When two-light traffic signals were still somewhat common in the US (bit
before my time..) does anyone know which arrangement was more common,
for all signals to go dark in both directions as a replacement for the
missing yellow, or for red and green to come on in the respective
direction in lieu of a yellow in that direction.

Or was it just municipality preference. I've seen ad copy from the time
from signal manufacturers advertising both schemes so wasn't sure if one
was more common than the other in practice, asking for a friend who's
building a diorama

On 5/31/2021 1:24 PM, bitrex wrote:
> When two-light traffic signals were still somewhat common in the US (bit before
> my time..) does anyone know which arrangement was more common, for all signals
> to go dark in both directions as a replacement for the missing yellow, or for
> red and green to come on in the respective direction in lieu of a yellow in
> that direction.
>
> Or was it just municipality preference. I've seen ad copy from the time from
> signal manufacturers advertising both schemes so wasn't sure if one was more
> common than the other in practice, asking for a friend who's building a diorama

From:

<https://www.scienceabc.com/innovation/ready-steady-go-the-evolution-of-traffic-lights.html#the-first-four-way-and-three-colour-traffic-lights>

"The first electric traffic light had only red and green lights; it did not
have a yellow light like modern-day traffic signals. Instead of a yellow light,
it had a buzzer sound that was used to indicate that the signal would be
changing soon."

Growing up, we had a variety of "traffic signals" -- including *single*
lights. Note that a light can also FLASH -- which conveys additional meaning.

E.g., here, our left-turn arrows flash yellow while oncoming traffic
has a solid green (we use a "lagging left" strategy). So, you can
legally enter the intersection (for a left turn) and execute that turn
*if* conditions permit.

On 5/31/2021 5:09 PM, Don Y wrote:
> On 5/31/2021 1:24 PM, bitrex wrote:
>> When two-light traffic signals were still somewhat common in the US
>> (bit before my time..) does anyone know which arrangement was more
>> common, for all signals to go dark in both directions as a replacement
>> for the missing yellow, or for red and green to come on in the
>> respective direction in lieu of a yellow in that direction.
>>
>> Or was it just municipality preference. I've seen ad copy from the
>> time from signal manufacturers advertising both schemes so wasn't sure
>> if one was more common than the other in practice, asking for a friend
>> who's building a diorama
>
> From:
>
> <https://www.scienceabc.com/innovation/ready-steady-go-the-evolution-of-traffic-lights.html#the-first-four-way-and-three-colour-traffic-lights>
>
>
> "The first electric traffic light had only red and green lights; it did
> not have a yellow light like modern-day traffic signals. Instead of a
> yellow light, it had a buzzer sound that was used to indicate that the
> signal would be changing soon."

Well the first is pretty long ago. As I understand it two-lights were
still being used in some smaller municipalities well into the 60s, even
70s maybe.

> Growing up, we had a variety of "traffic signals" -- including *single*
> lights.  Note that a light can also FLASH -- which conveys additional
> meaning.

The intersection in the center of the town I grew up in had a hanging
flashing red/amber lamp well into the 70s until it was replaced with
full signals around the year I was born. Second-hand info, obviously.

> E.g., here, our left-turn arrows flash yellow while oncoming traffic
> has a solid green (we use a "lagging left" strategy).  So, you can
> legally enter the intersection (for a left turn) and execute that turn
> *if* conditions permit.

There are a few signals like this in MA but they're currently rare. More
common in Rhode Island.

Usually you're either fortunate enough to have a fully protected green
arrow in a dedicated left turn lane that then sequences back to solid
yellow arrow and red, or yield on green and fight the yellow trap at
"less congested" intersections with a single lane of traffic.

Sometimes the green arrow sequences to solid green at edge-case
intersections.

There's always some confusion as to whether one can turn on a red arrow;
at least in MA a red arrow is no different than a solid red signal for
your lane (just implies thee are multiple lights for your direction of
travel that are timed differently) so you can turn on a red arrow any
time you can turn on a solid red.

On 5/31/2021 5:09 PM, Don Y wrote:
> On 5/31/2021 1:24 PM, bitrex wrote:
>> When two-light traffic signals were still somewhat common in the US
>> (bit before my time..) does anyone know which arrangement was more
>> common, for all signals to go dark in both directions as a replacement
>> for the missing yellow, or for red and green to come on in the
>> respective direction in lieu of a yellow in that direction.
>>
>> Or was it just municipality preference. I've seen ad copy from the
>> time from signal manufacturers advertising both schemes so wasn't sure
>> if one was more common than the other in practice, asking for a friend
>> who's building a diorama
>
> From:
>
> <https://www.scienceabc.com/innovation/ready-steady-go-the-evolution-of-traffic-lights.html#the-first-four-way-and-three-colour-traffic-lights>
>
>
> "The first electric traffic light had only red and green lights; it did
> not have a yellow light like modern-day traffic signals. Instead of a
> yellow light, it had a buzzer sound that was used to indicate that the
> signal would be changing soon."
>
> Growing up, we had a variety of "traffic signals" -- including *single*
> lights.  Note that a light can also FLASH -- which conveys additional
> meaning.
>
> E.g., here, our left-turn arrows flash yellow while oncoming traffic
> has a solid green (we use a "lagging left" strategy).  So, you can
> legally enter the intersection (for a left turn) and execute that turn
> *if* conditions permit.

