This is something I've sort of wondered, around here in the GTA (and possibly all of Ontario), our traffic lights operate 24 hours a day, but I know of places that switch their traffic lights to yellow flash or red flash in the middle of the night.
The question I'm wondering is ambiguity, if we cannot see the cross traffic lights (which happens in many places which use four sided signals) how do we know what the right of way situation is after hours. If you don't follow what I mean, a flashing red of course tells the driver to stop, but on its own, it doesn't acknowledge who has right of way in the intersection.
Is there a specific law that when lights switch to red flash or yellow flash, that one side always has to have a yellow flash, or are there situations in the middle of the night where an intersection has all 4 directions face a red flash?
I wonder how many problems this causes, I mean do a quick Google search on the meaning of a flashing red on the internet, and there will be many sources that will say that a flashing red, in a single beacon flashing, or in a traffic light, means the same thing as a four way stop, this is definitely not always the case.
I was wondering the exact same thing earlier today, as I was thinking about an intersection in Nampa that is currently a 4 way stop, that there is talks about maybe making a signal. My argument against that is that for a lot of the day, it functions great as a 4 way stop. There aren't usually more than a few cars there at a time. But there's a few hours each day where a signal would be beneficial. I was pondering the possibility of it being a standard signal during peak hours, and a 4 way flashing stop at other times. Signals don't do that around here, but it was interesting for me to think about.
In Appleton, WI all of the traffic signals along College Ave have flashing reds in the Downtown area. The street is popular for teens to cruise, and there are a lot of pedestrians. I think the reason why there aren't many all way flashing reds at night is because traffic engineers probably find it more beneficial to keep a signal operational if traffic is pretty equal coming from all parts of an intersection. With the flashing yellow, the logic is that traffic shouldn't have to stop for few cars on side roads, and traffic has calmed down so a lone car can turn safely after stopping.
You're lucky you have traffic lights that go into flash mode at all... here in Australia all lights must operate 24/7 no matter what :banghead:. They are trialling a configuration where after around 10PM the intersection defaults to solid red on all approaches, only turning green after a car has arrived and come to a complete stop, the idea being to reduce travel speed and so enhance safety.
I guess if you can't see the other signal it's safest to assume the cross traffic isn't going to stop, which probably isn't such a bad idea in any case given you're more likely to be dealing with drunk or tired drivers during the small hours.
Quote from: peterj920 on May 30, 2016, 01:58:12 AM
In Appleton, WI all of the traffic signals along College Ave have flashing reds in the Downtown area. The street is popular for teens to cruise, and there are a lot of pedestrians. I think the reason why there aren't many all way flashing reds at night is because traffic engineers probably find it more beneficial to keep a signal operational if traffic is pretty equal coming from all parts of an intersection. With the flashing yellow, the logic is that traffic shouldn't have to stop for few cars on side roads, and traffic has calmed down so a lone car can turn safely after stopping.
I agree. That is my experience as well. The only times I can recall that a signal is
set to go to flashing mode is a flashing mode to red/yellow for the reason you describe above. Prevent main street from having to stop at all and to give it absolute priority. When two equivalent streets meet, there is usually enough traffic to justify a signal 24/7.
However, I have seen many signals malfunction. Sometimes after a power outage a signal goes to flash mode before repairs can be made to get the signal fully functioning. I recall seeing this in LA where there are very few signals that regularly go into flash, but every signal has a flash mode for malfunctions. Where two main streets meet - all red flash.
Here in suburban MD, most signals do flash from 1 am to 5:30 am. I don't recall any signal flashing all-red.
Quote from: MisterSG1 on May 29, 2016, 10:36:51 PM
This is something I've sort of wondered, around here in the GTA (and possibly all of Ontario), our traffic lights operate 24 hours a day, but I know of places that switch their traffic lights to yellow flash or red flash in the middle of the night.
The convention for Ontario is to run 24/7 and to go into all red flash if there is a fault.
Quote from: MisterSG1 on May 29, 2016, 10:36:51 PM
The question I'm wondering is ambiguity, if we cannot see the cross traffic lights (which happens in many places which use four sided signals) how do we know what the right of way situation is after hours. If you don't follow what I mean, a flashing red of course tells the driver to stop, but on its own, it doesn't acknowledge who has right of way in the intersection.
Is there a specific law that when lights switch to red flash or yellow flash, that one side always has to have a yellow flash, or are there situations in the middle of the night where an intersection has all 4 directions face a red flash?
I wonder how many problems this causes, I mean do a quick Google search on the meaning of a flashing red on the internet, and there will be many sources that will say that a flashing red, in a single beacon flashing, or in a traffic light, means the same thing as a four way stop, this is definitely not always the case.
Which is why the convention here is what it is. Driver expectancy around here is that a flashing red is an all way stop, so flashing amber is definitely frowned upon.
Not to say it doesn't happen in some municipalities, but it is definitely not a good idea.
But as inferred in the OP, standard practice is to cycle 24 hours a day. Considering that a properly designed actuated signal should cycle to the side street almost instantly, that small delay is considered to be worth the clarity.
We used to have some lights in Fairfax City that went to a flashing cycle at night. They all served shopping centers. The thru street got flashing yellow and the shopping centers got flashing red. I thought that was pretty reasonable since there might have been at most maybe one business open 24 hours (a 7-11) in those shopping centers. They were gone at least by 2001 in favor of 24/7 signals.
I've noticed a few times at intersections where signals should be running 24/7, but are in flash mode due to a power outage or other issue: People have seemed to forget that the flashing yellow has the right of way. I've seen where people will stop and treat it as a 4-way stop. That's nice...but that's not the way it is supposed to be done!
I've thought of this every so often. Some towns switch to red/yellow, others red/red, still others offer a mixed bag. If you can't see the cross-traffic signals, then there's no foolproof way knowing. As much as I dislike stoplights, I'd rather signals operate 24/7 than not know whether I can safely go or not.
Until about 15 years ago, all of the stoplights on US-17 (now US-17 Business) from River Bend all the way to downtown New Bern (except for the intersection at Broad St and Queen St) flashed yellow for mainline traffic and red for cross traffic from midnight until 6am. Now only a couple do, mostly in downtown New Bern. All of the rest are 24/7 stoplights.
I'm with kphoger, both on the dislike of, and feeling the need for normal operation 24/7.
Interestingly enough, however, we have more wrecks now from people a)slamming on brakes because the light went yellow and b) from people speeding up trying to beat the light than we ever did because of cross traffic running their flashing red at o-dark 30 #gofigure.
Quote from: slorydn1 on May 30, 2016, 11:38:25 PM
Until about 15 years ago, all of the stoplights on US-17 (now US-17 Business) from River Bend all the way to downtown New Bern (except for the intersection at Broad St and Queen St) flashed yellow for mainline traffic and red for cross traffic from midnight until 6am. Now only a couple do, mostly in downtown New Bern. All of the rest are 24/7 stoplights.
I'm with kphoger, both on the dislike of, and feeling the need for normal operation 24/7.
Interestingly enough, however, we have more wrecks now from people a)slamming on brakes because the light went yellow and b) from people speeding up trying to beat the light than we ever did because of cross traffic running their flashing red at o-dark 30 #gofigure.
What you describe is not surprising. People are used to driving down US 17 without stopping. When the signals flashed, that would be the case - even with cross traffic present. Side traffic would simply have to yield. But now, people drive fast through green lights and don't expect any of them to turn yellow. The disruption leads to more accidents.
While brainstorming after reading a few posts, I think I know a solution that could possibly work to eliminate the ambiguity, unfortunately it would require a slight tweak of the rules.
