UTC
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Post by Dave Barber
Post by Ron Newman
Post by Dave Barber
This is another example of why we need a special signal to indicate the
permissive turn.
Maybe we should introduce a new color? Blue isn't used for anything now.
Blue can be an effective signal color. Railroads use it to warn of rolling
stock that must not be moved because personnel are working on, around, or
underneath it. Evidently they found a shade of blue that differs sufficiently
from green to prevent confustion.
Isn't Blue - Green color blindness fairly common?

John Mara
Steve
2004-10-29 23:48:52 UTC
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Post by Dave Barber
Post by Dave Barber
Post by Ron Newman
Post by Dave Barber
This is another example of why we need a special signal to indicate
the
Post by Dave Barber
Post by Ron Newman
Post by Dave Barber
permissive turn.
Maybe we should introduce a new color? Blue isn't used for anything
now.
Post by Dave Barber
Blue can be an effective signal color. Railroads use it to warn of rolling
stock that must not be moved because personnel are working on, around, or
underneath it. Evidently they found a shade of blue that differs
sufficiently
Post by Dave Barber
from green to prevent confustion.
Isn't Blue - Green color blindness fairly common?
This is why Europe and Quebec (if not other places) use shape signals.
In Quebec, red squares and yellow triangles (as well as a double-red on
many signals, one on each end of the signal) help differentiate from the
green circles for the color blind. I'd like to see that innovation
passed on, especially now with LED technology that can be made into so
many different shapes so easily.
--
Steve
GO JETS! basketball SUCKS! hockey SUCKS WORSE!
Civil Engineering (Course 1) at MIT
Michael Moroney
2004-10-30 03:27:19 UTC
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Post by Steve
In Quebec, red squares and yellow triangles (as well as a double-red on
many signals, one on each end of the signal) help differentiate from the
green circles for the color blind.
They should have used octagons for the red.
--
-Mike
william lynch
2004-10-30 13:39:41 UTC
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Post by Michael Moroney
Post by Steve
In Quebec, red squares and yellow triangles (as well as a double-red on
many signals, one on each end of the signal) help differentiate from the
green circles for the color blind.
They should have used octagons for the red.
On a rainy (or snowy) night at 35 mph an octagon would look too much
like a circle. An "X" shape would probably be better.
Dave Barber
2004-10-30 13:50:35 UTC
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Post by Michael Moroney
Post by Steve
In Quebec, red squares and yellow triangles (as well as a double-red on
many signals, one on each end of the signal) help differentiate from the
green circles for the color blind.
They should have used octagons for the red.
http://www.unilights.com/ sells those.

- - Dave
Ron Newman
2004-10-31 11:55:04 UTC
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Post by Dave Barber
http://www.unilights.com/ sells those.
I'm intrigued by this:

http://www.unilights.com/specifications/products_IC12.htm

a single-lens signal that alternately displays a red octagon, a yellow
inverted triangle, or a green ball. Is this device used as a regular
traffic light on public roads anywhere in the US?
Brian Purcell
2004-10-30 15:13:38 UTC
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Post by Steve
This is why Europe and Quebec (if not other places) use shape signals.
In Quebec, red squares and yellow triangles (as well as a double-red on
many signals, one on each end of the signal) help differentiate from the
green circles for the color blind. I'd like to see that innovation
passed on, especially now with LED technology that can be made into so
many different shapes so easily.
I've travelled extensively in Europe and never seen that. Only in
Quebec. I personally don't like it.

--Brian Purcell
San Antonio, Texas, USA
mailto:***@texhwyman.com
http://www.texhwyman.com
Steve
2004-10-30 15:25:54 UTC
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Post by Brian Purcell
Post by Steve
This is why Europe and Quebec (if not other places) use shape signals.
In Quebec, red squares and yellow triangles (as well as a double-red on
many signals, one on each end of the signal) help differentiate from the
green circles for the color blind. I'd like to see that innovation
passed on, especially now with LED technology that can be made into so
many different shapes so easily.
I've travelled extensively in Europe and never seen that. Only in
Quebec. I personally don't like it.
I think Switzerland has them too. And I'm all for the different shapes,
though I think the double-red could really confuse the color blind, even
with the square vs. circle.
--
Steve
GO JETS! basketball SUCKS! hockey SUCKS WORSE!
Civil Engineering (Course 1) at MIT
Brian Purcell
2004-10-31 17:11:05 UTC
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Post by Steve
I think Switzerland has them too.
The only shape used in Swiss traffic signals is a flashing yellow
triangle, which is used to indicate that left turns must yield (i.e. a
permissive left, which coincidentally I should also post to the
permissive left signal thread.)

--Brian Purcell
San Antonio, Texas, USA
mailto:***@texhwyman.com
http://www.texhwyman.com
Joe Fineman
2004-10-30 02:44:21 UTC
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Post by John Mara
Isn't Blue - Green color blindness fairly common?
The most common kind, among men anyway, is red-green. My
understanding is that such people learn to go by the position of the
light. Not being color-blind myself, I can't actually remember
whether red or green is on top; but some people bloody well have to.
--
--- Joe Fineman ***@verizon.net

||: Angels are no saints. :||
Brian Purcell
2004-10-30 15:15:19 UTC
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My understanding is that such people learn to go by the position of the
light. Not being color-blind myself, I can't actually remember
whether red or green is on top; but some people bloody well have to.
I never could understand how people don't remember that red is always
on top! :) (It's on the left in horizontal arrangements, BTW.)

--Brian Purcell
San Antonio, Texas, USA
mailto:***@texhwyman.com
http://www.texhwyman.com
Michael Moroney
2004-10-30 03:25:48 UTC
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Post by Dave Barber
Post by Dave Barber
Blue can be an effective signal color. Railroads use it to warn of rolling
stock that must not be moved because personnel are working on, around, or
underneath it. Evidently they found a shade of blue that differs
sufficiently
Post by Dave Barber
from green to prevent confustion.
Dunno which shades railroads use, but there may be a bit more difference
needed, since as I understand it, the green traffic light color is tinged
toward blue (and the red toward orange) to help people with red-green
color blindness. (aside: as a kid I remember a "lime green" traffic light
lens (a yellowish green signal) that we encountered only when visiting
certain relatives, obviously not so tinted)
Post by Dave Barber
Isn't Blue - Green color blindness fairly common?
No. It's red-green color blindness that's rather common (see above).
Other forms are quite rare.
--
-Mike
Dave Barber
2004-10-30 13:10:01 UTC
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Railroads use blue to warn of rolling
stock that must not be moved because personnel are working on, around, or
underneath it. Evidently they found a shade of blue that differs
sufficiently from green to prevent confustion.
... as I understand it, the green traffic light color is tinged
toward blue (and the red toward orange) to help people with red-green
color blindness. (aside: as a kid I remember a "lime green" traffic light
lens (a yellowish green signal)
I remember when the"blue shift" of green lights happened, too. It was maybe in
the middle 1960's.

- - Dave
John Mara
2004-10-30 14:31:21 UTC
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Post by Dave Barber
I remember when the"blue shift" of green lights happened, too. It was maybe in
the middle 1960's.
There is a signal near my house in Albany, NY which must have an old lens on
one head and a new lens on the other. One lens is noticeably bluer than the
other.

John Mara
David Chesler
2004-10-31 14:20:50 UTC
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Post by Michael Moroney
Dunno which shades railroads use, but there may be a bit more difference
needed, since as I understand it, the green traffic light color is tinged
toward blue (and the red toward orange) to help people with red-green
color blindness. (aside: as a kid I remember a "lime green" traffic light
lens (a yellowish green signal) that we encountered only when visiting
certain relatives, obviously not so tinted)
We quickly become used to it, but the shift from incandescent to LED
caused a color shift. I remember noting how much bluer the greens looked.
(Similarly, halogen lights used to seem very blue, but now they look
regular, and the HID lights look blue.)
--
- David Chesler <***@post.harvard.edu>
Iacta alea est
Elmer
2004-11-01 04:50:36 UTC
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Tonight in Boston, heading South on Surface Road towards the I-90/I-93
on-ramps, at the Kneeland Street intersection the traffic signals were
flasing both the green and yellow signals at the same time. The
opposing traffic on Kneeland Street had flashing red signals.