Here's an ad for a two-light signal from 1944, this one has a brief
all-dark period both directions in lieu of a yellow. Seems dangerous,
maybe the switched over to green-red flash at night:

<http://www.kbrhorse.net/sigpics2/darley01.jpg>

I know in olden times some three-light signals also changed to yellow in
unison, prior to swapping green-red directions.

Hanging red/amber single-light flashers seem unpopular in my area now,
probably due to maintenance cost. Most seem to have been replaced by
something like a solar powered STOP sign with red LEDs for the side
route, and the same but CAUTION for the main route.

On Monday, May 31, 2021 at 3:08:19 PM UTC-7, bitrex wrote:
> On 5/31/2021 5:09 PM, Don Y wrote:
> > On 5/31/2021 1:24 PM, bitrex wrote:
> >> When two-light traffic signals were still somewhat common in the US
> >> (bit before my time..) does anyone know which arrangement was more
> >> common, for all signals to go dark in both directions as a replacement
> >> for the missing yellow, or for red and green to come on in the
> >> respective direction in lieu of a yellow in that direction.
> >>
> >> Or was it just municipality preference. I've seen ad copy from the
> >> time from signal manufacturers advertising both schemes so wasn't sure
> >> if one was more common than the other in practice, asking for a friend
> >> who's building a diorama
> >
> > From:
> >
> > <https://www.scienceabc.com/innovation/ready-steady-go-the-evolution-of-traffic-lights.html#the-first-four-way-and-three-colour-traffic-lights>
> >
> >
> > "The first electric traffic light had only red and green lights; it did
> > not have a yellow light like modern-day traffic signals. Instead of a
> > yellow light, it had a buzzer sound that was used to indicate that the
> > signal would be changing soon."
> Well the first is pretty long ago. As I understand it two-lights were
> still being used in some smaller municipalities well into the 60s, even
> 70s maybe.
> > Growing up, we had a variety of "traffic signals" -- including *single*
> > lights. Note that a light can also FLASH -- which conveys additional
> > meaning.
> The intersection in the center of the town I grew up in had a hanging
> flashing red/amber lamp well into the 70s until it was replaced with
> full signals around the year I was born. Second-hand info, obviously.
> > E.g., here, our left-turn arrows flash yellow while oncoming traffic
> > has a solid green (we use a "lagging left" strategy). So, you can
> > legally enter the intersection (for a left turn) and execute that turn
> > *if* conditions permit.
> There are a few signals like this in MA but they're currently rare. More
> common in Rhode Island.
>
> Usually you're either fortunate enough to have a fully protected green
> arrow in a dedicated left turn lane that then sequences back to solid
> yellow arrow and red, or yield on green and fight the yellow trap at
> "less congested" intersections with a single lane of traffic.
>
> Sometimes the green arrow sequences to solid green at edge-case
> intersections.
>
> There's always some confusion as to whether one can turn on a red arrow;
> at least in MA a red arrow is no different than a solid red signal for
> your lane (just implies thee are multiple lights for your direction of
> travel that are timed differently) so you can turn on a red arrow any
> time you can turn on a solid red.

And flashing red?

Here, in San Mateo, at night, El Camino Real (main road in spanish) is always flashing red. I assume it's merger beware. Ongoing traffic don't even slow down.

