It is ridiculous to sit in the left lane of an urban street with no traffic coming in the opposite direction for miles and not being able to make a left turn until the lights cycle. I can understand why the DOTs disallow left turns without the arrow in heavy traffic, but why not program the signals to have a regular green light from, say, 10pm to 7am. Yes, I have been the victim of the dreaded no turns on red light many times and yes, I've blown through them many times. The law should be written that if there is time to make the turn safely, then make the turn. I would go even further and say the state legislatures should ban left turn arrows except on dangerous intersections and only during the day.
I've been a victim of many of these and eventually turned on red at night as well. IMO, situations like these could use a FYA. The signal could be programmed to be protected only during peak hours, then switched to FYA the rest of the time; only turning red when the cross street has green.
This intersection (https://www.google.ca/maps/@40.21392,-74.765203,3a,42.1y,235.13h,92.41t/data=!3m4!1e1!3m2!1sewD-TckdVA4vS1qW1n0O7A!2e0) has caused me to wait UNTIL SOMEONE PULLED UP ON THE OTHER SIDE OF THE INTERSECTION BEFORE CHANGING. That's NOT okay. It took about 3 1/2 minutes before the signal did change, and considering the city I was in I thought about blowing through it when there was nothing remotely dangerous about doing it, but I've lately been seeing more actual Trenton PD cars scattered throughout the streets, so I didn't feel like chancing it.
But I agree with bugo - these things need a fucking change. I can't believe I had to sit in a turn lane for nearly 4 minutes because the cycle was dependent on someone being at the opposite side of the intersection.
Quote from: Zeffy on April 02, 2015, 09:54:40 AM
This intersection (https://www.google.ca/maps/@40.21392,-74.765203,3a,42.1y,235.13h,92.41t/data=!3m4!1e1!3m2!1sewD-TckdVA4vS1qW1n0O7A!2e0) has caused me to wait UNTIL SOMEONE PULLED UP ON THE OTHER SIDE OF THE INTERSECTION BEFORE CHANGING. That's NOT okay. It took about 3 1/2 minutes before the signal did change, and considering the city I was in I thought about blowing through it when there was nothing remotely dangerous about doing it, but I've lately been seeing more actual Trenton PD cars scattered throughout the streets, so I didn't feel like chancing it.
Welcome to road biking 101.
^^ I only see traffic detectors in the pavement in only 1 of the left-turn lanes and I don't see any optical detectors. Somebody dropped the ball there.
You want flashing yellow lights.
And NE2's right -- bikes have a hell of a time trying to trip a protected green arrow, even when the sensor wires are obvious and even when the city paints where the bike's supposed to go.
Quote from: Bickendan on April 02, 2015, 10:57:43 AM
You want flashing yellow lights.
And NE2's right -- bikes have a hell of a time trying to trip a protected green arrow, even when the sensor wires are obvious and even when the city paints where the bike's supposed to go.
I would love a FYA here. It would work way better than this shit. Actually, a lot of Trenton's signals seem poorly timed. Maybe it was just that the traffic is a lot less on Sunday then other days so the lights are timed for the busy days. Which is stupid.
EDIT: Not to mention this fad is sweeping Hillsborough. Two of our intersections have been replaced with these monstrosities. Sometimes they work decent. Other times I'll go other ways to avoid them.
Quote from: signalman on April 02, 2015, 04:20:04 AM
I've been a victim of many of these and eventually turned on red at night as well. IMO, situations like these could use a FYA. The signal could be programmed to be protected only during peak hours, then switched to FYA the rest of the time; only turning red when the cross street has green.
Around here, a lot of the intersections with a left turn arrow part of the cycle just turn to straight green when the protected phase ends. Seems to work pretty well.
This (https://www.google.com/maps/@40.453989,-79.912352,3a,45.8y,314.53h,80.41t/data=!3m4!1e1!3m2!1ssGNLA5ukSk6jxestKfMJzQ!2e0) is a big one, and it's either all green, red with green left-turn arrow (during the protected phase), or all red. The left-turning traffic is never prohibited from making the turn while the traffic alongside it is allowed to move.