Even with all the screwy signals in Massachusetts, I've never seen
both green and yellow at the same time, either steady or flashing. It
seems like a double-violation of MUTCD rules: green should never be
flashing and green and yellow should never be on at the same time.

What are the people who program these signals thinking? If Kneeland
Street traffic gets a flashing red, then Surface Road should be
flashing yellow. It need not be more complicated than that. Nobody
knows what flashing green and yellow is supposed to mean, and since
there are no signs to give drivers any clue, it will only cause
confusion.

I wonder how many consultants were paid to come up with this brilliant
idea, and then how much more was spent to custom-engineer the traffic
signal controller to do this non-standard, function.

Elmer
Steve
2004-11-01 05:16:32 UTC
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Post by Elmer
Tonight in Boston, heading South on Surface Road towards the I-90/I-93
on-ramps, at the Kneeland Street intersection the traffic signals were
flasing both the green and yellow signals at the same time. The
opposing traffic on Kneeland Street had flashing red signals.
Even with all the screwy signals in Massachusetts, I've never seen
both green and yellow at the same time, either steady or flashing.
Charles Street, Boston. Green/yellow solid for pedestrian phase.
--
Steve
GO JETS! basketball SUCKS! hockey SUCKS WORSE!
Civil Engineering (Course 1) at MIT
Ron Newman
2004-11-01 12:12:48 UTC
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Post by Steve
Post by Elmer
Even with all the screwy signals in Massachusetts, I've never seen
both green and yellow at the same time, either steady or flashing.
Charles Street, Boston. Green/yellow solid for pedestrian phase.
Really? Usually red and yellow together are used for this purpose.
Ron Newman
2004-11-01 12:12:01 UTC
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Post by Elmer
Tonight in Boston, heading South on Surface Road towards the I-90/I-93
on-ramps, at the Kneeland Street intersection the traffic signals were
flasing both the green and yellow signals at the same time. The
opposing traffic on Kneeland Street had flashing red signals.
Yeah I saw that too! I was on a Concord Trailways bus from Manchester
NH that arrived at that intersection around 6:30 last night. The white
WALK lights were also blinking.
Kevin Flynn
2004-10-29 23:57:59 UTC
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Post by Dave Barber
Post by Kevin Flynn
Post by John S
Post by Dave Barber
A really dangerous situation is at an intersection such as Cambridgeside Place /
Charles Street / First Street ... Cambridgeside Place is two-way, and changes
name to Charles Street when it crosses First Street, and becomes one-way the
wrong way (into the intersection).
This is one example of why I'd love to see a flashing green arrow used for the
left turn when you have to yield.
Real bad idea. There is nothing special about Massachusetts that requires special
traffic signals and more confusion. A green arrow means protected turn. If the turn
is not protected there should be a ball. This intersection light should be fixed.
Agree. The signal should be fixed, We already have a signal for
permitted left, and that's a green ball (in the absence of any other
signed prohibition). My question for Dave is: Does the intersection in
question have adequate signage prohibiting through traffic onto the
opposing one-way street?
I haven't seen this intersection, relying only on the original poster's description. I do
agree, however, that when traffic is never permitted to go straight, you do need plenty of
signs.
Consider this different situation, at an ordinary crossroads, all two-way streets. When
southbound traffic has a green dot and a (steady) left turn arrow, northbound straight
traffic must have a red dot. Northbound left-turn traffic could make a left turn after
yielding, if you had a way to indicate that possibility to those drivers.
This is another example of why we need a special signal to indicate the permissive turn.
There is experimentation in a few parts of the United States.
- - Dave
What you suggest is essentially no different than simply allowing
anybody to make any movement when it is safe to do so, something I
would have difficulty supporting because of the huge variance in
individual driving proclivities.

E.g., why just allow drivers to permissively make a left when they
have a red ball to allow opposing protected lefts, as in your new
example above? Why not allow the northbound drivers to proceed
straight through notwithstanding the opposing protected left, if in
fact there are no southbound drivers present to make that left at the
moment?
Dave Barber
2004-10-30 13:45:30 UTC
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Post by Kevin Flynn
Post by Dave Barber
Consider this different situation, at an ordinary crossroads, all two-way streets. When
southbound traffic has a green dot and a (steady) left turn arrow, northbound straight
traffic must have a red dot. Northbound left-turn traffic could make a left turn after
yielding, if you had a way to indicate that possibility to those drivers.
This is another example of why we need a special signal to indicate the permissive turn.
There is experimentation in a few parts of the United States.
What you suggest is essentially no different than simply allowing
anybody to make any movement when it is safe to do so, something I
would have difficulty supporting because of the huge variance in
individual driving proclivities.
A signal can and should give a steady red light to anybody who must stop and, for safety reasons,
stay stopped while some other traffic is permitted to move. (To keep people from turning right on
a red dot, you either post a sign, or show a red right-turn arrow.)

This flashing green left turn arrow I propose indicates to drivers that they must yield to
oncoming straight and right-turn traffic, and pedestrians. But when cross traffic is running, that
arrow needs to be steady red -- you figure that if the intersection needs a traffic light with
protected phases, there must be either heavy traffic, lousy visibility, or complicated traffic
patterns.
Post by Kevin Flynn
... Why not allow the northbound drivers to proceed straight through notwithstanding the
opposing protected left, if in fact there are no southbound drivers present to make that left at
the moment?
That's a legitimate question. If you can clearly and simply communicate to those northbound
drivers that the vehicles to which they must yield are the oncoming vehicles turning left, you're
in business.

- - Dave

http://home.earthlink.net/~tamivox/dave/traffic/fga/
Kevin Flynn
2004-10-31 23:11:27 UTC
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Post by Dave Barber
Post by Kevin Flynn
Post by Dave Barber
Consider this different situation, at an ordinary crossroads, all two-way streets. When
southbound traffic has a green dot and a (steady) left turn arrow, northbound straight
traffic must have a red dot. Northbound left-turn traffic could make a left turn after
yielding, if you had a way to indicate that possibility to those drivers.
This is another example of why we need a special signal to indicate the permissive turn.
There is experimentation in a few parts of the United States.
What you suggest is essentially no different than simply allowing
anybody to make any movement when it is safe to do so, something I
would have difficulty supporting because of the huge variance in
individual driving proclivities.
A signal can and should give a steady red light to anybody who must stop and, for safety reasons,
stay stopped while some other traffic is permitted to move. (To keep people from turning right on
a red dot, you either post a sign, or show a red right-turn arrow.)
This flashing green left turn arrow I propose indicates to drivers that they must yield to
oncoming straight and right-turn traffic, and pedestrians.
But there already is a signal for this -- the green ball. It allows
left-turned to do exactly what you propose, and with one less signal
thrown into the mix. Why add another? Makes no sense IMO.

But when cross traffic is running, that
Post by Dave Barber
arrow needs to be steady red -- you figure that if the intersection needs a traffic light with
protected phases, there must be either heavy traffic, lousy visibility, or complicated traffic
patterns.
Again unnecessary. There already is a signal for when cross-traffis is
running. That's the red light. Your proposals all have the impact of
cluttering up the signal arrays with redundant lights, the more to
confuse drivers, IMO.
Post by Dave Barber
Post by Kevin Flynn
... Why not allow the northbound drivers to proceed straight through notwithstanding the
opposing protected left, if in fact there are no southbound drivers present to make that left at
the moment?
That's a legitimate question. If you can clearly and simply communicate to those northbound
drivers that the vehicles to which they must yield are the oncoming vehicles turning left, you're
in business.
No, that's just called red-light-running. Let's keep people stopped
when there's crossing traffic at a signal. It makes it clearer for
those of us who are approaching the green.
Dave Barber
2004-11-01 01:14:28 UTC
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Post by Kevin Flynn
Post by Dave Barber
This flashing green left turn arrow I propose indicates to drivers that they must yield to
oncoming straight and right-turn traffic, and pedestrians.
But there already is a signal for this -- the green ball. It allows
left-turned to do exactly what you propose, and with one less signal
thrown into the mix. Why add another? Makes no sense IMO.
The following question may get to the heart of our disagreement. What would you do about the "yellow
trap" problem?