On 5/31/2021 3:19 PM, Ed Lee wrote:
> On Monday, May 31, 2021 at 3:08:19 PM UTC-7, bitrex wrote:
>> On 5/31/2021 5:09 PM, Don Y wrote:
>>> On 5/31/2021 1:24 PM, bitrex wrote:
>>>> When two-light traffic signals were still somewhat common in the US
>>>> (bit before my time..) does anyone know which arrangement was more
>>>> common, for all signals to go dark in both directions as a
>>>> replacement for the missing yellow, or for red and green to come on in
>>>> the respective direction in lieu of a yellow in that direction.
>>>>
>>>> Or was it just municipality preference. I've seen ad copy from the
>>>> time from signal manufacturers advertising both schemes so wasn't
>>>> sure if one was more common than the other in practice, asking for a
>>>> friend who's building a diorama
>>>
>>> From:
>>>
>>> <https://www.scienceabc.com/innovation/ready-steady-go-the-evolution-of-traffic-lights.html#the-first-four-way-and-three-colour-traffic-lights>
>>>
>>>
>>>
>>>
"The first electric traffic light had only red and green lights; it did
>>> not have a yellow light like modern-day traffic signals. Instead of a
>>> yellow light, it had a buzzer sound that was used to indicate that the
>>> signal would be changing soon."
>> Well the first is pretty long ago. As I understand it two-lights were
>> still being used in some smaller municipalities well into the 60s, even
>> 70s maybe.
>>> Growing up, we had a variety of "traffic signals" -- including *single*
>>> lights. Note that a light can also FLASH -- which conveys additional
>>> meaning.
>> The intersection in the center of the town I grew up in had a hanging
>> flashing red/amber lamp well into the 70s until it was replaced with full
>> signals around the year I was born. Second-hand info, obviously.
>>> E.g., here, our left-turn arrows flash yellow while oncoming traffic has
>>> a solid green (we use a "lagging left" strategy). So, you can legally
>>> enter the intersection (for a left turn) and execute that turn *if*
>>> conditions permit.
>> There are a few signals like this in MA but they're currently rare. More
>> common in Rhode Island.
>>
>> Usually you're either fortunate enough to have a fully protected green
>> arrow in a dedicated left turn lane that then sequences back to solid
>> yellow arrow and red, or yield on green and fight the yellow trap at "less
>> congested" intersections with a single lane of traffic.
>>
>> Sometimes the green arrow sequences to solid green at edge-case
>> intersections.
>>
>> There's always some confusion as to whether one can turn on a red arrow;
>> at least in MA a red arrow is no different than a solid red signal for
>> your lane (just implies thee are multiple lights for your direction of
>> travel that are timed differently) so you can turn on a red arrow any time
>> you can turn on a solid red.
>
> And flashing red?
>
> Here, in San Mateo, at night, El Camino Real (main road in spanish) is
> always flashing red. I assume it's merger beware. Ongoing traffic don't
> even slow down.

A flashing red light is interpreted as a stop sign; come to a complete
stop, proceed when safe to do so.

The pedestrian crossings that we have (NOT at intersections but, rather,
between intersections) will signal solid red to stop all traffic while
the pedestrians are given time to cross. This transitions to blinking red
to alert drivers to check for laggers before proceeding. Then, the flashing
disappears (there is no "green" light).

On 5/31/2021 3:08 PM, bitrex wrote:
> On 5/31/2021 5:09 PM, Don Y wrote:
>> On 5/31/2021 1:24 PM, bitrex wrote:
>>> When two-light traffic signals were still somewhat common in the US (bit
>>> before my time..) does anyone know which arrangement was more common, for
>>> all signals to go dark in both directions as a replacement for the missing
>>> yellow, or for red and green to come on in the respective direction in lieu
>>> of a yellow in that direction.
>>>
>>> Or was it just municipality preference. I've seen ad copy from the time from
>>> signal manufacturers advertising both schemes so wasn't sure if one was more
>>> common than the other in practice, asking for a friend who's building a diorama
>>
>> From:
>>
>> <https://www.scienceabc.com/innovation/ready-steady-go-the-evolution-of-traffic-lights.html#the-first-four-way-and-three-colour-traffic-lights>
>>
>>
>> "The first electric traffic light had only red and green lights; it did not
>> have a yellow light like modern-day traffic signals. Instead of a yellow
>> light, it had a buzzer sound that was used to indicate that the signal would
>> be changing soon."
>
> Well the first is pretty long ago. As I understand it two-lights were still
> being used in some smaller municipalities well into the 60s, even 70s maybe.
>
>> Growing up, we had a variety of "traffic signals" -- including *single*
>> lights. Note that a light can also FLASH -- which conveys additional meaning.
>
> The intersection in the center of the town I grew up in had a hanging flashing
> red/amber lamp well into the 70s until it was replaced with full signals around
> the year I was born. Second-hand info, obviously.
>
>> E.g., here, our left-turn arrows flash yellow while oncoming traffic
>> has a solid green (we use a "lagging left" strategy). So, you can
>> legally enter the intersection (for a left turn) and execute that turn
>> *if* conditions permit.
>
> There are a few signals like this in MA but they're currently rare. More common
> in Rhode Island.
>
> Usually you're either fortunate enough to have a fully protected green arrow in
> a dedicated left turn lane that then sequences back to solid yellow arrow and
> red, or yield on green and fight the yellow trap at "less congested"
> intersections with a single lane of traffic.
>
> Sometimes the green arrow sequences to solid green at edge-case intersections.