I hate the intersections that have the left arrow AND the traffic going straight. It turns red and the other direction does the same. I prefer the MN signals: The left turners go first and when the line subsides all straight traffic goes. Left turners can still go, unprotected.
This morning I got stuck at the light leaving my neighborhood because I got there just 15 or 20 seconds too late: Traffic coming the other way on my street had gotten a green and if I'm not there before that green comes on, the light makes me wait through the whole light cycle before my side will get a green. I hate that. Waste of time, waste of gas idling, bad for the air to have people idling....if it had been midday with nobody around I might have run the light, but there were too many people on the other street to risk it in case one was an unmarked cop or some such. I wish the detection loop could trigger the green mid-cycle. Doesn't need to be an arrow. The current signal head there is the usual Virginia doghouse (huge improvement from when I moved to my house in 2001 and neither direction had an arrow, just straight green circles both at the same time).
Part of the problem is duel (and even triple) left turn lanes are becoming more common to combat congestion. Agencies are extremely hesitant to provide permissive left turns at intersections with dual left turns. Sure, you get increased capacity at 5PM but at 2AM drivers are needlessly waiting at a protected left turn.
Quote from: tradephoric on April 02, 2015, 11:29:33 AM
Part of the problem is duel (and even triple) left turn lanes are becoming more common to combat congestion. Agencies are extremely hesitant to provide permissive left turns at intersections with dual left turns. Sure, you get increased capacity at 5PM but at 2AM drivers are needlessly waiting at a protected left turn.
This is understandable especially when there's also a dual turn in the other direction. Sometimes it's hard enough to see around large vehicle in a single permissive turn lane. Dual lanes would just make that worse.
Regarding your very valid point about late nights, I miss the days when some traffic lights around here used to go on flash overnight, especially lights outside strip malls and the like. The street would have a flashing yellow and the shopping area a flashing red.
Quote from: texaskdog on April 02, 2015, 11:25:07 AM
I hate the intersections that have the left arrow AND the traffic going straight. It turns red and the other direction does the same. I prefer the MN signals: The left turners go first and when the line subsides all straight traffic goes. Left turners can still go, unprotected.
Florida has been doing that for years. I argued with a friend of mine (now retired for health reasons) who worked for Orange County Traffic Engineering in Signal Maintenance, that the way signals in Florida now have the left turn arrow at the same time as the through sucks. He said to me that no matter where the left turn cycles, the same amount of red and green time exists. I tend to disagree as the timing in his department is not doing that.
What is worse is the placement in rotation for the left turn protected left changes throughout the day. Sometimes its at first when the through movement goes green and then at another part of the day its at the end of the through cycle. Sometimes it changes from day to day as one day on John Young Parkway in Orlando at Town Center Boulevard it will be at the start of the through and go there the same time another day (weekday I mind you, as I can see the difference between Saturday and Monday for example) it will be at the end of the through movement.
To get to the OP, yes I hate it when we are forced to sit there and wait for a light to change when there is absolutely NO oncoming traffic! It happens a lot to me and yes I can see part time left turn signals at those times in the day. In fact Delaware does it where they will flash the red ball for the protected left turn signal and allow the motorist to turn left at certain off peak times after a full stop that no one ever makes.
Quote from: 1995hoo on April 02, 2015, 11:40:19 AM
Quote from: tradephoric on April 02, 2015, 11:29:33 AM
Part of the problem is duel (and even triple) left turn lanes are becoming more common to combat congestion. Agencies are extremely hesitant to provide permissive left turns at intersections with dual left turns. Sure, you get increased capacity at 5PM but at 2AM drivers are needlessly waiting at a protected left turn.
This is understandable especially when there's also a dual turn in the other direction. Sometimes it's hard enough to see around large vehicle in a single permissive turn lane. Dual lanes would just make that worse.
Regarding your very valid point about late nights, I miss the days when some traffic lights around here used to go on flash overnight, especially lights outside strip malls and the like. The street would have a flashing yellow and the shopping area a flashing red.