- - Dave

http://home.earthlink.net/~tamivox/dave/traffic/fga/
Alan Hamilton
2004-11-01 07:53:23 UTC
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Post by Dave Barber
Post by Kevin Flynn
Post by Dave Barber
This flashing green left turn arrow I propose indicates to drivers that they must yield to
oncoming straight and right-turn traffic, and pedestrians.
But there already is a signal for this -- the green ball. It allows
left-turned to do exactly what you propose, and with one less signal
thrown into the mix. Why add another? Makes no sense IMO.
The following question may get to the heart of our disagreement. What would you do about the "yellow
trap" problem?
Either use leading arrows (before the thru traffic cycle) or make
lagging arrows the same length in both directions.
--
/
/ * / Alan Hamilton
* * ***@arizonaroads.com

Arizona Roads -- http://www.arizonaroads.com
Dave Barber
2004-11-01 13:58:48 UTC
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Post by Alan Hamilton
What would you do about the "yellow trap" problem?
Either use leading arrows (before the thru traffic cycle) or make
lagging arrows the same length in both directions.
Those are widely-implemented solutions, and they frequently are satisfactory. However, in the heaviest
traffic, lagging arrows of different durations can be beneficial for reducing congestion. Such arrows
produce the yellow trap unless something is done to prevent it.

Another case: when a side street of very light usage crosses a main artery, a "smart" controller can skip
phases for the side street when nobody is waiting there, and save time for the folks on the major street.
But this phase skipping can lead to the yellow trap, also.

Congestion itself is a cause of crashes, particularly rear-end collisions. Also, drivers frustrated by
clogged traffic sometimes try risky moves to bypass the problem, perhaps causing more crashes. That's why
engineers seek ways to squeeze a few more cars through the intersection.

- - Dave

http://home.earthlink.net/~tamivox/dave/traffic/fga/
Ron Newman
2004-11-01 12:13:27 UTC
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Post by Dave Barber
The following question may get to the heart of our disagreement. What would
you do about the "yellow trap" problem?
What does this mean?
Dave Barber
2004-11-01 14:01:08 UTC
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Post by Ron Newman
What would you do about the "yellow trap" problem?
What does this mean?
http://projects.kittelson.com/pplt/LearnAbout/Learn3.htm

- - Dave

Shawn M Provencal
2004-10-30 05:05:07 UTC
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Post by Dave Barber
This is another example of why we need a special signal to indicate the permissive turn.
There is experimentation in a few parts of the United States.
- - Dave
Isn't that what a green ball is for though? Why introduce yet another signal?
A yellow blinking arrow seems unnecessary when you have the usual green ball
with the sign 'Left turn yield on ()' where () is a green ball. Boston is
plagued with too many arrows as it is IMO.. arrows with red balls, arrows
pointing every possible direction one might go at an intersection lit up
all at once, arrows poiting left with a sign no right turn..

I think these most of these arrows are because noone expects people to read
a sign such as "no right turn", "do not enter", or whatnot.

What's next.. a blue blinking arrow?

Before this, I think Boston needs to address many MDC/DCR roads with red
balls with arrows, intersections with 3 or 4 lanes on one side and 2 lanes
on the other side of the intersection, merges of 2 lanes into 2 lanes of
traffic (ie, soldiers field road near the alewife brook parkway), 2
sources of traffic getting a green ball and having to merge (fresh pond
parkway near route 2)

-Shawn
Dave Barber
2004-10-30 14:05:52 UTC
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Post by Dave Barber
This is another example of why we need a special signal to indicate the permissive turn.
There is experimentation in a few parts of the United States.
Isn't that what a green ball is for though? Why introduce yet another signal? A yellow
blinking arrow seems unnecessary when you have the usual green ball with the sign 'Left turn
yield on ()' where () is a green ball.
It is tricky to give left-turn traffic a green dot if the straight-thru traffic in the
adjoining lane has a red dot -- drivers see the two different colors of dots and might think
the signal is broken. The "Dallas display" addresses this problem, although not with complete
success.
... arrows with red balls, arrows pointing every possible direction one might go at an
intersection lit up all at once, arrows poiting left with a sign no right turn. I think
these most of these arrows are because noone expects people to read a sign such as "no right
turn", "do not enter", or whatnot.
At nighttime, a traffic light is far more conspicuous than a sign.
What's next.. a blue blinking arrow?
Actually, blue lights have now developed their own subthread. :-)

- - Dave
Eric Opperman
2004-11-01 01:47:43 UTC
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Post by Dave Barber
Post by Dave Barber
This is another example of why we need a special signal to indicate the permissive turn.
There is experimentation in a few parts of the United States.
Isn't that what a green ball is for though? Why introduce yet another signal? A yellow
blinking arrow seems unnecessary when you have the usual green ball with the sign 'Left turn
yield on ()' where () is a green ball.
It is tricky to give left-turn traffic a green dot if the straight-thru traffic in the
adjoining lane has a red dot -- drivers see the two different colors of dots and might think
the signal is broken. The "Dallas display" addresses this problem, although not with complete
success.
... arrows with red balls, arrows pointing every possible direction one might go at an
intersection lit up all at once, arrows poiting left with a sign no right turn. I think
these most of these arrows are because noone expects people to read a sign such as "no right
turn", "do not enter", or whatnot.
At nighttime, a traffic light is far more conspicuous than a sign.
You could do what Belleville, Illinois does -- have a sign next to the
traffic light that illuminates "LEFT TURN YIELD" in white LED's when
opposing traffic has the green ball.
Bxdanny
2004-10-30 16:22:25 UTC
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I don't think most drivers would assume that a green arrow by itself
means a "protected" turn, even if a literal reading of the MUTCD says it
does.