The norm for intersections with left turn lanes (and associated "arrows")
is to get a left arrow AFTER the ongoing traffic has had it's "green" and
transitioned to "red". This is contrary to "leading left" which is popular
in the rest of the country -- traffic is stopped and left turn arrows appear.
They eventually return to red BEFORE the oncoming traffic is allowed to
proceed. (of course, this also applies to the traffic in the lanes to the
right of the left turn lane).

As a result, we have three different behaviors for left turning traffic
control:
- lagging left (the norm)
- leading left (usually explicitly posted as such)
- this hybrid flashing yellow to green (as well as green to flashing yellow)

> There's always some confusion as to whether one can turn on a red arrow; at
> least in MA a red arrow is no different than a solid red signal for your lane
> (just implies thee are multiple lights for your direction of travel that are
> timed differently) so you can turn on a red arrow any time you can turn on a
> solid red.

On Monday, May 31, 2021 at 3:34:37 PM UTC-7, Don Y wrote:
> On 5/31/2021 3:19 PM, Ed Lee wrote:
> > On Monday, May 31, 2021 at 3:08:19 PM UTC-7, bitrex wrote:
> >> On 5/31/2021 5:09 PM, Don Y wrote:
> >>> On 5/31/2021 1:24 PM, bitrex wrote:
> >>>> When two-light traffic signals were still somewhat common in the US
> >>>> (bit before my time..) does anyone know which arrangement was more
> >>>> common, for all signals to go dark in both directions as a
> >>>> replacement for the missing yellow, or for red and green to come on in
> >>>> the respective direction in lieu of a yellow in that direction.
> >>>>
> >>>> Or was it just municipality preference. I've seen ad copy from the
> >>>> time from signal manufacturers advertising both schemes so wasn't
> >>>> sure if one was more common than the other in practice, asking for a
> >>>> friend who's building a diorama
> >>>
> >>> From:
> >>>
> >>> <https://www.scienceabc.com/innovation/ready-steady-go-the-evolution-of-traffic-lights.html#the-first-four-way-and-three-colour-traffic-lights>
> >>>
> >>>
> >>>
> >>>
> "The first electric traffic light had only red and green lights; it did
> >>> not have a yellow light like modern-day traffic signals. Instead of a
> >>> yellow light, it had a buzzer sound that was used to indicate that the
> >>> signal would be changing soon."
> >> Well the first is pretty long ago. As I understand it two-lights were
> >> still being used in some smaller municipalities well into the 60s, even
> >> 70s maybe.
> >>> Growing up, we had a variety of "traffic signals" -- including *single*
> >>> lights. Note that a light can also FLASH -- which conveys additional
> >>> meaning.
> >> The intersection in the center of the town I grew up in had a hanging
> >> flashing red/amber lamp well into the 70s until it was replaced with full
> >> signals around the year I was born. Second-hand info, obviously.
> >>> E.g., here, our left-turn arrows flash yellow while oncoming traffic has
> >>> a solid green (we use a "lagging left" strategy). So, you can legally
> >>> enter the intersection (for a left turn) and execute that turn *if*
> >>> conditions permit.
> >> There are a few signals like this in MA but they're currently rare. More
> >> common in Rhode Island.
> >>
> >> Usually you're either fortunate enough to have a fully protected green
> >> arrow in a dedicated left turn lane that then sequences back to solid
> >> yellow arrow and red, or yield on green and fight the yellow trap at "less
> >> congested" intersections with a single lane of traffic.
> >>
> >> Sometimes the green arrow sequences to solid green at edge-case
> >> intersections.
> >>
> >> There's always some confusion as to whether one can turn on a red arrow;
> >> at least in MA a red arrow is no different than a solid red signal for
> >> your lane (just implies thee are multiple lights for your direction of
> >> travel that are timed differently) so you can turn on a red arrow any time
> >> you can turn on a solid red.
> >
> > And flashing red?
> >
> > Here, in San Mateo, at night, El Camino Real (main road in spanish) is
> > always flashing red. I assume it's merger beware. Ongoing traffic don't
> > even slow down.
> A flashing red light is interpreted as a stop sign; come to a complete
> stop, proceed when safe to do so.
>
> The pedestrian crossings that we have (NOT at intersections but, rather,
> between intersections) will signal solid red to stop all traffic while
> the pedestrians are given time to cross. This transitions to blinking red
> to alert drivers to check for laggers before proceeding. Then, the flashing
> disappears (there is no "green" light).

No transition to anything else, just constant flashing red. Other cars don't stop. I just follow them.

On 5/31/2021 3:14 PM, bitrex wrote:
> Hanging red/amber single-light flashers seem unpopular in my area now, probably
> due to maintenance cost. Most seem to have been replaced by something like a
> solar powered STOP sign with red LEDs for the side route, and the same but
> CAUTION for the main route.