Alternative solution is for sensors to automatically trip the signal the moment a car (or bike) hits the sensor during the overnight phases.
Or go back to flashing the signals at night. We do that for some between 2 AM and 5 AM on Orange Blossom Trail and allow free movements on OBT and just a normal STOP sign type of deal for the side roads.
Quote from: Zeffy on April 02, 2015, 09:54:40 AM
This intersection (https://www.google.ca/maps/@40.21392,-74.765203,3a,42.1y,235.13h,92.41t/data=!3m4!1e1!3m2!1sewD-TckdVA4vS1qW1n0O7A!2e0) has caused me to wait UNTIL SOMEONE PULLED UP ON THE OTHER SIDE OF THE INTERSECTION BEFORE CHANGING. That's NOT okay. It took about 3 1/2 minutes before the signal did change, and considering the city I was in I thought about blowing through it when there was nothing remotely dangerous about doing it, but I've lately been seeing more actual Trenton PD cars scattered throughout the streets, so I didn't feel like chancing it.
But I agree with bugo - these things need a fucking change. I can't believe I had to sit in a turn lane for nearly 4 minutes because the cycle was dependent on someone being at the opposite side of the intersection.
Quote from: Big John on April 02, 2015, 10:12:15 AM
^^ I only see traffic detectors in the pavement in only 1 of the left-turn lanes and I don't see any optical detectors. Somebody dropped the ball there.
I travel thru this intersection at least 4 times a week. I'm guessing what you experienced is called "a malfunction".
In my experiences, this intersection works normally. Obviously, when motorists are in the opposing left turn lanes, both sides will get the left turn arrow. But I've been at the intersection where only one side or the other has a vehicle, and just that left turn light has turned green.
As far as the lack of traffic detectors, take a look at GSV again. They are there on both sides. The intersection was recently reconstructed and new pavement put down on one side of the intersection which allows them to be more easily seen, but they exist on both left turn lanes.
https://goo.gl/maps/2Nvtl & https://goo.gl/maps/EHL03
It's also a good time to bring up this: If something doesn't appear right, it probably isn't. I don't know of an intersection anywhere that is designed to mandate traffic be on both sides of the intersection, because you could go for several hours at night without another car needing to make an opposing movement.
Sometimes it seems like protected left turns are installed at random. You'll go through three or four intersections with permitted/protected (doghouses) or FYA's, then all of a sudden you hit one with a protected left. I've started to figure out that sight distance issues are probably the reason most protected lefts are installed amongst a sequence of doghouses or FYAs.
I find this to be a pretty minor inconvenience, and that may very well be because it seems to be written in the local DNA here that anyone who can race into the intersection first has the right-of-way to turn left, never mind how close or heavy the oncoming traffic. That drives me so up a wall that I'll take a few minutes delay in my day to hold these impatient children someplace safe until the rest of us are out of the way.
Quote from: Pete from Boston on April 02, 2015, 01:26:25 PM
I find this to be a pretty minor inconvenience, and that may very well be because it seems to be written in the local DNA here that anyone who can race into the intersection first has the right-of-way to turn left, never mind how close or heavy the oncoming traffic. That drives me so up a wall that I'll take a few minutes delay in my day to hold these impatient children someplace safe until the rest of us are out of the way.
Ah yes, the Massachusetts left. Remember, the right-of-way belongs to whoever more aggressively pursues it.
I'm more bothered by the lack of protected left turn arrows at intersections that need them. Traffic is so heavy there's no chance to turn left during the green phase, so people wanting to turn run the yellow and collide with oncoming traffic also running the yellow.
Quote from: 1995hoo on April 02, 2015, 11:40:19 AM
Quote from: tradephoric on April 02, 2015, 11:29:33 AM
Part of the problem is duel (and even triple) left turn lanes are becoming more common to combat congestion. Agencies are extremely hesitant to provide permissive left turns at intersections with dual left turns. Sure, you get increased capacity at 5PM but at 2AM drivers are needlessly waiting at a protected left turn.