Flashing Yellow - Proceed with caution (no change in meaning)
Flashing Red - Stop, this intersection is a FOUR WAY or ALL WAY stop
Flashing Red + Yellow - Stop, and proceed only if safe to do so, cross traffic has right of way
Of course for this to work, every solo red beacon out there across both Rural America and Canada would have to be tweaked to this new format, so it would be expensive, the phasing of the new definition would have to be implemented everywhere on the same date as to eliminate the ambiguity entirely (where some have the old definition of flashing red and some have the new definition of flashing red). Personally I see this as a possible solution to this issue and can keep overall traffic flow in better shape.
Quote from: MisterSG1 on May 31, 2016, 07:52:02 AM
While brainstorming after reading a few posts, I think I know a solution that could possibly work to eliminate the ambiguity, unfortunately it would require a slight tweak of the rules.
Flashing Yellow - Proceed with caution (no change in meaning)
Flashing Red - Stop, this intersection is a FOUR WAY or ALL WAY stop
Flashing Red + Yellow - Stop, and proceed only if safe to do so, cross traffic has right of way
Of course for this to work, every solo red beacon out there across both Rural America and Canada would have to be tweaked to this new format, so it would be expensive, the phasing of the new definition would have to be implemented everywhere on the same date as to eliminate the ambiguity entirely (where some have the old definition of flashing red and some have the new definition of flashing red). Personally I see this as a possible solution to this issue and can keep overall traffic flow in better shape.
And a tweak to all of the existing signal controllers too. So, you're talking billions of dollars and countless working hours. And the transition period will undoubtedly create more collisions, and ensuing lawsuits, tying up even more resources and dollars.
All to do what? Save a handful of people a few seconds in the middle of the night? :crazy:
Quote from: MisterSG1 on May 31, 2016, 07:52:02 AM
Every solo red beacon out there across both Rural America and Canada would have to be tweaked to this new format, so it would be expensive, the phasing of the new definition would have to be implemented everywhere on the same date as to eliminate the ambiguity entirely (where some have the old definition of flashing red and some have the new definition of flashing red).
Quote from: cbeach40 on May 31, 2016, 09:29:12 AM
And a tweak to all of the existing signal controllers too. So, you're talking billions of dollars and countless working hours. And the transition period will undoubtedly create more collisions, and ensuing lawsuits, tying up even more resources and dollars.
All to do what? Save a handful of people a few seconds in the middle of the night? :crazy:
Well, sure, when you say it like
that... But, come on now, be realistic, those few seconds are pretty annoying!
Quote from: kphoger on May 31, 2016, 01:10:17 PM
Well, sure, when you say it like that... But, come on now, be realistic, those few seconds are pretty annoying!
That's what a right turn followed by a U-turn are for! ;)
Quote from: cbeach40 on May 31, 2016, 01:41:39 PM
Quote from: kphoger on May 31, 2016, 01:10:17 PM
Well, sure, when you say it like that... But, come on now, be realistic, those few seconds are pretty annoying!
That's what a right turn followed by a U-turn are for! ;)
Except that, in at least some places, U-turns are not allowed intersections with no traffic control devices. Which means you could get stuck at the exact same situation the next light down.
Quote from: kphoger on May 31, 2016, 01:45:22 PM
Quote from: cbeach40 on May 31, 2016, 01:41:39 PM
Quote from: kphoger on May 31, 2016, 01:10:17 PM
Well, sure, when you say it like that... But, come on now, be realistic, those few seconds are pretty annoying!
That's what a right turn followed by a U-turn are for! ;)
Except that, in at least some places, U-turns are not allowed intersections with no traffic control devices. Which means you could get stuck at the exact same situation the next light down.
My bad, I was meaning mid-block.
Quote from: cbeach40 on May 31, 2016, 01:49:49 PM
Quote from: kphoger on May 31, 2016, 01:45:22 PM
Quote from: cbeach40 on May 31, 2016, 01:41:39 PM
Quote from: kphoger on May 31, 2016, 01:10:17 PM
Well, sure, when you say it like that... But, come on now, be realistic, those few seconds are pretty annoying!
That's what a right turn followed by a U-turn are for! ;)
Except that, in at least some places, U-turns are not allowed intersections with no traffic control devices. Which means you could get stuck at the exact same situation the next light down.
My bad, I was meaning mid-block.
Right, mid-block U-turns are the kind of thing that will get you a ticket around here.
Why would someone thing flashing red meant "all-way stop" instead of simply "stop"? Around here, they're almost always on rural roads, often with the other road having flashing yellow.
Quote from: vdeane on May 31, 2016, 08:58:55 PM
Why would someone thing flashing red meant "all-way stop" instead of simply "stop"?
Driver expectancy. Per:
Quote from: vdeane on May 31, 2016, 08:58:55 PM
Around here, they're almost always on rural roads, often with the other road having flashing yellow.
Whereas urban intersections will have an all-read flash sequence, converting it to an AWS in emergency. Therefore the situation is being applied inconsistently. And inconsistency is the worst situation possible when it comes to human factors in traffic engineering.
Quote from: kphoger on May 31, 2016, 01:52:47 PM
Right, mid-block U-turns are the kind of thing that will get you a ticket around here.
Well, changing one piece of ill-conceived legislation is far easier than changing signals across the board. :)
Quote from: cbeach40 on June 01, 2016, 09:47:48 AM
Quote from: vdeane on May 31, 2016, 08:58:55 PM
Why would someone thing flashing red meant "all-way stop" instead of simply "stop"?
Driver expectancy. Per:
Quote from: vdeane on May 31, 2016, 08:58:55 PM
Around here, they're almost always on rural roads, often with the other road having flashing yellow.
Whereas urban intersections will have an all-read flash sequence, converting it to an AWS in emergency. Therefore the situation is being applied inconsistently. And inconsistency is the worst situation possible when it comes to human factors in traffic engineering.
Quote from: kphoger on May 31, 2016, 01:52:47 PM
Right, mid-block U-turns are the kind of thing that will get you a ticket around here.
Well, changing one piece of ill-conceived legislation is far easier than changing signals across the board. :)
Around here urban intersections still have one direction flashing yellow and one red. Seems like the easier solution would be to switch all intersections to have one direction to flashing yellow, as flashing red in all directions will cause delays, waste gas, and is all around less efficient.
Quote from: UCFKnights on June 03, 2016, 10:07:23 AM
Quote from: cbeach40 on June 01, 2016, 09:47:48 AM
Quote from: vdeane on May 31, 2016, 08:58:55 PM
Why would someone thing flashing red meant "all-way stop" instead of simply "stop"?
Driver expectancy. Per:
Quote from: vdeane on May 31, 2016, 08:58:55 PM
Around here, they're almost always on rural roads, often with the other road having flashing yellow.
Whereas urban intersections will have an all-read flash sequence, converting it to an AWS in emergency. Therefore the situation is being applied inconsistently. And inconsistency is the worst situation possible when it comes to human factors in traffic engineering.
Quote from: kphoger on May 31, 2016, 01:52:47 PM
Right, mid-block U-turns are the kind of thing that will get you a ticket around here.
Well, changing one piece of ill-conceived legislation is far easier than changing signals across the board. :)
Around here urban intersections still have one direction flashing yellow and one red. Seems like the easier solution would be to switch all intersections to have one direction to flashing yellow, as flashing red in all directions will cause delays, waste gas, and is all around less efficient.
I understand what you are getting at, one direction, suppose N/S is the "major street" and suppose E/W is the "minor street", this sounds good in theory, but what about when you get to situations where you have two streets that are equally "major". Think about when the two main perpendicular streets in such a town meet, who gets the flashing yellow and who gets the flashing red. Hence this is why some intersections in places that switch to flashing yellow/flashing red mode have intersections with all flashing reds.