It was common for a hanging flashing red (with flashing yellow on the
cross street) to be present at intersections that were either obscured
by flora or known to be "problematic" (folks ignoring the fact
that there *might* be cross traffic present). I guess the thinking
being that it is easier to KEEP a hanging light visible than it is to
HOPE folks will see stop signs that can easily be overgrown by
shrubbery.

It was also common to see a hanging flashing yellow (*two* sided)
on very narrow roads -- e.g., crossing single-lane bridges off
the beaten track. Again, I think the light was just used to stress
the point.

On 5/31/2021 3:43 PM, Ed Lee wrote:
> On Monday, May 31, 2021 at 3:34:37 PM UTC-7, Don Y wrote:
>> On 5/31/2021 3:19 PM, Ed Lee wrote:
>>> On Monday, May 31, 2021 at 3:08:19 PM UTC-7, bitrex wrote:
>>>> On 5/31/2021 5:09 PM, Don Y wrote:
>>>>> On 5/31/2021 1:24 PM, bitrex wrote:
>>>>>> When two-light traffic signals were still somewhat common in the US
>>>>>> (bit before my time..) does anyone know which arrangement was more
>>>>>> common, for all signals to go dark in both directions as a
>>>>>> replacement for the missing yellow, or for red and green to come on in
>>>>>> the respective direction in lieu of a yellow in that direction.
>>>>>>
>>>>>> Or was it just municipality preference. I've seen ad copy from the
>>>>>> time from signal manufacturers advertising both schemes so wasn't
>>>>>> sure if one was more common than the other in practice, asking for a
>>>>>> friend who's building a diorama
>>>>>
>>>>> From:
>>>>>
>>>>> <https://www.scienceabc.com/innovation/ready-steady-go-the-evolution-of-traffic-lights.html#the-first-four-way-and-three-colour-traffic-lights>
>>>>>
>>>>>
>>>>>
>>>>>
>> "The first electric traffic light had only red and green lights; it did
>>>>> not have a yellow light like modern-day traffic signals. Instead of a
>>>>> yellow light, it had a buzzer sound that was used to indicate that the
>>>>> signal would be changing soon."
>>>> Well the first is pretty long ago. As I understand it two-lights were
>>>> still being used in some smaller municipalities well into the 60s, even
>>>> 70s maybe.
>>>>> Growing up, we had a variety of "traffic signals" -- including *single*
>>>>> lights. Note that a light can also FLASH -- which conveys additional
>>>>> meaning.
>>>> The intersection in the center of the town I grew up in had a hanging
>>>> flashing red/amber lamp well into the 70s until it was replaced with full
>>>> signals around the year I was born. Second-hand info, obviously.
>>>>> E.g., here, our left-turn arrows flash yellow while oncoming traffic has
>>>>> a solid green (we use a "lagging left" strategy). So, you can legally
>>>>> enter the intersection (for a left turn) and execute that turn *if*
>>>>> conditions permit.
>>>> There are a few signals like this in MA but they're currently rare. More
>>>> common in Rhode Island.
>>>>
>>>> Usually you're either fortunate enough to have a fully protected green
>>>> arrow in a dedicated left turn lane that then sequences back to solid
>>>> yellow arrow and red, or yield on green and fight the yellow trap at "less
>>>> congested" intersections with a single lane of traffic.
>>>>
>>>> Sometimes the green arrow sequences to solid green at edge-case
>>>> intersections.
>>>>
>>>> There's always some confusion as to whether one can turn on a red arrow;
>>>> at least in MA a red arrow is no different than a solid red signal for
>>>> your lane (just implies thee are multiple lights for your direction of
>>>> travel that are timed differently) so you can turn on a red arrow any time
>>>> you can turn on a solid red.
>>>
>>> And flashing red?
>>>
>>> Here, in San Mateo, at night, El Camino Real (main road in spanish) is
>>> always flashing red. I assume it's merger beware. Ongoing traffic don't
>>> even slow down.
>> A flashing red light is interpreted as a stop sign; come to a complete
>> stop, proceed when safe to do so.
>>
>> The pedestrian crossings that we have (NOT at intersections but, rather,
>> between intersections) will signal solid red to stop all traffic while
>> the pedestrians are given time to cross. This transitions to blinking red
>> to alert drivers to check for laggers before proceeding. Then, the flashing
>> disappears (there is no "green" light).
>
> No transition to anything else, just constant flashing red. Other cars don't stop. I just follow them.

Correct. Flashing red just means "this is a stop sign". See my other
comments (including that above).