Probably the rules should specify that a green arrow IN COMBINATION WITH
a ball means a protected turn, but by itself it simply means a
permissive turn (with other movements that don't have arrows generally
prohibited).
Post by Dave Barber
Post by Kevin Flynn
Post by John S
Post by Dave Barber
A really dangerous situation is at an intersection such as Cambridgeside Place /
Charles Street / First Street ... Cambridgeside Place is two-way, and changes
name to Charles Street when it crosses First Street, and becomes one-way the
wrong way (into the intersection).
This is one example of why I'd love to see a flashing green arrow used for the
left turn when you have to yield.
Real bad idea. There is nothing special about Massachusetts that requires special
traffic signals and more confusion. A green arrow means protected turn. If the turn
is not protected there should be a ball. This intersection light should be fixed.
Agree. The signal should be fixed, We already have a signal for
permitted left, and that's a green ball (in the absence of any other
signed prohibition). My question for Dave is: Does the intersection in
question have adequate signage prohibiting through traffic onto the
opposing one-way street?
I haven't seen this intersection, relying only on the original poster's description. I do
agree, however, that when traffic is never permitted to go straight, you do need plenty of
signs.
Consider this different situation, at an ordinary crossroads, all two-way streets. When
southbound traffic has a green dot and a (steady) left turn arrow, northbound straight
traffic must have a red dot. Northbound left-turn traffic could make a left turn after
yielding, if you had a way to indicate that possibility to those drivers.
This is another example of why we need a special signal to indicate the permissive turn.
There is experimentation in a few parts of the United States.
- - Dave
John S
2004-10-30 16:41:40 UTC
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Post by Bxdanny
I don't think most drivers would assume that a green arrow by itself
means a "protected" turn, even if a literal reading of the MUTCD says it
does.
That's what it has meant for as long as I can remember, all over the USA. It's in driver's
manuals, driver's education, and driver's exams. It's also pretty clear to drivers due to the
standard practice.
Post by Bxdanny
Probably the rules should specify that a green arrow IN COMBINATION WITH
a ball means a protected turn, but by itself it simply means a
permissive turn (with other movements that don't have arrows generally
prohibited).
That doesn't make any sense, especially since left arrows are often lit while opposite traffic
also has a left arrow. If you illuminate a green ball then, your signal is causing a a
conflict. The general prohibition on other movements is accomplished by the lack of a green
ball (and the necessary red indication).
Kevin Flynn
2004-10-31 23:04:34 UTC
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Post by Bxdanny
Post by Dave Barber
Post by Kevin Flynn
Post by John S
Post by Dave Barber
A really dangerous situation is at an intersection such as Cambridgeside Place /
Charles Street / First Street ... Cambridgeside Place is two-way, and changes
name to Charles Street when it crosses First Street, and becomes one-way the
wrong way (into the intersection).
This is one example of why I'd love to see a flashing green arrow used for the
left turn when you have to yield.
Real bad idea. There is nothing special about Massachusetts that requires special
traffic signals and more confusion. A green arrow means protected turn. If the turn
is not protected there should be a ball. This intersection light should be fixed.
Agree. The signal should be fixed, We already have a signal for
permitted left, and that's a green ball (in the absence of any other
signed prohibition). My question for Dave is: Does the intersection in
question have adequate signage prohibiting through traffic onto the
opposing one-way street?
I haven't seen this intersection, relying only on the original poster's description. I do
agree, however, that when traffic is never permitted to go straight, you do need plenty of
signs.
Consider this different situation, at an ordinary crossroads, all two-way streets. When
southbound traffic has a green dot and a (steady) left turn arrow, northbound straight
traffic must have a red dot. Northbound left-turn traffic could make a left turn after
yielding, if you had a way to indicate that possibility to those drivers.
This is another example of why we need a special signal to indicate the permissive turn.
There is experimentation in a few parts of the United States.
I don't think most drivers would assume that a green arrow by itself
means a "protected" turn, even if a literal reading of the MUTCD says it
does.
Probably the rules should specify that a green arrow IN COMBINATION WITH
a ball means a protected turn, but by itself it simply means a
permissive turn (with other movements that don't have arrows generally
prohibited).
This is the exact opposite of current law and practice. I disagree. I
think most drivers not only assume but *know* because it is the law
that a green arrow means a protected left. The signal is telling you
there is not a conflict with oncoming traffic. Your suggestion of an
arrow with a green ball wouldn't mean the same thing. That combination
would merely indicate that a protected left phase for the opposing
direction has come to an end.

To have a green ball in combination with a green left arrow would
essentially eliminate the opportunity to have dual protected left
turns from both opposing directions, still the most common left-turn
phasing in signals around my area despite the growth of
leading-lagging left phases.

For a green ball-green arrow combo to be the norm for all protected
lefts wouldn't be a viable option, then.
David S Chesler
2004-10-28 20:45:20 UTC
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Post by John S
Post by Dave Barber
This is one example of why I'd love to see a flashing green arrow used
for the left turn when you have to yield.
Real bad idea. There is nothing special about Massachusetts that requires
special traffic signals and more confusion. A green arrow means protected
turn. If the turn is not protected there should be a ball. This
intersection light should be fixed.
Agreed. Is there a "standard" way to indicate, near the signal head,
"Although you have a green ball, which normally means you can go
straight, left, or right, at least when the cross-street isn't
one way, this is a case where you can't go straight across the
intersection, so you shouldn't do what you normally do most of
the times when you're looking at a green ball"?

I understand from past discussions that a red arrow (as used e.g. on
Revere Beach Parkway) is deprecated, and between MUTCD versions
varies as to whether it is saying "Movement in this direction
is prohibited" or "As to movement in this direction, if I were
green I'd be telling you you have right of way to go in that
direction, but since I'm not, you don't, and the normal yielding
rules apply."
--
- David Chesler <***@post.harvard.edu>
Iacta alea est
John S
2004-10-29 02:16:17 UTC
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Post by David S Chesler
Post by John S
Post by Dave Barber
This is one example of why I'd love to see a flashing green arrow used
for the left turn when you have to yield.
Real bad idea. There is nothing special about Massachusetts that requires
special traffic signals and more confusion. A green arrow means protected
turn. If the turn is not protected there should be a ball. This
intersection light should be fixed.
Agreed. Is there a "standard" way to indicate, near the signal head,
"Although you have a green ball, which normally means you can go
straight, left, or right, at least when the cross-street isn't
one way, this is a case where you can't go straight across the
intersection, so you shouldn't do what you normally do most of
the times when you're looking at a green ball"?
I understand from past discussions that a red arrow (as used e.g. on
Revere Beach Parkway) is deprecated, and between MUTCD versions
varies as to whether it is saying "Movement in this direction
is prohibited" or "As to movement in this direction, if I were
green I'd be telling you you have right of way to go in that
direction, but since I'm not, you don't, and the normal yielding
rules apply.
A green ball never means that you can necessarily go across the intersection.
In this case, standard signage needs to indicate that one is not permitted to
enter the wrong way street. The same signage would be required if there was no
traffic light.

Some states (e.g. Pennsylvania) do not use red arrows at all, and use only green
and yellow arrows. If a no left turn signal is needed, it is a separate
labeled left turn signal with a red ball. This is MUTCD compliant, as are red
arrows. (The Pennsylvania driver's manual describes red arrows so they are not
a surprise to new drivers out-of-state. It doesn't explain blinking green
lights, yellow+red lights, and secret unprotected green arrows).
Kevin Flynn
2004-10-29 15:27:01 UTC
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Post by David S Chesler
Post by John S
Post by Dave Barber
This is one example of why I'd love to see a flashing green arrow used
for the left turn when you have to yield.
Real bad idea. There is nothing special about Massachusetts that requires
special traffic signals and more confusion. A green arrow means protected
turn. If the turn is not protected there should be a ball. This
intersection light should be fixed.
Agreed. Is there a "standard" way to indicate, near the signal head,
"Although you have a green ball, which normally means you can go
straight, left, or right, at least when the cross-street isn't
one way, this is a case where you can't go straight across the
intersection, so you shouldn't do what you normally do most of
the times when you're looking at a green ball"?
Yes there is. "Do Not Enter."
J Mello
2004-10-29 19:18:53 UTC
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Post by David S Chesler
Post by John S
Post by Dave Barber
This is one example of why I'd love to see a flashing green arrow used
for the left turn when you have to yield.
Real bad idea. There is nothing special about Massachusetts that requires
special traffic signals and more confusion. A green arrow means protected
turn. If the turn is not protected there should be a ball. This
intersection light should be fixed.
Agreed. Is there a "standard" way to indicate, near the signal head,
"Although you have a green ball, which normally means you can go
straight, left, or right, at least when the cross-street isn't
one way, this is a case where you can't go straight across the
intersection, so you shouldn't do what you normally do most of
the times when you're looking at a green ball"?
Yes there is. This sign

Loading Image...

should be posted on one or both traffic signal posts, or hung above the roadway.

-JMello
Dave Barber
2004-10-29 14:09:03 UTC
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Post by Dave Barber
A really dangerous situation is at an intersection such as Cambridgeside Place /
Charles Street / First Street ... Cambridgeside Place is two-way, and changes
name to Charles Street when it crosses First Street, and becomes one-way the
wrong way (into the intersection). ..
This is one example of why I'd love to see a flashing green arrow used for the
left turn when you have to yield.
... A green arrow means protected turn. ...
I agree that a *steady* green arrow means a protected turn. However, the *flashing* green
arrow is virtually unused in the United States (and is not mentioned in the MUTCD). So
effectively, the FGA does not have a meaning yet --. I'm proposing that we give it one.

- - Dave
Jon Enslin
2004-10-29 14:12:58 UTC
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Post by Dave Barber
Post by Dave Barber
A really dangerous situation is at an intersection such as Cambridgeside Place /
Charles Street / First Street ... Cambridgeside Place is two-way, and changes
name to Charles Street when it crosses First Street, and becomes one-way the
wrong way (into the intersection). ..
This is one example of why I'd love to see a flashing green arrow used for the
left turn when you have to yield.
... A green arrow means protected turn. ...
I agree that a *steady* green arrow means a protected turn. However, the *flashing* green
arrow is virtually unused in the United States (and is not mentioned in the MUTCD). So
effectively, the FGA does not have a meaning yet --. I'm proposing that we give it one.
What's wrong with just the green light? My feeling is that a flashing arrow
would cause more confusion.