This is understandable especially when there's also a dual turn in the other direction. Sometimes it's hard enough to see around large vehicle in a single permissive turn lane. Dual lanes would just make that worse.
Regarding your very valid point about late nights, I miss the days when some traffic lights around here used to go on flash overnight, especially lights outside strip malls and the like. The street would have a flashing yellow and the shopping area a flashing red.
Not to rub it in, but it's commonplace for signals to flash at night in SE Michigan. There are 15 traffic signals on US24 between I-75 & Telegraph. Of these 15 signals, 11 of them flash at night. Many of the signals that go into flash are full blown 4-phase signals with left turn phases. Even the I-75 off-ramp signals will go into flash at night.
Quote from: kkt on April 02, 2015, 02:00:25 PM
I'm more bothered by the lack of protected left turn arrows at intersections that need them. Traffic is so heavy there's no chance to turn left during the green phase, so people wanting to turn run the yellow and collide with oncoming traffic also running the yellow.
Just happened the other day at SE 26th and Powell (US 26) here in Portland. Car tried to turn left from 26th onto Powell, hit/got hit by a car running the yellow or red going the other way. Made worse that Powell Park's on one corner of the intersection and Cleveland High School's on the opposite corner.
Quote from: 1995hoo on April 02, 2015, 11:29:10 AM
This morning I got stuck at the light leaving my neighborhood because I got there just 15 or 20 seconds too late: Traffic coming the other way on my street had gotten a green and if I'm not there before that green comes on, the light makes me wait through the whole light cycle before my side will get a green. I hate that. Waste of time, waste of gas idling, bad for the air to have people idling....if it had been midday with nobody around I might have run the light, but there were too many people on the other street to risk it in case one was an unmarked cop or some such. I wish the detection loop could trigger the green mid-cycle. Doesn't need to be an arrow. The current signal head there is the usual Virginia doghouse (huge improvement from when I moved to my house in 2001 and neither direction had an arrow, just straight green circles both at the same time).
The light by my apartment is red for 1:40. The cycle rarely has a car going through at 6:20 am. When DST first kicked in the lights blinked for 2 days, it was SO NICE!!!
Norman has the opposite problem. We have a bunch of intersections that go to FYA during peak hours when a protected left would be really handy. So you get one car creep into the intersection, get stuck there while tons of oncoming traffic passes, and then either finally go in the last few seconds of the cycle once the herd passes, or else have to book it out of the intersection when the light turns red and cross traffic gets a green. It's especially maddening because green arrows are present in the signal heads, they just never come on.
Quote from: Bickendan on April 02, 2015, 12:13:18 PM
Alternative solution is for sensors to automatically trip the signal the moment a car (or bike) hits the sensor during the overnight phases.
That's how it's done, for the most part, in California where the vast majority of left turns are protected.
Quote from: Bickendan on April 02, 2015, 10:57:43 AM
You want flashing yellow lights.
And NE2's right -- bikes have a hell of a time trying to trip a protected green arrow, even when the sensor wires are obvious and even when the city paints where the bike's supposed to go.
I think Idaho stops should be legal. (Treat stop signs as yield signs on a bike; treat red traffic lights as stop signs).
Bikes have a harder time to accelerate, so if they get a head start before the light turns green if it's safe and then pull into the bike lane, it doesn't clog car traffic as much. Washington just passed a new law citing that bikes can legally run reds only if it's safe and they waited 2 minutes. Personally, as a driver and a cyclist, I think that's a bit ridiculous.
I just had one instance where the OP was talking about and more. Not only did I have to wait to turn left indefinitely to go from WB FL 50 to the Florida Turnpike ramp in Oakland, FL with no other traffic, but when the light did turn red for the other side of the road was when traffic finally approached the intersection on the opposite side.
Basically I not only had the chance to go freely while waiting for the light, but the other vehicles approaching had to stop unnecessarily as well. If the light turned green for me when no one was approaching, we would have made the cycle and it would have been green for those other vehicles as well.