<https://besteride.com/what-does-a-flashing-red-light-mean/>

On 5/31/2021 6:45 PM, Don Y wrote:
> On 5/31/2021 3:43 PM, Ed Lee wrote:
>> On Monday, May 31, 2021 at 3:34:37 PM UTC-7, Don Y wrote:
>>> On 5/31/2021 3:19 PM, Ed Lee wrote:
>>>> On Monday, May 31, 2021 at 3:08:19 PM UTC-7, bitrex wrote:
>>>>> On 5/31/2021 5:09 PM, Don Y wrote:
>>>>>> On 5/31/2021 1:24 PM, bitrex wrote:
>>>>>>> When two-light traffic signals were still somewhat common in the US
>>>>>>> (bit before my time..) does anyone know which arrangement was more
>>>>>>> common, for all signals to go dark in both directions as a
>>>>>>> replacement for the missing yellow, or for red and green to come
>>>>>>> on in
>>>>>>> the respective direction in lieu of a yellow in that direction.
>>>>>>>
>>>>>>> Or was it just municipality preference. I've seen ad copy from the
>>>>>>> time from signal manufacturers advertising both schemes so wasn't
>>>>>>> sure if one was more common than the other in practice, asking for a
>>>>>>> friend who's building a diorama
>>>>>>
>>>>>> From:
>>>>>>
>>>>>> <https://www.scienceabc.com/innovation/ready-steady-go-the-evolution-of-traffic-lights.html#the-first-four-way-and-three-colour-traffic-lights>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>> "The first electric traffic light had only red and green lights; it did
>>>>>> not have a yellow light like modern-day traffic signals. Instead of a
>>>>>> yellow light, it had a buzzer sound that was used to indicate that
>>>>>> the
>>>>>> signal would be changing soon."
>>>>> Well the first is pretty long ago. As I understand it two-lights were
>>>>> still being used in some smaller municipalities well into the 60s,
>>>>> even
>>>>> 70s maybe.
>>>>>> Growing up, we had a variety of "traffic signals" -- including
>>>>>> *single*
>>>>>> lights. Note that a light can also FLASH -- which conveys additional
>>>>>> meaning.
>>>>> The intersection in the center of the town I grew up in had a hanging
>>>>> flashing red/amber lamp well into the 70s until it was replaced
>>>>> with full
>>>>> signals around the year I was born. Second-hand info, obviously.
>>>>>> E.g., here, our left-turn arrows flash yellow while oncoming
>>>>>> traffic has
>>>>>> a solid green (we use a "lagging left" strategy). So, you can legally
>>>>>> enter the intersection (for a left turn) and execute that turn *if*
>>>>>> conditions permit.
>>>>> There are a few signals like this in MA but they're currently rare.
>>>>> More
>>>>> common in Rhode Island.
>>>>>
>>>>> Usually you're either fortunate enough to have a fully protected green
>>>>> arrow in a dedicated left turn lane that then sequences back to solid
>>>>> yellow arrow and red, or yield on green and fight the yellow trap
>>>>> at "less
>>>>> congested" intersections with a single lane of traffic.
>>>>>
>>>>> Sometimes the green arrow sequences to solid green at edge-case
>>>>> intersections.
>>>>>
>>>>> There's always some confusion as to whether one can turn on a red
>>>>> arrow;
>>>>> at least in MA a red arrow is no different than a solid red signal for
>>>>> your lane (just implies thee are multiple lights for your direction of
>>>>> travel that are timed differently) so you can turn on a red arrow
>>>>> any time
>>>>> you can turn on a solid red.
>>>>
>>>> And flashing red?
>>>>
>>>> Here, in San Mateo, at night, El Camino Real (main road in spanish) is
>>>> always flashing red. I assume it's merger beware. Ongoing traffic don't
>>>> even slow down.
>>> A flashing red light is interpreted as a stop sign; come to a complete
>>> stop, proceed when safe to do so.
>>>
>>> The pedestrian crossings that we have (NOT at intersections but, rather,
>>> between intersections) will signal solid red to stop all traffic while
>>> the pedestrians are given time to cross. This transitions to blinking
>>> red
>>> to alert drivers to check for laggers before proceeding. Then, the
>>> flashing
>>> disappears (there is no "green" light).
>>
>> No transition to anything else, just constant flashing red.  Other
>> cars don't stop.  I just follow them.
>
> Correct.  Flashing red just means "this is a stop sign".  See my other
> comments (including that above).
>
> <https://besteride.com/what-does-a-flashing-red-light-mean/>
>

A flashing solid red = stop sign where I am too. Never seen a flashing
red arrow.

In MA it's legal to turn left on a red in a couple circumstances like
turning left from a one way street, onto a one way street. In RI a left
on red is always prohibited.

On 5/31/2021 5:14 PM, bitrex wrote:

> A flashing solid red = stop sign where I am too. Never seen a flashing red arrow.
>
> In MA it's legal to turn left on a red in a couple circumstances like turning
> left from a one way street, onto a one way street. In RI a left on red is
> always prohibited.

I recall, many years ago, a gummit initiative to get states to adopt right on
red (and left on red if from a one-way street onto another). I think to
cut emissions/fuel waste.