Jon
Mike Tantillo
2004-10-29 19:27:41 UTC
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Post by Dave Barber
Post by Dave Barber
A really dangerous situation is at an intersection such as Cambridgeside Place /
Charles Street / First Street ... Cambridgeside Place is two-way, and changes
name to Charles Street when it crosses First Street, and becomes one-way the
wrong way (into the intersection). ..
This is one example of why I'd love to see a flashing green arrow used for the
left turn when you have to yield.
... A green arrow means protected turn. ...
I agree that a *steady* green arrow means a protected turn. However, the *flashing* green
arrow is virtually unused in the United States (and is not mentioned in the MUTCD). So
effectively, the FGA does not have a meaning yet --. I'm proposing that we give it one.
green indicates that you have the right of way, thats why states are
experimenting with flashing yellow arrows...which mean use
caution...while yielding.
Post by Dave Barber
- - Dave
John S
2004-10-30 16:45:35 UTC
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Post by Dave Barber
Post by Dave Barber
A really dangerous situation is at an intersection such as Cambridgeside Place /
Charles Street / First Street ... Cambridgeside Place is two-way, and changes
name to Charles Street when it crosses First Street, and becomes one-way the
wrong way (into the intersection). ..
This is one example of why I'd love to see a flashing green arrow used for the
left turn when you have to yield.
... A green arrow means protected turn. ...
I agree that a *steady* green arrow means a protected turn. However, the *flashing* green
arrow is virtually unused in the United States (and is not mentioned in the MUTCD). So
effectively, the FGA does not have a meaning yet --. I'm proposing that we give it one.
The flashing turquoise arrow doesn't have a meaning yet either, but that doesn't mean we
should create a new indicator. The existing standards are clear and are not confusing when
they are implemented properly and consistently. Massachusetts (the location of the
intersection in question at the top of the thread) has a major problem with both of those
requirements, both for signals and signage.
Dave Barber
2004-10-31 14:04:40 UTC
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The flashing green arrow is virtually unused in the United States (and is not mentioned in
the MUTCD). So effectively, it does not have a meaning yet.
The flashing turquoise arrow doesn't have a meaning yet either, but that doesn't mean we
should create a new indicator.
I'm not trying to "use up" signal possibilities. Rather, I see a need for a permissive turn
indicator (even if for no reason other than the "yellow trap" problem). Meanwhile, the FGA is
not being used for anything. So I put them together.

- - - - - - - - - - - - -

When you boil it down, this flashing green arrow proposal had been facing two major veins of
contention:

A. Some folks say that we simply don't need a special symbol for the permissive left turn; they
believe that the green dot is satisfactory for indicating the permissive turn under all
possible circumstances.

B. Some folks favor having a special permissive-turn signal, but would not use the FGA: witness
the "Dallas display" and the Kittelson report which favors the flashing yellow arrow.

These may just be areas of permanent disagreement, such as those between Republicans and
Democrats.

- - Dave

http://home.earthlink.net/~tamivox/dave/traffic/fga/
John S
2004-10-31 16:21:11 UTC
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Post by Dave Barber
The flashing green arrow is virtually unused in the United States (and is not mentioned in
the MUTCD). So effectively, it does not have a meaning yet.
The flashing turquoise arrow doesn't have a meaning yet either, but that doesn't mean we
should create a new indicator.
I'm not trying to "use up" signal possibilities. Rather, I see a need for a permissive turn
indicator (even if for no reason other than the "yellow trap" problem). Meanwhile, the FGA is
not being used for anything. So I put them together.
Actually we already have a permissive turn indicator, and even Massachusetts has implemented it (in
some places.) For example, at the end of Hartwell Ave, Lexington, there is a traffic light at
Route 4. Traffic on Hartwell turning left has a green arrow during protected, then ball only
during permissive. One can not go straight because there is a DO NOT ENTER sign (one way opposite
direction). Right turns aren't a factor at this light either, because right turning traffic uses a
separate right lane with a YIELD sign.

Even in Massachusetts, standardized signals work well. When they're used.
Post by Dave Barber
- - - - - - - - - - - - -
When you boil it down, this flashing green arrow proposal had been facing two major veins of
A. Some folks say that we simply don't need a special symbol for the permissive left turn; they
believe that the green dot is satisfactory for indicating the permissive turn under all
possible circumstances.
B. Some folks favor having a special permissive-turn signal, but would not use the FGA: witness
the "Dallas display" and the Kittelson report which favors the flashing yellow arrow.
These may just be areas of permanent disagreement, such as those between Republicans and
Democrats.
- - Dave
http://home.earthlink.net/~tamivox/dave/traffic/fga/
The Etobian
2004-10-31 22:20:14 UTC
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Post by John S
Even in Massachusetts, standardized signals work well. When they're used.
Which is rare.
Monte Castleman
2004-10-28 15:01:18 UTC
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Post by Dave Barber
This is one example of why I'd love to see a flashing green arrow used for the
left turn when you have to yield. I preach a sermon on this subject at
What happens when someone from Ontario, where a flashing green means a
protected turn, visits?
--
--^\____
| / Monte Castleman, <<Spamfilter in Use>>
| / Bloomington, MN <<to email, remove the "q" from address>>
| |
| *| Visit my Minnesota Highways Page:
|_____\ http://home.earthlink.net/~northstarhighways
Jeff W
2004-10-28 21:46:33 UTC
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Post by Monte Castleman
Post by Dave Barber
This is one example of why I'd love to see a flashing green arrow used for the
left turn when you have to yield. I preach a sermon on this subject at
What happens when someone from Ontario, where a flashing green means a
protected turn, visits?
Probably the same thing when they approaching a blinking yellow
emergency signal. Stop and cause an accident.

And since when are you yielding on a green arrow!?!?!?!? That's
insane.
You know what it probably is.
When making a right turn, you turn into the rightmost lane.
When making a left turn, you turn into any available lane.
Meaning both ways can technically turn at once, if your around a place
where people have a clue or do this daily. I try my best, but there's
always on person on a cellphone typically, that makes a right and
stays on an angle accross 3 lanes(without the signal too).

What they need, instead of a "new" type of light, is to paint some
skip lines to make traffic do this. maybe a sign or two so you dont'
freak out when turning.
J Mello
2004-10-29 14:11:12 UTC
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Post by Jeff W
Post by Monte Castleman
Post by Dave Barber
This is one example of why I'd love to see a flashing green arrow used for the
left turn when you have to yield. I preach a sermon on this subject at
What happens when someone from Ontario, where a flashing green means a
protected turn, visits?
Probably the same thing when they approaching a blinking yellow
emergency signal. Stop and cause an accident.
And since when are you yielding on a green arrow!?!?!?!? That's
insane.
You know what it probably is.
When making a right turn, you turn into the rightmost lane.
When making a left turn, you turn into any available lane.
Actually, you are ALWAYS supposed to turn into the closest lane.

-JMello
Jeff W
2004-10-29 20:59:51 UTC
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Post by J Mello
Post by Jeff W
Post by Monte Castleman
Post by Dave Barber
This is one example of why I'd love to see a flashing green arrow used for the
left turn when you have to yield. I preach a sermon on this subject at
What happens when someone from Ontario, where a flashing green means a
protected turn, visits?
Probably the same thing when they approaching a blinking yellow
emergency signal. Stop and cause an accident.
And since when are you yielding on a green arrow!?!?!?!? That's
insane.
You know what it probably is.
When making a right turn, you turn into the rightmost lane.
When making a left turn, you turn into any available lane.
Actually, you are ALWAYS supposed to turn into the closest lane.
-JMello
The Florida handbook has it separated on how I said it, but that's
pretty much the same as closest lane. Unless your by yourself or on a
protected turn on a large street, then you can at least go right over
to the right.