Generally, in the GTA, the light on the major street will remain green indefinitely as long as no one waits for the light on the minor street. This does suck when you are on the minor street and have to wait for the light to cycle entirely through, unlike what cbeach40 says, you have to wait usually at least 30 seconds for the light to change, as the ped signals will have to display 15-30 hand flashes before the street turns yellow (depending on how big the intersection is).
Quote from: vdeane on May 31, 2016, 08:58:55 PM
Why would someone thing flashing red meant "all-way stop" instead of simply "stop"? Around here, they're almost always on rural roads, often with the other road having flashing yellow.
There are a fair amount of the solo flashing beacons even in downtown Toronto, and there are ones where my brain wants to think that it means it's an all way stop, but it is not.....nearly made a mistake because of this. The flashing beacon on Richmond St (a one way that heads west, or in this case traffic moves to the right) is yellow, while the flashing beacon on Simcoe is red.
https://www.google.ca/maps/@43.6501412,-79.3872045,3a,15.7y,164.24h,87.3t/data=!3m6!1e1!3m4!1s3kY1dOPxT3PHwFmo14fUNQ!2e0!7i13312!8i6656?hl=en (https://www.google.ca/maps/@43.6501412,-79.3872045,3a,15.7y,164.24h,87.3t/data=!3m6!1e1!3m4!1s3kY1dOPxT3PHwFmo14fUNQ!2e0!7i13312!8i6656?hl=en)
A street I used to travel a lot when I went to go to Bolton, Healey Road, has a situation where you face two red flash beacons:
https://www.google.ca/maps/@43.8195639,-79.7751852,3a,62.3y,45.22h,90.16t/data=!3m6!1e1!3m4!1sMcVk0v9NMOAfZBQmFaaz2g!2e0!7i13312!8i6656?hl=en (https://www.google.ca/maps/@43.8195639,-79.7751852,3a,62.3y,45.22h,90.16t/data=!3m6!1e1!3m4!1sMcVk0v9NMOAfZBQmFaaz2g!2e0!7i13312!8i6656?hl=en)
This one at the intersection with Innis Lake Road (the northern continuation of Goreway Drive in Brampton) is an all way stop, so all four sides face the red flash.....but just 2 more intersections down you see this:
https://www.google.ca/maps/@43.8394778,-79.7552649,3a,15y,40.21h,89.37t/data=!3m6!1e1!3m4!1sbPwN73SPArlvF61vtxBMxg!2e0!7i13312!8i6656?hl=en (https://www.google.ca/maps/@43.8394778,-79.7552649,3a,15y,40.21h,89.37t/data=!3m6!1e1!3m4!1sbPwN73SPArlvF61vtxBMxg!2e0!7i13312!8i6656?hl=en)
This intersection with The Gore Road is just a stop sign, with a red flash....thus the beacon on The Gore Road is a yellow flash, it's my humble opinion that the flashing lights seem to stand out more than the stop signs, and my brain processes them before the stop signs. Despite the flashing red on its own not showing who has right of way.
Quote from: MisterSG1 on June 03, 2016, 10:06:17 PM
I understand what you are getting at, one direction, suppose N/S is the "major street" and suppose E/W is the "minor street", this sounds good in theory, but what about when you get to situations where you have two streets that are equally "major". Think about when the two main perpendicular streets in such a town meet, who gets the flashing yellow and who gets the flashing red. Hence this is why some intersections in places that switch to flashing yellow/flashing red mode have intersections with all flashing reds.
Generally, in the GTA, the light on the major street will remain green indefinitely as long as no one waits for the light on the minor street. This does suck when you are on the minor street and have to wait for the light to cycle entirely through, unlike what cbeach40 says, you have to wait usually at least 30 seconds for the light to change, as the ped signals will have to display 15-30 hand flashes before the street turns yellow (depending on how big the intersection is).
To the first question, I would pick whichever "main" street happens to carry the most through traffic or the one that is a main, signed highway. In this kind of situation though, perhaps not converting to flash mode is better (depending on traffic levels and location).
To the second statement: If an intersection has ped buttons on all sides and detection on all approaches, the signal could run in "free" mode with default green to the main street. In the free mode, the signal is not dependent upon the typical cycle length as it's operating on demand (basically, first come first served). The ped signals wouldn't rest in walk but could change to walk immediately on activation (allow walk to start mid-green), and side street can also be served immdiately when cars/peds arrive (both assuming no conflicting movements detected). I don't know how often signals are operated in such a manner, but I believe most modern controllers have the necessary settings to make this work.
Quote from: MisterSG1 on June 03, 2016, 10:06:17 PM
Quote from: UCFKnights on June 03, 2016, 10:07:23 AM
Quote from: cbeach40 on June 01, 2016, 09:47:48 AM
Quote from: vdeane on May 31, 2016, 08:58:55 PM
Why would someone thing flashing red meant "all-way stop" instead of simply "stop"?
Driver expectancy. Per:
Quote from: vdeane on May 31, 2016, 08:58:55 PM
Around here, they're almost always on rural roads, often with the other road having flashing yellow.
Whereas urban intersections will have an all-read flash sequence, converting it to an AWS in emergency. Therefore the situation is being applied inconsistently. And inconsistency is the worst situation possible when it comes to human factors in traffic engineering.
Quote from: kphoger on May 31, 2016, 01:52:47 PM
Right, mid-block U-turns are the kind of thing that will get you a ticket around here.
Well, changing one piece of ill-conceived legislation is far easier than changing signals across the board. :)
Around here urban intersections still have one direction flashing yellow and one red. Seems like the easier solution would be to switch all intersections to have one direction to flashing yellow, as flashing red in all directions will cause delays, waste gas, and is all around less efficient.
I understand what you are getting at, one direction, suppose N/S is the "major street" and suppose E/W is the "minor street", this sounds good in theory, but what about when you get to situations where you have two streets that are equally "major". Think about when the two main perpendicular streets in such a town meet, who gets the flashing yellow and who gets the flashing red. Hence this is why some intersections in places that switch to flashing yellow/flashing red mode have intersections with all flashing reds.
If traffic counts are equal, choose one direction at random. Its still better for traffic then the 4 way stop and eliminates the confusion.
Quote from: MisterSG1 on June 03, 2016, 10:06:17 PM
Generally, in the GTA, the light on the major street will remain green indefinitely as long as no one waits for the light on the minor street. This does suck when you are on the minor street and have to wait for the light to cycle entirely through, unlike what cbeach40 says, you have to wait usually at least 30 seconds for the light to change, as the ped signals will have to display 15-30 hand flashes before the street turns yellow (depending on how big the intersection is).
So... 20-30 seconds (based on those hand flashes)? Cool.
And again, I did qualify that by saying properly actuated. Resting in walk is not doing it right.
[EDIT] - Thinking further on the numbers provided, if it takes 30 seconds to get a green, then that would mean that the *side road* is a good 25-36 m wide. Or to put it another way, 8-10 lanes wide.
Yeah, if that's the kind of cross section you're dealing with, then putting it under red flash is an astoundingly bad idea.
Quote from: UCFKnights on June 04, 2016, 09:45:54 AM
If traffic counts are equal, choose one direction at random. Its still better for traffic then the 4 way stop and eliminates the confusion.
If counts are equal, then properly actuated cycling won't be a significant problem in terms of delay. And making a call like that "at random" ? Ummmmmmmm :confused:
Quote from: UCFKnights on June 04, 2016, 09:45:54 AM
Quote from: MisterSG1 on June 03, 2016, 10:06:17 PM
I understand what you are getting at, one direction, suppose N/S is the "major street" and suppose E/W is the "minor street", this sounds good in theory, but what about when you get to situations where you have two streets that are equally "major". Think about when the two main perpendicular streets in such a town meet, who gets the flashing yellow and who gets the flashing red. Hence this is why some intersections in places that switch to flashing yellow/flashing red mode have intersections with all flashing reds.