The problem is the fact that everyone thinking that timing long greens is like law of the land, so they carelessly set the lights as well to give long greens for any arterial with high traffic counts. Now that sounds easy, but the thing is the when part. It may have high numbers, but you can break that down evenly over time being traffic is not steady all day long in some areas.
Yes, at rush hour or roads that have steady traffic flow the long green will work for busy arterials. During the other times when you have gaps in flows especially on high count roads where the gaps can last longer than 20-30 seconds at certain time periods, they can program the signals green time much shorter. Or better yet, how about letting the computer do the thinking! If the detector loops figure out that the amount of vehicles within x amount times is low, then automatically cut the green time!
I've found this to be a pretty annoying problem at interstate off ramps that don't receive a lot of traffic. People making right turns can easily yield, but people making left turns have to wait and wait and wait even though there are no cars coming. I suppose it's technically not quite the same thing since no protected lights are involved, but really, for the most part and depending on the kind of interchange involved, if you exit the interstate and are not turning right, you're going to turn left.
Quote from: bugo on April 02, 2015, 02:21:50 AM
It is ridiculous to sit in the left lane of an urban street with no traffic coming in the opposite direction for miles and not being able to make a left turn until the lights cycle. I can understand why the DOTs disallow left turns without the arrow in heavy traffic, but why not program the signals to have a regular green light from, say, 10pm to 7am. Yes, I have been the victim of the dreaded no turns on red light many times and yes, I've blown through them many times. The law should be written that if there is time to make the turn safely, then make the turn. I would go even further and say the state legislatures should ban left turn arrows except on dangerous intersections and only during the day.
You need to drive in Tucson more. Tucson does things differently than most cities, in that it's a rarity to have a protective left turn signal anywhere in the city limits. There are any intersections where there are dual left turn lanes that have permissive/protected left turns 24/7.
Quote from: kkt on April 02, 2015, 02:00:25 PM
I'm more bothered by the lack of protected left turn arrows at intersections that need them. Traffic is so heavy there's no chance to turn left during the green phase, so people wanting to turn run the yellow and collide with oncoming traffic also running the yellow.
If currently there is no protected left phase, I'd imagine adding a permissive green arrow would do the trick without going full on protected. Would be much more efficient.
Around here, it seems sometimes its tied to when the intersection traffic signal is installed. If they're put up one at a time, they seem satisified with permissive lefts. For the ones that get added during a road expansion, its usually a protected left. No idea why.
I personally don't think protected lefts with immediate change at night is a good solution. I find myself all the time going straight at the speed limit, an empty road ahead, except one pesky car just pulling over the sensor as I'm going straight, and I end up having to stop at every light. A permissive left would probably allow them to go in front of me without stopping, or at least go behind me with a very simliar stopping time to what the light is causing. I noticed in Palm Beach County, several lights either require stacking of 2-3 cars to trigger a green arrow (for both left and right turn lanes), or require a car to be waiting for a certain amount of time, usually about 10 seconds, or both combined. I found that worked very well.
Quote from: myosh_tino on April 03, 2015, 03:16:20 PM
Quote from: Bickendan on April 02, 2015, 12:13:18 PM
Alternative solution is for sensors to automatically trip the signal the moment a car (or bike) hits the sensor during the overnight phases.
That's how it's done, for the most part, in California where the vast majority of left turns are protected.
That's how it's done in most of Europe too. Are automatic/dynamic signals really that uncommon in the US?
Quote from: riiga on April 06, 2015, 06:58:57 AM
Quote from: myosh_tino on April 03, 2015, 03:16:20 PM
Quote from: Bickendan on April 02, 2015, 12:13:18 PM
Alternative solution is for sensors to automatically trip the signal the moment a car (or bike) hits the sensor during the overnight phases.
That's how it's done, for the most part, in California where the vast majority of left turns are protected.
That's how it's done in most of Europe too. Are automatic/dynamic signals really that uncommon in the US?
They are...to a point. If the thru route also has an active walk signal, the signal can't simply turn yellow/red once someone enters the left turn lane or side street. The signal has to cycle down to complete the walk phase first.