I think in this example, they NEED some skiplines and a sign, Not a
newfangled type of light.
Timothy J. Lee
2004-10-31 16:23:06 UTC
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Post by J Mello
Post by Jeff W
When making a right turn, you turn into the rightmost lane.
When making a left turn, you turn into any available lane.
Actually, you are ALWAYS supposed to turn into the closest lane.
Not in all jurisdictions. Some places, like California, allow left
turners to turn into any lawfully available lane (although right turners
are required to turn as close as practicable to the right hand curb or
edge of the roadway).

If driving in a place where one does not know whether turning traffic
is required to turn into the inside lane, it is safest to turn into the
inside lane, but not assume that others will do so (even if there is a
law, it may not be obeyed).
--
------------------------------------------------------------------------
Timothy J. Lee
Unsolicited bulk or commercial email is not welcome.
No warranty of any kind is provided with this message.
Keith
2004-10-29 02:00:48 UTC
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Post by Monte Castleman
Post by Dave Barber
This is one example of why I'd love to see a flashing green arrow used for the
left turn when you have to yield. I preach a sermon on this subject at
What happens when someone from Ontario, where a flashing green means a
protected turn, visits?
Fuck those Ontario communists.
Dave Barber
2004-10-29 13:44:12 UTC
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Post by Monte Castleman
Post by Dave Barber
This is one example of why I'd love to see a flashing green arrow used for the
left turn when you have to yield. I preach a sermon on this subject at
What happens when someone from Ontario, where a flashing green means a
protected turn, visits?
A sign saying "YIELD ON FLASHING ARROW" will inform the unfamiliar, wherever
they're from; a sample is on my flashing arrow page.

Of course, standardizing highway rules worldwide would work, too, but that is a
*tall* order.

- - Dave
Jeff nor Lisa
2004-10-29 18:14:23 UTC
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Post by Dave Barber
This is one example of why I'd love to see a flashing green arrow used for the
left turn when you have to yield. I preach a sermon on this subject at
AFAIK, a flashing signal of a color means _greater_ freedom than
the steady version of a color. This is both highway and railroad
signalling.

For instance, a steady red means stop and stay while a flashing
red means stop then proceed when clear. A steady yellow means
prepare for red light and proceed with caution while a blinking yellow
means only proceed with caution.

The problem with a blinking green is that green is already a signal
without restrictions. A blinking green would mean some sort of
restriction on unlimited proceed, perhaps changing lanes up ahead
(this is not in actual practice for roads.)


If you are seeking a turn signal that requires motorists to yield,
I would suggest a blinking red arrow or a blinking yellow arrow.
But I don't know if these are standardized aspects.


BTW, someone mentioned Penna does not use red arrows. It does
now, though they are rare.
Mike Tantillo
2004-10-30 01:37:53 UTC
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Post by Jeff nor Lisa
Post by Dave Barber
This is one example of why I'd love to see a flashing green arrow used for the
left turn when you have to yield. I preach a sermon on this subject at
AFAIK, a flashing signal of a color means _greater_ freedom than
the steady version of a color. This is both highway and railroad
signalling.
For instance, a steady red means stop and stay while a flashing
red means stop then proceed when clear. A steady yellow means
prepare for red light and proceed with caution while a blinking yellow
means only proceed with caution.
The problem with a blinking green is that green is already a signal
without restrictions. A blinking green would mean some sort of
restriction on unlimited proceed, perhaps changing lanes up ahead
(this is not in actual practice for roads.)
If you are seeking a turn signal that requires motorists to yield,
I would suggest a blinking red arrow or a blinking yellow arrow.
But I don't know if these are standardized aspects.
Blinking red arrow would mean proceed with your left turn after a full
stop. I've seen these (or the equivalent....VA doesn't use red arrows
so a flashing red ball over a left turn lane with flashing yellow
balls over the through lanes is basically a flashing red arrow in many
other states) at intersections with flashers and they want to
reiterate that left turning traffic does not have the right of way.

Flashing yellow arrow is what some places (like Alexandria, VA) have
been using. It is "less restrictive" then a steady yellow (prepare to
stop and wait), but more restrictive then a steady green (proceed).
The flashing yellow "in between" means "proceed with caution"...much
like a flashing yellow ball, although part of caution means yielding
to oncoming traffic.
Post by Jeff nor Lisa
BTW, someone mentioned Penna does not use red arrows. It does
now, though they are rare.
Alan Hamilton
2004-10-30 03:14:04 UTC
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Post by Mike Tantillo
The flashing yellow "in between" means "proceed with caution"...much
like a flashing yellow ball, although part of caution means yielding
to oncoming traffic.
And that's one reason I don't like using a flashing yellow arrow for
this purpose. A flashing yellow means you do have the right of way
and don't need to stop.
--
/
/ * / Alan Hamilton
* * ***@arizonaroads.com

Arizona Roads -- http://www.arizonaroads.com
Dave Barber
2004-10-30 14:39:42 UTC
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... A flashing yellow means you do have the right of way and don't need
to stop.
If you're turning left, and oncoming thru traffic has a flashing yellow
signal, you'd better yield. Also you must yield to pedestrians when
turning either left or right on flashing yellow.

- - Dave

http://home.earthlink.net/~tamivox/dave/traffic/fga/
Dave Barber
2004-10-30 14:31:51 UTC
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Post by Jeff nor Lisa
Post by Dave Barber
This is one example of why I'd love to see a flashing green arrow used for the
left turn when you have to yield.
AFAIK, a flashing signal of a color means _greater_ freedom than
the steady version of a color. This is both highway and railroad signalling.
My view on this is that the flashing version of a signal is the *weakened* version
of it. (Rationale: the light is on only half the time, so it must have less
meaning.)

Red lights are fundamentally restrictive. A flashing red light is less so than a
steady red light, because on the steady red you must wait until it turns green, but
after you stop on the flashing red you can proceed as soon as safety permits.

A steady yellow warns of an upcoming restriction, namely a red light, while a
flashing yellow does not mean much at all: although it tells you to be "cautious",
you're always supposed to be cautious when driving.

Green lights are fundamentally permissive. The steady green arrow indicates a
protected left turn (no yielding necessary), while the flashing arrow I've suggested
is weaker, because it only means a permissive left turn (you have to yield).
Post by Jeff nor Lisa
If you are seeking a turn signal that requires motorists to yield, I would suggest
a blinking red arrow or a blinking yellow arrow.
I completely agree with using a flashing red arrow to mean stop, yield and go.

- - Dave

http://home.earthlink.net/~tamivox/dave/traffic/fga/
Mike Tantillo
2004-10-29 19:26:07 UTC
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Post by Dave Barber
A really dangerous situation is at an intersection such as Cambridgeside Place /
Charles Street / First Street ... Cambridgeside Place is two-way, and changes
name to Charles Street when it crosses First Street, and becomes one-way the
wrong way (into the intersection). First Street is two-way. When Cambridgeside
gets the green, rather than a green ball, it gets a green left arrow and a green
right arrow, indicating you can turn left or right, but not straight.
Unfortunately, Charles Street has the green light at the same time. So, you
have a left arrow, which in any other state means you have a protected left, but
you also have opposing traffic, that you must yield the right of way to, but no
indication of the oposing traffic ...
This is one example of why I'd love to see a flashing green arrow used for the
left turn when you have to yield. I preach a sermon on this subject at
Actually, various state DOT's are experimenting with a flashing yellow
arrow in place of the green ball/green arrow "doghouse" signals for
protected/permissive turns. When the light is red arrow, no turns.
steady yellow, its about to turn to red arrow. Green arrow,
protected, you can go. flashing yellow arrow, you can go, but must
yield to oncoming traffic.

Supposidly some research has shown that drivers understand the
flashing yellow arrow/green arrow better then the green ball/green
arrow for protected/permissive. The city of Alexandria, VA has
experimented quite extensively and is now replacing all signals with
the flashing yellow arrow. NCDOT is experimenting with this as well,
they either will or already have installed one of these at the
intersection of New Bern Ave and Wake Med Center in Raleigh.