If traffic counts are equal, choose one direction at random. Its still better for traffic then the 4 way stop and eliminates the confusion.
Agreed. Unless you have long-range detection loops, which isn't likely because that means agencies would have to spend extra money. If it's an intersection where every leg is a low-volume urban street, however, I can see reason for a 4-way stop there, too.
I just got back from Omaha. Driving around late at night revealed that many signals switch to flashing yellow/red operation after hours. This was new to me, as all signals in Illinois require 24-hour operation, if I'm not mistaken.
Quote from: paulthemapguy on June 07, 2016, 12:01:13 PM
all signals in Illinois require 24-hour operation, if I'm not mistaken.
I've lived in more than one town in Illinois that switches at least some stoplights to flash mode late at night. Specifically Wheaton (2000—2006) and Herrin (2006-2008).
Quote from: kphoger on June 07, 2016, 04:01:24 PM
Quote from: paulthemapguy on June 07, 2016, 12:01:13 PM
all signals in Illinois require 24-hour operation, if I'm not mistaken.
I've lived in more than one town in Illinois that switches at least some stoplights to flash mode late at night. Specifically Wheaton (2000—2006) and Herrin (2006-2008).
This was a while back, but IDOT had a policy of it the signals went into flash mode, all sides would see a flashing red. Not sure if this is still the case.
Quote from: Big John on June 07, 2016, 04:08:01 PM
Quote from: kphoger on June 07, 2016, 04:01:24 PM
Quote from: paulthemapguy on June 07, 2016, 12:01:13 PM
all signals in Illinois require 24-hour operation, if I'm not mistaken.
I've lived in more than one town in Illinois that switches at least some stoplights to flash mode late at night. Specifically Wheaton (2000—2006) and Herrin (2006-2008).
This was a while back, but IDOT had a policy of it the signals went into flash mode, all sides would see a flashing red. Not sure if this is still the case.
The ones I remember were all red/red.
Quote from: UCFKnights on June 04, 2016, 09:45:54 AM
Quote from: MisterSG1 on June 03, 2016, 10:06:17 PM
Quote from: UCFKnights on June 03, 2016, 10:07:23 AM
Quote from: cbeach40 on June 01, 2016, 09:47:48 AM
Quote from: vdeane on May 31, 2016, 08:58:55 PM
Why would someone thing flashing red meant "all-way stop" instead of simply "stop"?
Driver expectancy. Per:
Quote from: vdeane on May 31, 2016, 08:58:55 PM
Around here, they're almost always on rural roads, often with the other road having flashing yellow.
Whereas urban intersections will have an all-read flash sequence, converting it to an AWS in emergency. Therefore the situation is being applied inconsistently. And inconsistency is the worst situation possible when it comes to human factors in traffic engineering.
Quote from: kphoger on May 31, 2016, 01:52:47 PM
Right, mid-block U-turns are the kind of thing that will get you a ticket around here.
Well, changing one piece of ill-conceived legislation is far easier than changing signals across the board. :)
Around here urban intersections still have one direction flashing yellow and one red. Seems like the easier solution would be to switch all intersections to have one direction to flashing yellow, as flashing red in all directions will cause delays, waste gas, and is all around less efficient.
I understand what you are getting at, one direction, suppose N/S is the "major street" and suppose E/W is the "minor street", this sounds good in theory, but what about when you get to situations where you have two streets that are equally "major". Think about when the two main perpendicular streets in such a town meet, who gets the flashing yellow and who gets the flashing red. Hence this is why some intersections in places that switch to flashing yellow/flashing red mode have intersections with all flashing reds.
If traffic counts are equal, choose one direction at random. Its still better for traffic then the 4 way stop and eliminates the confusion.
No, no, no.
Imagine if there was an accident at the intersection. They review the intersection and determine why one direction was flashing yellow and the other red. I don't think "Oh, we flipped a coin. Best out of 5 won." is going to fly in any engineering school or court.
Besides, the chances of the intersections having an equal amount of traffic late at night is quite low. In that case, you probably want the light running normal operation 24/7.
Quote from: jeffandnicole on June 07, 2016, 09:29:13 PM
Quote from: UCFKnights on June 04, 2016, 09:45:54 AM
Quote from: MisterSG1 on June 03, 2016, 10:06:17 PM
Quote from: UCFKnights on June 03, 2016, 10:07:23 AM
Quote from: cbeach40 on June 01, 2016, 09:47:48 AM
Quote from: vdeane on May 31, 2016, 08:58:55 PM
Why would someone thing flashing red meant "all-way stop" instead of simply "stop"?
Driver expectancy. Per:
Quote from: vdeane on May 31, 2016, 08:58:55 PM
Around here, they're almost always on rural roads, often with the other road having flashing yellow.
Whereas urban intersections will have an all-read flash sequence, converting it to an AWS in emergency. Therefore the situation is being applied inconsistently. And inconsistency is the worst situation possible when it comes to human factors in traffic engineering.
Quote from: kphoger on May 31, 2016, 01:52:47 PM
Right, mid-block U-turns are the kind of thing that will get you a ticket around here.
Well, changing one piece of ill-conceived legislation is far easier than changing signals across the board. :)
Around here urban intersections still have one direction flashing yellow and one red. Seems like the easier solution would be to switch all intersections to have one direction to flashing yellow, as flashing red in all directions will cause delays, waste gas, and is all around less efficient.
I understand what you are getting at, one direction, suppose N/S is the "major street" and suppose E/W is the "minor street", this sounds good in theory, but what about when you get to situations where you have two streets that are equally "major". Think about when the two main perpendicular streets in such a town meet, who gets the flashing yellow and who gets the flashing red. Hence this is why some intersections in places that switch to flashing yellow/flashing red mode have intersections with all flashing reds.
If traffic counts are equal, choose one direction at random. Its still better for traffic then the 4 way stop and eliminates the confusion.
No, no, no.
Imagine if there was an accident at the intersection. They review the intersection and determine why one direction was flashing yellow and the other red. I don't think "Oh, we flipped a coin. Best out of 5 won." is going to fly in any engineering school or court.
Besides, the chances of the intersections having an equal amount of traffic late at night is quite low. In that case, you probably want the light running normal operation 24/7.
Why would that matter? If there's a accident, why would they be investigating why one direction has a flasing yellow unless that somehow caused a problem? Either direction having a flashing yellow is perfectly valid from an engineering standpoint, and these random decisions are done all the time. Although I do agree that it is extremely unlikely the traffic counts are actually equal, some direction will be more popular.
Quote from: UCFKnights on June 08, 2016, 06:36:02 PM
Why would that matter? If there's a accident, why would they be investigating why one direction has a flasing yellow unless that somehow caused a problem?
To ensure that all responsible parties did everything they could reasonably do to prevent the accident. Making a random choice is not doing that.
Quote from: UCFKnights on June 08, 2016, 06:36:02 PM
Either direction having a flashing yellow is perfectly valid from an engineering standpoint,
If they both are equally valid for a yellow, then neither is valid for a flashing red.
Quote from: UCFKnights on June 08, 2016, 06:36:02 PM
and these random decisions are done all the time.
Not too often by engineers who want to keep being engineers. ;)
Quote from: jeffandnicole on June 07, 2016, 09:29:13 PM
Quote from: UCFKnights on June 04, 2016, 09:45:54 AM
If traffic counts are equal, choose one direction at random. Its still better for traffic then the 4 way stop and eliminates the confusion.
No, no, no.
Imagine if there was an accident at the intersection. They review the intersection and determine why one direction was flashing yellow and the other red. I don't think "Oh, we flipped a coin. Best out of 5 won." is going to fly in any engineering school or court.