Each area of the country has different ways of tackling "traffic"
(and traffic PROBLEMS).

In Chicago, "rotaries" were rare (IIRC, there's one on Golf? out by
Mount Prospect that would rattle most folks seeing it for the first time).
Back east, they're pretty commonplace (e.g, Alewife Brook/Fresh Pond,
Revere Beach/VFW) and folks have no problem navigating them at highway
speeds. Here, I sometimes see little 'circles' in intersections but you
barely have to turn the steering wheel to avoid them!

Frontage roads are used in some places to pull traffic off of the main
feeders.

We've been adopting these crazy intersections where you go THROUGH the
intersection, make a left and then queue at the light that you just went
through, from the other direction, in order to make a turn.

There's also talk of "divided grade" intersections (I've encountered
them in a few other places) where through traffic passes UNDER the
cross traffic and only the traffic wanting to make a turn peels off.

Visitors from NYC are always amazed that traffic "in town", here, moves
at 45 MPH and lights are ~mile apart. OTOH, they wonder how pedestrians
manage to cross without jaywalking!

On Mon, 31 May 2021 18:08:14 -0400, bitrex <user@example.net> wrote:

>On 5/31/2021 5:09 PM, Don Y wrote:
>> On 5/31/2021 1:24 PM, bitrex wrote:
>>> When two-light traffic signals were still somewhat common in the US
>>> (bit before my time..) does anyone know which arrangement was more
>>> common, for all signals to go dark in both directions as a replacement
>>> for the missing yellow, or for red and green to come on in the
>>> respective direction in lieu of a yellow in that direction.
>>>
>>> Or was it just municipality preference. I've seen ad copy from the
>>> time from signal manufacturers advertising both schemes so wasn't sure
>>> if one was more common than the other in practice, asking for a friend
>>> who's building a diorama
>>
>> From:
>>
>> <https://www.scienceabc.com/innovation/ready-steady-go-the-evolution-of-traffic-lights.html#the-first-four-way-and-three-colour-traffic-lights>
>>
>>
>> "The first electric traffic light had only red and green lights; it did
>> not have a yellow light like modern-day traffic signals. Instead of a
>> yellow light, it had a buzzer sound that was used to indicate that the
>> signal would be changing soon."
>
>Well the first is pretty long ago. As I understand it two-lights were
>still being used in some smaller municipalities well into the 60s, even
>70s maybe.

I remember seeing two-light (red and green both went on rather than
having a yellow) in NYC ca. 1974.

>> Growing up, we had a variety of "traffic signals" -- including *single*
>> lights.  Note that a light can also FLASH -- which conveys additional
>> meaning.
>
>The intersection in the center of the town I grew up in had a hanging
>flashing red/amber lamp well into the 70s until it was replaced with
>full signals around the year I was born. Second-hand info, obviously.
>
>> E.g., here, our left-turn arrows flash yellow while oncoming traffic
>> has a solid green (we use a "lagging left" strategy).  So, you can
>> legally enter the intersection (for a left turn) and execute that turn
>> *if* conditions permit.
>
>There are a few signals like this in MA but they're currently rare. More
>common in Rhode Island.
>
>Usually you're either fortunate enough to have a fully protected green
>arrow in a dedicated left turn lane that then sequences back to solid
>yellow arrow and red, or yield on green and fight the yellow trap at
>"less congested" intersections with a single lane of traffic.
>
>Sometimes the green arrow sequences to solid green at edge-case
>intersections.
>
>There's always some confusion as to whether one can turn on a red arrow;
>at least in MA a red arrow is no different than a solid red signal for
>your lane (just implies thee are multiple lights for your direction of
>travel that are timed differently) so you can turn on a red arrow any
>time you can turn on a solid red.
--
Best regards,
Spehro Pefhany

On Tue, 01 Jun 2021 02:03:06 -0400, Spehro Pefhany
<speffSNIP@interlogDOTyou.knowwhat> wrote:

>On Mon, 31 May 2021 18:08:14 -0400, bitrex <user@example.net> wrote:
>
>>On 5/31/2021 5:09 PM, Don Y wrote:
>>> On 5/31/2021 1:24 PM, bitrex wrote:
>>>> When two-light traffic signals were still somewhat common in the US
>>>> (bit before my time..) does anyone know which arrangement was more
>>>> common, for all signals to go dark in both directions as a replacement
>>>> for the missing yellow, or for red and green to come on in the
>>>> respective direction in lieu of a yellow in that direction.
>>>>
>>>> Or was it just municipality preference. I've seen ad copy from the
>>>> time from signal manufacturers advertising both schemes so wasn't sure
>>>> if one was more common than the other in practice, asking for a friend
>>>> who's building a diorama
>>>
>>> From:
>>>
>>> <https://www.scienceabc.com/innovation/ready-steady-go-the-evolution-of-traffic-lights.html#the-first-four-way-and-three-colour-traffic-lights>
>>>
>>>
>>> "The first electric traffic light had only red and green lights; it did
>>> not have a yellow light like modern-day traffic signals. Instead of a
>>> yellow light, it had a buzzer sound that was used to indicate that the
>>> signal would be changing soon."
>>
>>Well the first is pretty long ago. As I understand it two-lights were
>>still being used in some smaller municipalities well into the 60s, even
>>70s maybe.
>
>I remember seeing two-light (red and green both went on rather than
>having a yellow) in NYC ca. 1974.