As with all new signs, new signals, etc, there is going to be a
"learning curve" before the public gets used to it. but then once
people are used to it, it becomes normal.
Post by Dave Barber
http://home.earthlink.net/~tamivox/dave/traffic/fga/
- - Dave
Brian Purcell
2004-10-30 15:20:30 UTC
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Post by Mike Tantillo
As with all new signs, new signals, etc, there is going to be a
"learning curve" before the public gets used to it. but then once
people are used to it, it becomes normal.
If that was true, then we wouldn't have these problems to begin with. ;)

--Brian Purcell
San Antonio, Texas, USA
mailto:***@texhwyman.com
http://www.texhwyman.com
Jeff W
2004-10-30 23:58:17 UTC
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Post by Mike Tantillo
Post by Dave Barber
A really dangerous situation is at an intersection such as Cambridgeside Place /
Charles Street / First Street ... Cambridgeside Place is two-way, and changes
name to Charles Street when it crosses First Street, and becomes one-way the
wrong way (into the intersection). First Street is two-way. When Cambridgeside
gets the green, rather than a green ball, it gets a green left arrow and a green
right arrow, indicating you can turn left or right, but not straight.
Unfortunately, Charles Street has the green light at the same time. So, you
have a left arrow, which in any other state means you have a protected left, but
you also have opposing traffic, that you must yield the right of way to, but no
indication of the oposing traffic ...
This is one example of why I'd love to see a flashing green arrow used for the
left turn when you have to yield. I preach a sermon on this subject at
Actually, various state DOT's are experimenting with a flashing yellow
arrow in place of the green ball/green arrow "doghouse" signals for
protected/permissive turns. When the light is red arrow, no turns.
steady yellow, its about to turn to red arrow. Green arrow,
protected, you can go. flashing yellow arrow, you can go, but must
yield to oncoming traffic.
Supposidly some research has shown that drivers understand the
flashing yellow arrow/green arrow better then the green ball/green
arrow for protected/permissive. The city of Alexandria, VA has
experimented quite extensively and is now replacing all signals with
the flashing yellow arrow. NCDOT is experimenting with this as well,
they either will or already have installed one of these at the
intersection of New Bern Ave and Wake Med Center in Raleigh.
As with all new signs, new signals, etc, there is going to be a
"learning curve" before the public gets used to it. but then once
people are used to it, it becomes normal.
Post by Dave Barber
http://home.earthlink.net/~tamivox/dave/traffic/fga/
- - Dave
I'm not buying that. There's plenty of flashing yellows around, and
the only people stopping or pretending they're about to yeild have
canadian tags.
It's like the dead signals that are supposed to be treated as 4-way
stops, and only 5% of the people do that, no matter how many times
they say it on the radio every five minutes, no signal means stop.

Second, I love the counties that almost 100% of the signals are
protected lefts, i'm not too fond of yield on greens, but I dont' see
any examples or instances around where you need a brand new type of
signal. It's as redunant as the sign I saw that reads, "Move on Green
Only".
Mike Tantillo
2004-10-31 18:07:51 UTC
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Post by Jeff W
Post by Mike Tantillo
Post by Dave Barber
A really dangerous situation is at an intersection such as Cambridgeside Place /
Charles Street / First Street ... Cambridgeside Place is two-way, and changes
name to Charles Street when it crosses First Street, and becomes one-way the
wrong way (into the intersection). First Street is two-way. When Cambridgeside
gets the green, rather than a green ball, it gets a green left arrow and a green
right arrow, indicating you can turn left or right, but not straight.
Unfortunately, Charles Street has the green light at the same time. So, you
have a left arrow, which in any other state means you have a protected left, but
you also have opposing traffic, that you must yield the right of way to, but no
indication of the oposing traffic ...
This is one example of why I'd love to see a flashing green arrow used for the
left turn when you have to yield. I preach a sermon on this subject at
Actually, various state DOT's are experimenting with a flashing yellow
arrow in place of the green ball/green arrow "doghouse" signals for
protected/permissive turns. When the light is red arrow, no turns.
steady yellow, its about to turn to red arrow. Green arrow,
protected, you can go. flashing yellow arrow, you can go, but must
yield to oncoming traffic.
Supposidly some research has shown that drivers understand the
flashing yellow arrow/green arrow better then the green ball/green
arrow for protected/permissive. The city of Alexandria, VA has
experimented quite extensively and is now replacing all signals with
the flashing yellow arrow. NCDOT is experimenting with this as well,
they either will or already have installed one of these at the
intersection of New Bern Ave and Wake Med Center in Raleigh.
As with all new signs, new signals, etc, there is going to be a
"learning curve" before the public gets used to it. but then once
people are used to it, it becomes normal.
Post by Dave Barber
http://home.earthlink.net/~tamivox/dave/traffic/fga/
- - Dave
I'm not buying that. There's plenty of flashing yellows around, and
the only people stopping or pretending they're about to yeild have
canadian tags.
It's like the dead signals that are supposed to be treated as 4-way
stops, and only 5% of the people do that, no matter how many times
they say it on the radio every five minutes, no signal means stop.
Second, I love the counties that almost 100% of the signals are
protected lefts, i'm not too fond of yield on greens, but I dont' see
any examples or instances around where you need a brand new type of
signal. It's as redunant as the sign I saw that reads, "Move on Green
Only".
As you state, many drivers are morons and don't know the rules. For
the moron-type, supposidly the flashing arrow gets the message across
better then the green ball/green arrow thats not lit combo.

I'm assuming this is because when people see the flashing arrow, they
err on the side of caution and are more likely to yield, either
because they know thats what you do at flashing yellow arrows, or
because they've never seen one before. But supposidly people in
Alexandria have had no problem adapting to the flashing arrow.

I too was reluctant to the yellow arrow flashing when I first heard of
it...but I embraced the concept when I saw it in action. People in
general are resistant to change, but when you implement the ghange,
peopel say "why didn't we do this much sooner?". This might be one of
those examples.
The Etobian
2004-10-31 22:20:14 UTC
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Post by Mike Tantillo
As you state, many drivers are morons and don't know the rules.
Somewhat off-topic, but in response to the statement above:

You're driving in Taunton, Mass. You are in the left turn lane,
beyond the stop line, waiting to make a left turn. Your light turns
yellow then red. Is it safe to make left turn at that point?
Brian Purcell
2004-10-31 17:05:46 UTC
Reply
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Post by Mike Tantillo
Actually, various state DOT's are experimenting with a flashing yellow
arrow in place of the green ball/green arrow "doghouse" signals for
protected/permissive turns. When the light is red arrow, no turns.
steady yellow, its about to turn to red arrow. Green arrow,
protected, you can go. flashing yellow arrow, you can go, but must
yield to oncoming traffic.
Supposidly some research has shown that drivers understand the
flashing yellow arrow/green arrow better then the green ball/green
arrow for protected/permissive. The city of Alexandria, VA has
experimented quite extensively and is now replacing all signals with
the flashing yellow arrow. NCDOT is experimenting with this as well,
they either will or already have installed one of these at the
intersection of New Bern Ave and Wake Med Center in Raleigh.
Germany uses the flashing yellow arrow at some intersections to
indicate a permissive left turn.

--Brian Purcell
San Antonio, Texas, USA
mailto:***@texhwyman.com
http://www.texhwyman.com
Brian Purcell
2004-10-31 17:15:11 UTC
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Switzerland uses a flashing yellow triangle to indicate a permissive
left (i.e. left turn must yield).