Quote from: cbeach40 on June 09, 2016, 10:20:47 AM
Quote from: UCFKnights on June 08, 2016, 06:36:02 PM
Why would that matter? If there's a accident, why would they be investigating why one direction has a flasing yellow unless that somehow caused a problem?
To ensure that all responsible parties did everything they could reasonably do to prevent the accident. Making a random choice is not doing that.
I would still think that picking the more major roadway, through route, or signed highway would be an easy justification. But even if the direction assigned flashing yellow were picked randomly, that basis alone wouldn't necessarily be at issue if a crash occurred at the intersection. For a typical intersection, there'd have to be some pretty unusual circumstances involved for the red/yellow flashing to contribute to crash causes or other safety problems.
In the instance of an incident review for a collision, especially if there is a party attempting to determine fault for said collision, the state of the signal (what is it displaying) is far more important that why the signal is in that state.
It would need to be a serious crash, such as a fatal, for them to investigate why a signal had a flash mode set for a certain direction.
If it's flashing yellow for the state and red for the county road, it's a pretty easy call. But if it's two county roads, or two state roads, there would have to be a little more thought put into it. Even if it's a judgment call, judgment is usually based on an engineer's professional opinion, which should take into account numerous conditions. Random is just a 'throw the dart' type response to a legit traffic engineering decision, which would not be an advisable solution to a problem.
Quote from: cbeach40 on June 09, 2016, 10:20:47 AM
Quote from: UCFKnights on June 08, 2016, 06:36:02 PM
Why would that matter? If there's a accident, why would they be investigating why one direction has a flasing yellow unless that somehow caused a problem?
To ensure that all responsible parties did everything they could reasonably do to prevent the accident. Making a random choice is not doing that.
Of course it is. As long as they follow all the engineering standards in determining that it is safe for either direction to have a flashing yellow light, and determining that there is no preference from an engineering standpoint that one should be selected over the other, making a random choice is doing just that and entirely safe. It would not get questioned (unless there is a new piece of information).
Even if it does get investigated, it is unlikely they are going to investigate "why was it set it to flashing yellow". They're going to investigate "was the signal set in a way that violates standards or guidelines", "did the configuration of this signal contribute to the accident", "is there a missing guideline or a unique situation here that was overlooked that would help prevent this from happening in the future". All the time when I ask engineers why they made some decision, they tell me "it feels right", or when I ask why not, they tell me "it doesn't feel right", and they don't get in trouble for that.
Quote
Quote from: UCFKnights on June 08, 2016, 06:36:02 PM
Either direction having a flashing yellow is perfectly valid from an engineering standpoint,
If they both are equally valid for a yellow, then neither is valid for a flashing red.
Sure, until you apply to flashing yellow to one direction, then the other direction becomes invalid for a flashing yellow and must go to flashing red.
Quote
Quote from: UCFKnights on June 08, 2016, 06:36:02 PM
and these random decisions are done all the time.
Not too often by engineers who want to keep being engineers. ;)
This is the real world, nearly every engineer I know (and there are plenty of them) make decisions without the facts all the time because things need to get done, and there isn't a rule for it (or they don't know the rule for it because there are so many rules). Decisions all the time are made randomly and these people are successful engineers. You ask them "why'd you put this pedestal here on this corner" and the answer is "well I needed to put it somewhere" and you ask them "can we move it here?" and the answer is "sure, no problem, I just placed it randomly within the bounds of the requirements". You give it to 10 engineers you're going to get 10 different locations. As long as an engineer picks one of the valid solutions that meets all of the criteria and standards, they'll continue to be engineers. (Hell, even if they don't pick a valid solution, as long as its not really bad, they'll continue to be engineers, it typically needs to rise to the level of willful violations or gross negligence to create a problem for them)
Quote from: UCFKnights on June 09, 2016, 12:28:28 PM
Quote from: cbeach40 on June 09, 2016, 10:20:47 AM
Quote from: UCFKnights on June 08, 2016, 06:36:02 PM
Why would that matter? If there's a accident, why would they be investigating why one direction has a flasing yellow unless that somehow caused a problem?
To ensure that all responsible parties did everything they could reasonably do to prevent the accident. Making a random choice is not doing that.
Of course it is. As long as they follow all the engineering standards in determining that it is safe for either direction to have a flashing yellow light, and determining that there is no preference from an engineering standpoint that one should be selected over the other, making a random choice is doing just that and entirely safe. It would not get questioned (unless there is a new piece of information).
In court, EVERYTHING is allowed to be questioned, unless the judge throws it out.
QuoteAll the time when I ask engineers why they made some decision, they tell me "it feels right", or when I ask why not, they tell me "it doesn't feel right", and they don't get in trouble for that.
I'm not sure exactly what you do, but why would they get in trouble answering a question you asked? And being the vague comments, here, I wouldn't know what this could be in reference to. I can tell you that an engineer sitting in court, when asked "Why was the traffic signal placed in such a position", "Because it felt right" would not benefit the defense's case.
Quote
QuoteQuote
and these random decisions are done all the time.
Not too often by engineers who want to keep being engineers. ;)
This is the real world, nearly every engineer I know (and there are plenty of them) make decisions without the facts all the time because things need to get done, and there isn't a rule for it (or they don't know the rule for it because there are so many rules). Decisions all the time are made randomly and these people are successful engineers. You ask them "why'd you put this pedestal here on this corner" and the answer is "well I needed to put it somewhere" and you ask them "can we move it here?" and the answer is "sure, no problem, I just placed it randomly within the bounds of the requirements".
I don't believe any of this. You mean they just put a pedestal wherever they want, without regards to there being drainage pipes, electrical, trees, power lines, sidewalks, light fixtures, etc?
And they'll make decisions ignoring rules and laws because they don't know them?
QuoteYou give it to 10 engineers you're going to get 10 different locations. As long as an engineer picks one of the valid solutions that meets all of the criteria and standards, they'll continue to be engineers.
This is correct. But if something goes wrong, they're going to speak to the engineer who's solution they went with. The other 9 ultimately had nothing to do with it.
Quote(Hell, even if they don't pick a valid solution, as long as its not really bad, they'll continue to be engineers, it typically needs to rise to the level of willful violations or gross negligence to create a problem for them)
Isn't "not picking a valid solution" equal to a willful violation or gross negligence? Sure, maybe they'll keep their license, but that doesn't mean they're not at fault.
I wish that some signals would go back to that switching to flash mode in non peak travel times. We used to do that here in Orlando, but recently they seem to be all 24/7 operating.
Traffic counts are so detailed that it's almost impossible to find two segments next to each other that will have the same exact ADT. No engineers are picking approaches at random. And even if they did, the engineers would bullshit a technical explanation for what they did anyway.
Quote from: jeffandnicole on June 09, 2016, 01:05:36 PM
I don't believe any of this. You mean they just put a pedestal wherever they want, without regards to there being drainage pipes, electrical, trees, power lines, sidewalks, light fixtures, etc?
Of course not, that is not within the bounds of the requirements, I wrote that in the sentence you quoted. There is always separation requirements between all of the things you mentioned, so violating those requirements would not be permitted. But once all of those things are cleared, there is still often a ton of choice where to put it. Do we put it on the north side of this intersection? The south side? 50 ft away? 75 ft away? 78 ft away? As long as there is no preference, guideline, or rule being violated, any of those choices could be perfectly acceptable and the engineer is free to do it randomly. Obviously if there is a tree 50 ft away that will interfere, that would not be acceptable. Anything that violates a rule or guideline when it is possible to follow said rule or guidelines removes that choice. The real world isn't black and white like you make it seem.
Quote from: UCFKnights on June 09, 2016, 09:33:50 PM
Quote from: jeffandnicole on June 09, 2016, 01:05:36 PM
I don't believe any of this. You mean they just put a pedestal wherever they want, without regards to there being drainage pipes, electrical, trees, power lines, sidewalks, light fixtures, etc?