I saw some like that, maybe late 60's, in some small town, maybe in
Alabama. I think the whole thing had two light bulbs. Red was on top
in one direction, bottom in the other.

--

John Larkin Highland Technology, Inc

The best designs are necessarily accidental.

On Monday, May 31, 2021 at 4:24:27 PM UTC-4, bitrex wrote:
> When two-light traffic signals were still somewhat common in the US (bit
> before my time..) does anyone know which arrangement was more common,
> for all signals to go dark in both directions as a replacement for the
> missing yellow, or for red and green to come on in the respective
> direction in lieu of a yellow in that direction.
>
> Or was it just municipality preference. I've seen ad copy from the time
> from signal manufacturers advertising both schemes so wasn't sure if one
> was more common than the other in practice, asking for a friend who's
> building a diorama

That's okay for the early piss-ant roads where the speed limit was 15 MPH. NHTSA and its regulation changed all that- probably respecting information on 100,000 intersection crash fatalities. These days a yellow is required and its duration is supposed to be 1 second per 10 MPH of the road speed limit, which I find rarely observed. Yellow is almost always too short.

bitrex wrote:
> When two-light traffic signals were still somewhat common in the US
> (bit before my time..) does anyone know which arrangement was more
> common, for all signals to go dark in both directions as a
> replacement for the missing yellow, or for red and green to come on
> in the respective direction in lieu of a yellow in that direction.
>
> Or was it just municipality preference. I've seen ad copy from the
> time from signal manufacturers advertising both schemes so wasn't
> sure if one was more common than the other in practice, asking for a
> friend who's building a diorama

In NYC they were both on in the rare instance that was in place.

In the other possibility, I think you mean both go dark in one direction
while the other direction is red.

--
Defund the Thought Police

On 6/2/2021 5:43 AM, Tom Del Rosso wrote:
> bitrex wrote:
>> When two-light traffic signals were still somewhat common in the US
>> (bit before my time..) does anyone know which arrangement was more
>> common, for all signals to go dark in both directions as a
>> replacement for the missing yellow, or for red and green to come on
>> in the respective direction in lieu of a yellow in that direction.
>>
>> Or was it just municipality preference. I've seen ad copy from the
>> time from signal manufacturers advertising both schemes so wasn't
>> sure if one was more common than the other in practice, asking for a
>> friend who's building a diorama
>
> In NYC they were both on in the rare instance that was in place.
>
> In the other possibility, I think you mean both go dark in one direction
> while the other direction is red.
>
>

Here's an ad for a two light, it says "when the red STOP goes out there
is an interval of about 3 seconds before the green GO lights up, and
vice versa."

<http://www.kbrhorse.net/sigpics2/darley01.jpg>

That sounds to me like the whole signal goes dark for 3 seconds, but
maybe I'm misunderstanding the phasing.

On 6/2/2021 12:28 PM, bitrex wrote:
> On 6/2/2021 5:43 AM, Tom Del Rosso wrote:
>> bitrex wrote:
>>> When two-light traffic signals were still somewhat common in the US
>>> (bit before my time..) does anyone know which arrangement was more
>>> common, for all signals to go dark in both directions as a
>>> replacement for the missing yellow, or for red and green to come on
>>> in the respective direction in lieu of a yellow in that direction.
>>>
>>> Or was it just municipality preference. I've seen ad copy from the
>>> time from signal manufacturers advertising both schemes so wasn't
>>> sure if one was more common than the other in practice, asking for a
>>> friend who's building a diorama
>>
>> In NYC they were both on in the rare instance that was in place.
>>
>> In the other possibility, I think you mean both go dark in one direction
>> while the other direction is red.
>>
>>
>
> Here's an ad for a two light, it says "when the red STOP goes out there
> is an interval of about 3 seconds before the green GO lights up, and
> vice versa."
>
> <http://www.kbrhorse.net/sigpics2/darley01.jpg>
>
> That sounds to me like the whole signal goes dark for 3 seconds, but
> maybe I'm misunderstanding the phasing.

Ah, here's an example of it operating:

<https://youtu.be/ohi-ijEWUR0>