Examples of Switzerland's and Germany's permissive left signals are
the first two items on this page:
http://homepages.cwi.nl/~dik/english/traffic/signals/vl-s.html

--Brian Purcell
San Antonio, Texas, USA
mailto:***@texhwyman.com
http://www.texhwyman.com
Some One
2004-08-17 22:18:52 UTC
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Post by Lepidopteran
a red light (ball/circular) lit at the same time as a green left- or
right-turn arrow, when the traffic signal head has only 3 sections?
6 days ago at the corner of Haggerty and Richardson Roads on the border of
Commerce and West Bloomfield Townships in southeast Michigan. I think
there is also one a few blocks further west at Richardson and Union Lake
Roads.
Nick C
2004-08-17 23:00:34 UTC
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They're not too hard to find in Pittsburgh, especially on Washington Road
near the Allegheny/Washington County line.
Post by Lepidopteran
a red light (ball/circular) lit at the same time as a green left- or
right-turn arrow, when the traffic signal head has only 3 sections? I
saw a left-turn signal that did this a few weeks ago in a western
suburb of Philadelphia.
The purpose of having a red light lit along with a green turning arrow
is to prevent confusion by telling other traffic going in the same
direction that they still must remain stopped. Indeed, one can see
this all the time with 5-section signals (inline or doghouse) and once
in a while with a 4-section. But except for that one in Pennsylvania,
I don't remember the last time I saw that sequence on a 3-section
signal.
One reason you don't find the r-ga on a 3-section anymore is that many
states have red arrows along with the yellow and green ones, and a red
arrow lit with a green arrow on the same signal head would be
meaningless. Or perhaps it's just a holdover from a time when arrow
indications were new, and motorists were not expected to understand
that only the turning traffic could proceed. Indeed, how many of us
today still jolt forward a bit when the left-only arrow comes on while
we're still red?
Another reason is that today's traffic signal controllers are smarter
than those in years past. Consider this one sequence for a right-turn
GREEN ARROW, along with green on through road
YELLOW BALL, along with yellow on through road
RED BALL with GREEN ARROW, since cross-traffic to the right now has a
protected left. When that protected left ended, the arrow just
disappeared.
In a system installed today, that right-turn signal would "know" in
advance that the cross-traffic is getting a protected left, and
wouldn't even turn yellow in the first place. It would only turn
yellow when that protected left goes to a yellow arrow.
Still another reason is that many of today's protected left turn
signals are not visible from the rest of the traffic flow. This is
typically done by using "louvers" (those thin metal vertical ribs
under the signal visor that make the lens look like a Ruffles potato
chip) or with "programmed visibility" lenses made by 3M.
For a really odd situation, how about a red ball on with a
straight-through arrow? Someone in this newsgroup once posted of a
mutant traffic signal in Massachusetts somewhere that did indeed have
this sequence! He said that the only time the red light was dark was
when the yellow light was lit. (The MUTCD also prohibits yellow or
red straight-through arrows.)
Marc Fannin
2004-08-18 19:44:14 UTC
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Post by Lepidopteran
a red light (ball/circular) lit at the same time as a green left- or
right-turn arrow, when the traffic signal head has only 3 sections?
http://www.roadfan.com/neash.html
(Photo from four years ago, signal still like that IIRC)
Post by Lepidopteran
Another reason is that today's traffic signal controllers are smarter
than those in years past. Consider this one sequence for a right-turn
GREEN ARROW, along with green on through road
YELLOW BALL, along with yellow on through road
RED BALL with GREEN ARROW, since cross-traffic to the right now has a
protected left. When that protected left ended, the arrow just
disappeared.
In a system installed today, that right-turn signal would "know" in
advance that the cross-traffic is getting a protected left, and
wouldn't even turn yellow in the first place.
Theoretically it wouldn't, and I know of a place where this happens,
but it sets up a trap for left-turn traffic already in the
intersection facing the other way as the traffic facing the right
arrow. (I know, it's happened to me. In the intersection where it
happened the right-turn doghouse now turns red for the length of the
all-red interval before the green right arrow comes on). Of course if
the road with the continuous right arrow is the terminal road in a "T"
intersection, the problem goes away.

________________________________________________________________________
Marc Fannin|***@kent.edu or @hotmail.com| http://www.roadfan.com/
Arrow
2004-08-19 08:22:28 UTC
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Post by Lepidopteran
a red light (ball/circular) lit at the same time as a green left- or
right-turn arrow, when the traffic signal head has only 3 sections? I
saw a left-turn signal that did this a few weeks ago in a western
suburb of Philadelphia.
The purpose of having a red light lit along with a green turning arrow
is to prevent confusion by telling other traffic going in the same
direction that they still must remain stopped. Indeed, one can see
this all the time with 5-section signals (inline or doghouse) and once
in a while with a 4-section. But except for that one in Pennsylvania,
I don't remember the last time I saw that sequence on a 3-section
signal.
One reason you don't find the r-ga on a 3-section anymore is that many
states have red arrows along with the yellow and green ones, and a red
arrow lit with a green arrow on the same signal head would be
meaningless. Or perhaps it's just a holdover from a time when arrow
indications were new, and motorists were not expected to understand
that only the turning traffic could proceed. Indeed, how many of us
today still jolt forward a bit when the left-only arrow comes on while
we're still red?
Another reason is that today's traffic signal controllers are smarter
than those in years past. Consider this one sequence for a right-turn
GREEN ARROW, along with green on through road
YELLOW BALL, along with yellow on through road
RED BALL with GREEN ARROW, since cross-traffic to the right now has a
protected left. When that protected left ended, the arrow just
disappeared.
In a system installed today, that right-turn signal would "know" in
advance that the cross-traffic is getting a protected left, and
wouldn't even turn yellow in the first place. It would only turn
yellow when that protected left goes to a yellow arrow.
Still another reason is that many of today's protected left turn
signals are not visible from the rest of the traffic flow. This is
typically done by using "louvers" (those thin metal vertical ribs
under the signal visor that make the lens look like a Ruffles potato
chip) or with "programmed visibility" lenses made by 3M.
For a really odd situation, how about a red ball on with a
straight-through arrow? Someone in this newsgroup once posted of a
mutant traffic signal in Massachusetts somewhere that did indeed have
this sequence! He said that the only time the red light was dark was
when the yellow light was lit. (The MUTCD also prohibits yellow or
red straight-through arrows.)
They're more common than you'd think. I can think of a few, like in
Washington, DC, 26th St NW going south into Pennsylvania Ave since 26th
past Penn is one-way the wrong way. In Rochester, NY, there's one at the
intersection of Byron and Clinton Aves simply because you physically
can't go straight. One light for left turns, another separate light for
right turns.

Of course, I can't say for certain that both these examples involve
balls for red and yellow, so..

--
Justin P.
Mitsguy2001
2004-08-24 02:25:14 UTC
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Post by Lepidopteran
For a really odd situation, how about a red ball on with a
straight-through arrow? Someone in this newsgroup once posted of a
mutant traffic signal in Massachusetts somewhere that did indeed have
this sequence! He said that the only time the red light was dark was
when the yellow light was lit. (The MUTCD also prohibits yellow or
red straight-through arrows.)
That poster was me. And, the signal in question is in Cambridge, MA, at the
intersection of Memorial Drive (MA 3) and Amesbury Street. This is at the
Hyatt Regency Hotel, and just west of MIT. The intersection is a horrible
design. It has a protected-only left turn from Memorial Drive EB (MA 3 SB) to
Amesbury Street NB (there are no signs referring to Amesbury Street, but that
is its name on maps). Most of the time, EB Mem Drive (MA 3 SB) has a red ball,
with a green straight arrow, indicating that you may go straight, but not left
(Mem Drive runs along the Charles River, so a right turn would dunk you into
the river). When you get the protected left turn phase, the red ball goes
away, and you get a green straight arrow, and a green left arrow. The
intersection also has a sign saying "Left Turn on Left Green Arrow only" (or
something like that, I haven't been down there in a while). That sign appears
at several intersections in Cambridge. It makes no sense. The other problem
with the intersection is that it has a protected-only left turn, but no left
turn lane! If anyone wants to turn left at the intersection, you must block
the left through lane of Mem Drive! That means, Mem Drive through traffic is
reduced to a single lane if even a single car wants to turn left at that
intersction! It is ridiculous. I would never turn left there. I'd either
turn left a block earlier at Vassar, or a block later at Audrey. One other key
detail is that you have to wait a VERY long time to get your left turn arrow to
turn left onto Amesbury. Many people just ignore the light, and turn left when
there is a gap in traffic. It's non-standard setup is even more dangerous
given that the intersection serves a hotel, and the MIT campus, and has a lot
of out of town drivers who are not used to the setup.
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