Of course not, that is not within the bounds of the requirements, I wrote that in the sentence you quoted. There is always separation requirements between all of the things you mentioned, so violating those requirements would not be permitted. But once all of those things are cleared, there is still often a ton of choice where to put it. Do we put it on the north side of this intersection? The south side? 50 ft away? 75 ft away? 78 ft away? As long as there is no preference, guideline, or rule being violated, any of those choices could be perfectly acceptable and the engineer is free to do it randomly. Obviously if there is a tree 50 ft away that will interfere, that would not be acceptable. Anything that violates a rule or guideline when it is possible to follow said rule or guidelines removes that choice. The real world isn't black and white like you make it seem.
Still not correct. If you put it 10 feet away from the curb, you'll need a certain length mast. If you put it 20 feet away from the curb, you'll need a different length mast. Depending on state guidelines, a 20 foot mast can be made of a certain type of material, but a 30 foot mast may need a different type of material.
10 or 20 feet, or 50 or 75 feet, means you have to run wiring for a different length.
How about pedestrian buttons and signals? If the pole is 1 foot away from the sidewalk, you can put the ped button on the post. If the pole is 10 feet away from the sidewalk, it's not useable for the ped button.
Again, there's nothing random about it. Everything they do has a reason. And everything they do affects other things related to the intersection.
And if you want to get down to it, if one is looking at rules and guidelines, then they're not making random decisions. They have justified a location based on the conditions present.
Quote from: UCFKnights on June 09, 2016, 09:33:50 PM
Quote from: jeffandnicole on June 09, 2016, 01:05:36 PM
I don't believe any of this. You mean they just put a pedestal wherever they want, without regards to there being drainage pipes, electrical, trees, power lines, sidewalks, light fixtures, etc?
Of course not, that is not within the bounds of the requirements, I wrote that in the sentence you quoted. There is always separation requirements between all of the things you mentioned, so violating those requirements would not be permitted. But once all of those things are cleared, there is still often a ton of choice where to put it. Do we put it on the north side of this intersection? The south side? 50 ft away? 75 ft away? 78 ft away? As long as there is no preference, guideline, or rule being violated, any of those choices could be perfectly acceptable and the engineer is free to do it randomly. Obviously if there is a tree 50 ft away that will interfere, that would not be acceptable. Anything that violates a rule or guideline when it is possible to follow said rule or guidelines removes that choice. The real world isn't black and white like you make it seem.
I think "randomly" isn't the word you are looking for.
Signalized intersections are carefully planned with everything laid out on roadway plans by Phase II engineers. This includes all signals, masts, handholes, and--yes, the control cabinet (we call it "tha cabinet"). Engineers also have to decide on the use of a backup power supply, where to place that, detector loops or infrared cameras, signal head placement etc. etc. But pedestals/cabinets are laid out with just as much consideration as the signal structures themselves. Keep in mind that all the wires from the detector loops will have to tie into a handhole or cabinet, so engineers will want to minimize the lengths of wire to keep things cost-efficient. As for navigating around utilities, roadway plans are often created with limited knowledge of joint utility locations, so utility companies are typically contacted by the Phase III engineers (the ones who oversee the actual construction process) and informed that they need to move their wires, cables, powerlines, gas mains, etc. out of the way of the new construction. That's the way I've seen it anyway...as an actual Phase III roadway engineer.
I haven't read all the posts in this so I don't know if it's been said - but there will never be a four-way flashing yellow. It will either be a four-way red, or two-way yellow with a two-way red crossing.
Quote from: 8.Lug on June 10, 2016, 01:55:07 AM
I haven't read all the posts in this so I don't know if it's been said - but there will never be a four-way flashing yellow. It will either be a four-way red, or two-way yellow with a two-way red crossing.
But if you're driving overseas don't assume it will be the same! Australia and (I think) most European countries use 4-way flashing yellow only.
Quote from: 8.Lug on June 10, 2016, 01:55:07 AM
I haven't read all the posts in this so I don't know if it's been said - but there will never be a four-way flashing yellow. It will either be a four-way red, or two-way yellow with a two-way red crossing.
I once saw a 3 way flashing yellow at a temp signal off of Exit 56 on NJ's I-295. Clearly an error. Yet, it remained throughout the few weeks (up to a month) is was active. Never once heard of an incident and nothing was in the news about it. In this case, those using the offramp had to turn left here (right turns split off prior to a porkchop island), so they were the ones supposed to stop, and apparently they did!
Quote from: Jet380 on June 10, 2016, 05:57:16 AM
Quote from: 8.Lug on June 10, 2016, 01:55:07 AM
I haven't read all the posts in this so I don't know if it's been said - but there will never be a four-way flashing yellow. It will either be a four-way red, or two-way yellow with a two-way red crossing.
But if you're driving overseas don't assume it will be the same! Australia and (I think) most European countries use 4-way flashing yellow only.
You guys don't even know what side of the road you're supposed to drive on!
I jest. I actually do know it's us that's on the wrong side of the road. (Driving on the left actually came about from coming up along side someone's right side to extend your right hand to greet them, which started LONG before cars even existed).
Since it's kinda relevant, here's plans I came across online for a new traffic light at an intersection in Delaware. While you don't see and hear the thought that went into where the placement of the light should go, you can see the detail presented that indicates how much they look at. http://www.deldot.gov/information/projects/centreville_safety_study/pdf/SR52_OwlsNest_TwaddellMill.pdf
Quote from: 8.Lug on June 10, 2016, 01:55:07 AM
I haven't read all the posts in this so I don't know if it's been said - but there will never be a four-way flashing yellow. It will either be a four-way red, or two-way yellow with a two-way red crossing.
Obviously you have never been to this part of the world. We only have flashing yellow. No flashing red (Which is Chinese to me), we'll put a Stop sign with the flashing yellow for the same meaning.
Quote from: kphoger on May 30, 2016, 09:07:28 PM
I've thought of this every so often. Some towns switch to red/yellow, others red/red, still others offer a mixed bag. If you can't see the cross-traffic signals, then there's no foolproof way knowing. As much as I dislike stoplights, I'd rather signals operate 24/7 than not know whether I can safely go or not.
The flash at night is not uncommon in Texas. I don't remember ever being at an intersection where I couldn't see the cross-street signals, but in this thread it sounds like that must be a problem in some areas. I'm wondering why. Are the signal hoods larger, maybe obstructing the view? Signal placement? Intersection geometrics?
Quote from: CNGL-Leudimin on June 10, 2016, 05:15:39 PM
Quote from: 8.Lug on June 10, 2016, 01:55:07 AM
I haven't read all the posts in this so I don't know if it's been said - but there will never be a four-way flashing yellow. It will either be a four-way red, or two-way yellow with a two-way red crossing.
Obviously you have never been to this part of the world. We only have flashing yellow. No flashing red (Which is Chinese to me), we'll put a Stop sign with the flashing yellow for the same meaning.
Definitely haven't been off the continent, seems kind of weird so many people here aren't from North America. But regarding your stop-sign comment - you can't have a stop sign and a full 3-color signal, it doesn't make sense. This thread is about lights that change from normal 3-color operation during the day, to flashing lights at night.
Cincinnati has many signals that go into flashing mode at 10:00 or 11:00 at night. That's the key, AT NIGHT, you know when it's DARK out, so there's no problem coming to a flashing red and seeing that the cross street has a flashing yellow. If it's a busier intersection with turn phases, or complicated geometry then it stays in RYG mode 24/7, but otherwise it's really not that complicated to give the main street a flashing yellow and the side street flashing red late at night.
Quote from: MisterSG1 on May 31, 2016, 07:52:02 AM
While brainstorming after reading a few posts, I think I know a solution that could possibly work to eliminate the ambiguity, unfortunately it would require a slight tweak of the rules.
Flashing Yellow - Proceed with caution (no change in meaning)
Flashing Red - Stop, this intersection is a FOUR WAY or ALL WAY stop
Flashing Red + Yellow - Stop, and proceed only if safe to do so, cross traffic has right of way
So if the flashing red indication fails for some reason there can be two perpendicular movements with flashing yellows? It would be easier to phase in either permanent or blank out signs stating cross traffic does not stop.
A possible change that would not require a modification to the rules or the signal hardware would be to alter the rate and pattern of flash, for example:
Flashing yellow signal has short flashes with long gaps ie:
++____++____++____++____
Flashing red signal (cross traffic does not stop) remains unchanged ie:
++++____++++____++++____
Flashing red signal (cross traffic stops) has short flashes with short gaps ie:
++__++__++__++__++__++__
Leaving the 'cross traffic does not stop' pattern unchanged means that for signals that are not upgraded, drivers will assume the most restrictive signal. Adding a different pattern for flashing yellow would also be helpful for colourblind drivers who have difficulty distinguishing red and yellow at night.
^ I don't think most motorists would pick up on the subtlety in the different flash patterns to make this viable. Besides, there are standards in the MUTCD that regulate the flash period of beacons and flashing signals (something like 'not less than 50 nor more than 60 flashes per minute').
Quote from: Jet380 on June 13, 2016, 02:31:55 AM
A possible change that would not require a modification to the rules or the signal hardware would be to alter the rate and pattern of flash, for example:
Flashing yellow signal has short flashes with long gaps ie:
++____++____++____++____
Flashing red signal (cross traffic stops) has short flashes with short gaps ie:
++__++__++__++__++__++__
Leaving the 'cross traffic does not stop' pattern unchanged means that for signals that are not upgraded, drivers will assume the most restrictive signal. Adding a different pattern for flashing yellow would also be helpful for colourblind drivers who have difficulty distinguishing red and yellow at night.
We call these flash rates "malfunctions". :biggrin: :biggrin:
How about a sign near the signal with wording to this effect "WHEN FLASHING RED CROSS TRAFFIC DOES NOT STOP"?
Quote from: theline on June 13, 2016, 02:01:12 PM
How about a sign near the signal with wording to this effect "WHEN FLASHING RED CROSS TRAFFIC DOES NOT STOP"?
But then what happens when the signal has a fault and all red flash mode?
Quote from: cbeach40 on June 13, 2016, 02:16:08 PM
Quote from: theline on June 13, 2016, 02:01:12 PM
How about a sign near the signal with wording to this effect "WHEN FLASHING RED CROSS TRAFFIC DOES NOT STOP"?
But then what happens when the signal has a fault and all red flash mode?
I'm thinking that's a rare and short-lived occurrence, while the red/yellow flashing mode happens for several hours each day. I'd suggest that it's better to have the assumption that the cross traffic doesn't stop when it does stop, rather than assuming it stops when it doesn't.
Quote from: cbeach40 on June 13, 2016, 02:16:08 PM
Quote from: theline on June 13, 2016, 02:01:12 PM
How about a sign near the signal with wording to this effect "WHEN FLASHING RED CROSS TRAFFIC DOES NOT STOP"?
But then what happens when the signal has a fault and all red flash mode?
In that case it should be a bit safer of a failure mode than potentially having two perpendicular movements flashing yellow. There might be a few awkward moments where everyone at the intersection is trying to figure out what is going on, but any accidents should occur at lower speeds.
Isn't there an option with some signal controllers to make the conflict/hard flashing default to yellow/red?
Quote from: Revive 755 on June 13, 2016, 10:38:19 PM
Quote from: cbeach40 on June 13, 2016, 02:16:08 PM
Quote from: theline on June 13, 2016, 02:01:12 PM
How about a sign near the signal with wording to this effect "WHEN FLASHING RED CROSS TRAFFIC DOES NOT STOP"?
But then what happens when the signal has a fault and all red flash mode?
In that case it should be a bit safer of a failure mode than potentially having two perpendicular movements flashing yellow. There might be a few awkward moments where everyone at the intersection is trying to figure out what is going on, but any accidents should occur at lower speeds.
If you've intentionally created an ambiguous situation, then you've failed at the one job you had.
Quote from: Revive 755 on June 13, 2016, 10:38:19 PM
Isn't there an option with some signal controllers to make the conflict/hard flashing default to yellow/red?
You could, but what happens if it fails during the PM peak? Then you've got a much, much bigger problem on your hand.
In terms of traffic engineering, this is all incredibly basic stuff. The absolutely first, and far most important rule is to never violate driver expectancy.
1. All red flash - only do this if drivers on all approaches can reasonably expect to stop
2. Red-yellow flash - only do this if
A) drivers reasonably expect to stop on the one approach,
B) drivers one the opposing road do not expect to stop, and
C) drivers on the stopping road expect cross traffic to have right-of-way
3. Remain in cycling mode - if the above criteria are not met, do not mess with it.
Traffic signals are the one control device that has the least room for error. They also have the most black and white criteria. Something is either warranted or its not. Timing is either sufficient or it's not. It's not that hard.
Quote from: Revive 755 on June 13, 2016, 10:38:19 PM
Quote from: cbeach40 on June 13, 2016, 02:16:08 PM
Quote from: theline on June 13, 2016, 02:01:12 PM
How about a sign near the signal with wording to this effect "WHEN FLASHING RED CROSS TRAFFIC DOES NOT STOP"?
But then what happens when the signal has a fault and all red flash mode?
In that case it should be a bit safer of a failure mode than potentially having two perpendicular movements flashing yellow. There might be a few awkward moments where everyone at the intersection is trying to figure out what is going on, but any accidents should occur at lower speeds.
Isn't there an option with some signal controllers to make the conflict/hard flashing default to yellow/red?
Yes. I know of one signal nearby (Forts Ferry/Wade) that has flashing yellow on one street and flashing red on the other in failure mode.
Almost every light I know of defaults to yellow/red flashing modes when not working properly.
So cbeach, I have a question, what happens at more complicated intersections if failure mode were to occur, I mean intersections which have fully protected left signals. Because if you ask me, any failure on a big intersection (like what I seen this morning at Leslie/Lake Shore, in this case all signals were simply off) can cause chaotic disorder at a major intersection.
Does every single signal flash red? Even the left turn ones?
I can recall back in 2002 on Huron Church Road in Windsor seeing one intersection displaying a flashing yellow ball for straight traffic and a flashing red ball for the fully protected left turn light, but what actually is the real standard for this.
Quote from: jeffandnicole on June 14, 2016, 01:50:06 PM
Almost every light I know of defaults to yellow/red flashing modes when not working properly.
Many of the signals in Philadelphia (at least the Center City part of it) have an all-red flash mode.
Quote from: 8.Lug on June 10, 2016, 06:02:55 PM
Quote from: CNGL-Leudimin on June 10, 2016, 05:15:39 PM
Quote from: 8.Lug on June 10, 2016, 01:55:07 AM
I haven't read all the posts in this so I don't know if it's been said - but there will never be a four-way flashing yellow. It will either be a four-way red, or two-way yellow with a two-way red crossing.
Obviously you have never been to this part of the world. We only have flashing yellow. No flashing red (Which is Chinese to me), we'll put a Stop sign with the flashing yellow for the same meaning.
Definitely haven't been off the continent, seems kind of weird so many people here aren't from North America. But regarding your stop-sign comment - you can't have a stop sign and a full 3-color signal, it doesn't make sense. This thread is about lights that change from normal 3-color operation during the day, to flashing lights at night.
Many countries post secondary traffic control devices below the traffic signals, to indicate what the approaching driver should do, should the signals be dark, or, should they be flashing yellow. Typically, the other cross-road won't have any secondary traffic control device, because they're the priority road (the road with the most traffic), and if dark or flashing yellow, they can proceed without stopping.
As an example, the signal on the left has priority when dark or flashing yellow (the priority sign below the signal shows this); the signal on the right must stop when dark or flashing yellow:
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Finternational.fhwa.dot.gov%2Fpubs%2Fpl03020%2Fimages%2Ffig4_6.jpg&hash=47f9c0bafb21cd6ac62f0be90d00300fba209cc1) (https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fdwpicture.com.au%2Fphotos%2F20931b.jpg&hash=27f61f8fb29ab3c66e82ff976f0dd91e08563004)
Quote from: MisterSG1 on June 14, 2016, 02:34:30 PM
So cbeach, I have a question, what happens at more complicated intersections if failure mode were to occur, I mean intersections which have fully protected left signals. Because if you ask me, any failure on a big intersection (like what I seen this morning at Leslie/Lake Shore, in this case all signals were simply off) can cause chaotic disorder at a major intersection.
Does every single signal flash red? Even the left turn ones?
Current Ontario standard is that signals with left turn arrows should not go into flash mode.
Per the OTM:
Standardized Flashing Operation
Traffic control signals that do not use left-turn arrow
heads (excluding types 8, 8A, 9 and 9A), may be
switched from their normal phase indication to
flashing operation. Three modes of flashing
operation are normally used:
- Start-up flash — the signals are commonly
started with flashing ambers on the main road
and flashing reds on the side roads.
- Emergency flash — when a conflict is detected,
the signals are commonly flashed in an all-red
or "red-red" mode if the controller flashers have
that capability. The red-red mode has a safety
advantage over the red-amber mode (reds on
side road; ambers on main roads) but the red-amber
mode is an acceptable alternative and
is considered safer on roads with posted
speeds of 80 km/h and above and with light
side road traffic since fewer stops are required.
- Timed flash — the signals may be programmed
to operate in the red-red or red-amber mode
during various periods of the night or of the
week, for special events or during a Police
over-ride mode of operation.
It should be noted, however, that flashing operations
within a traffic control signal cabinet are generally
wired as either red-red or amber-red and the flash
circuit cannot be changed from one mode to
another without re-wiring the necessary circuits.
Planned flashing operation of signalized
intersections may be advantageous to traffic flow
under some specific and limited conditions. Flashing
operation may be of assistance in reducing vehicle
delay and stops in pretimed networks at locations
with poor signal spacing. Planned flash is only
applicable under conditions of very light minor street
traffic such as during the overnight period, or in
locations that have extended periods of low volume
such as accesses to an industrial area. Caution
should be used in the application of planned flashing
signal operation. It should only be used if:
- Sidestreet traffic is very light (less than
200 vph combined for both directions).
- The traffic signals operate fixed time (i.e., no
side street vehicular or pedestrian actuation).
- The planned flash mode is amber flash for the
main street, red flash for the side street.
- There is no emergency vehicle pre-emption
capability.
- Pedestrian volumes crossing the main street
during planned flashing period are very light.
- The major roadway is not channelized and has
no more than four lanes.
If planned signal flash is implemented, regular safety
reviews should be conducted to compare the
occurrence of collisions during the flash hours at
intersections with planned flash with similar
locations without planned flash.
The standard flashing red or flashing amber traffic
control signal indication shall be at a rate of not
more than 60 and not less than 50 ON and OFF
flashes per minute, with the length of each ON
period approximately equal to the length of each
OFF period. The flash rate is slower than that used
for flashing advance green indications.
Additionally MisterSG1, per our discussion at the Toronto meet this past weekend, flashing green ball was used in place of advance LT and Thru, the equivalent to a solid green ball+LT arrow. I'm sure ambiguity that you mentioned there was just one of the many reasons why that practice was recommended to be discontinued.
The above does not apply in the States. I'm not certain about what the MUTCD says (nor do I feel like digging through it), but from experience, I can say that fully protected signals can (and occasionally do) go into flash mode. Either the red arrow flashes or there is an otherwise-unused red or yellow ball that flashes. Examples of the latter include these in Burlington, Massachusetts (https://www.google.com/maps/@42.4793367,-71.2162493,3a,41y,144.59h,91.81t/data=!3m6!1e1!3m4!1s-Ap_zU3fq_sKaBle9PovZQ!2e0!7i13312!8i6656) and this one in Syracuse, New York (https://www.google.com/maps/@43.0424431,-76.0675352,3a,45.1y,338.16h,84.29t/data=!3m6!1e1!3m4!1ss6YfaEIRSXlucD6qxA4GtQ!2e0!7i13312!8i6656). The latter very well might flash at night, but I have no intention to ever be in the area when it might ever go into flash mode (and I would not suggest that anyone tries). If you're familiar with Erie Boulevard in Syracuse, you know what I mean.
Quote from: cl94 on June 14, 2016, 11:49:39 PM
Either the red arrow flashes or there is an otherwise-unused red or yellow ball that flashes. Examples of the latter include these in Burlington, Massachusetts (https://www.google.com/maps/@42.4793367,-71.2162493,3a,41y,144.59h,91.81t/data=!3m6!1e1!3m4!1s-Ap_zU3fq_sKaBle9PovZQ!2e0!7i13312!8i6656)...
In that example, do both left turn lanes show a flashing orb? Does this qualify as a dual permissive left, at night?
Quote from: jakeroot on June 15, 2016, 12:26:17 AM
Quote from: cl94 on June 14, 2016, 11:49:39 PM
Either the red arrow flashes or there is an otherwise-unused red or yellow ball that flashes. Examples of the latter include these in Burlington, Massachusetts (https://www.google.com/maps/@42.4793367,-71.2162493,3a,41y,144.59h,91.81t/data=!3m6!1e1!3m4!1s-Ap_zU3fq_sKaBle9PovZQ!2e0!7i13312!8i6656)...
In that example, do both left turn lanes show a flashing orb? Does this qualify as a dual permissive left, at night?
Knowing that intersection, I doubt it goes into flash mode at night (can someone in Eastern Massachusetts confirm this?). I assume it's there for emergencies. Every protected signal in the area has a normally-unused ball section.
Quote from: cl94 on June 15, 2016, 12:56:15 AM
Quote from: jakeroot on June 15, 2016, 12:26:17 AM
Quote from: cl94 on June 14, 2016, 11:49:39 PM
Either the red arrow flashes or there is an otherwise-unused red or yellow ball that flashes. Examples of the latter include these in Burlington, Massachusetts (https://www.google.com/maps/@42.4793367,-71.2162493,3a,41y,144.59h,91.81t/data=!3m6!1e1!3m4!1s-Ap_zU3fq_sKaBle9PovZQ!2e0!7i13312!8i6656)...
In that example, do both left turn lanes show a flashing orb? Does this qualify as a dual permissive left, at night?
Knowing that intersection, I doubt it goes into flash mode at night (can someone in Eastern Massachusetts confirm this?). I assume it's there for emergencies. Every protected signal in the area has a normally-unused ball section.
I can recall (over 20 years ago) such signals with the yellow ball in the left turn signal flashing on weekends even, with the yellow ball flashing. It may not have been intended to be for non-emergency use, but practice was that it was used that way when the signals went on flashing for off-peak times.
The existence of flashing yellow arrow as something with an actual meaning now probably makes adding the yellow ball moot.
Here in Springdale, there's actually a signal 2 blocks away that, after a certain time of night, switches to a flashing red/flashing yellow configuration. The flashing red is on the main road, while the yellow is for the minor cross streets.