Same thing if someone has just used the left turn lane and another car enters it after the turn light goes red...the straight signal isn't going to go green for just a few seconds; it has to complete its cycle again.
If none of these factors exist, and a car pulls up, then yes the signal will instantly trip if it's programmed to do so.
Quote from: jeffandnicole on April 06, 2015, 12:13:44 PM
They are...to a point. If the thru route also has an active walk signal, the signal can't simply turn yellow/red once someone enters the left turn lane or side street. The signal has to cycle down to complete the walk phase first.
Don't forget who's to blame for this: drivers who don't bother to let pedestrians finish crossing.
Quote from: jeffandnicole on April 06, 2015, 12:13:44 PM
They are...to a point. If the thru route also has an active walk signal, the signal can't simply turn yellow/red once someone enters the left turn lane or side street. The signal has to cycle down to complete the walk phase first.
Yeah, same here. Pedestrian signals need to finish their cycle if they're in use. Walk signals aren't part of every cycle though, they're on-demand by pushing the button, which would allow a short dynamic left turn if no one needed to cross in the current cycle.
Quote from: jeffandnicole on April 06, 2015, 12:13:44 PM
Same thing if someone has just used the left turn lane and another car enters it after the turn light goes red...the straight signal isn't going to go green for just a few seconds; it has to complete its cycle again.
If there are no cars using the straight lane it would change back to red here, and allow the left lane to turn. That's the beauty of dynamic signals and cycles.
Do what people do in NYC. Ignore the WALK and just cross!
Quote from: roadman65 on April 06, 2015, 02:20:18 PM
Do what people do in NYC. Ignore the WALK and just cross!
Requiring drivers to do what drivers therefore have to do in NYC–ignore pedestrians just a few feet away from the car and just turn.
Yep. In NYC (upper Manhattan especially), if you don't cut off the opposing direction of traffic and mow down any pedestrians crossing, people will blare their horns at you continuously.
Quote from: riiga on April 06, 2015, 06:58:57 AM
Quote from: myosh_tino on April 03, 2015, 03:16:20 PM
Quote from: Bickendan on April 02, 2015, 12:13:18 PM
Alternative solution is for sensors to automatically trip the signal the moment a car (or bike) hits the sensor during the overnight phases.
That's how it's done, for the most part, in California where the vast majority of left turns are protected.
That's how it's done in most of Europe too. Are automatic/dynamic signals really that uncommon in the US?
Problem with these is that during low traffic periods, you often have one car coming in the green direction, a car pulls up to the red light and it cycles to stop the first car. Even more frustrating when the second car is turning right and could have just gone after the first car passed. We have an expressway in Norman configured like this and it's annoying to have to come to a complete stop from 50 mph so one random person can turn right.
If the lights are set to flash, it eliminates unnecessary stops.
Quote from: Scott5114 on April 03, 2015, 05:02:21 AM
Norman has the opposite problem. We have a bunch of intersections that go to FYA during peak hours when a protected left would be really handy. So you get one car creep into the intersection, get stuck there while tons of oncoming traffic passes, and then either finally go in the last few seconds of the cycle once the herd passes, or else have to book it out of the intersection when the light turns red and cross traffic gets a green. It's especially maddening because green arrows are present in the signal heads, they just never come on.
Maybe it would work but you always get behind some douche who can't drive and is scared to death of making a turn that takes 3 seconds when they have a 10 second break. So tired of people who can't drive.
Quote from: Pete from Boston on April 06, 2015, 04:52:08 PM
Quote from: roadman65 on April 06, 2015, 02:20:18 PM
Do what people do in NYC. Ignore the WALK and just cross!
Requiring drivers to do what drivers therefore have to do in NYC–ignore pedestrians just a few feet away from the car and just turn.
Even if pedestrians followed the signals, you'd never be able to turn if you stopped whenever a pedestrian was in the crosswalk because there's
always someone in the crosswalk
Quote from: NE2 on April 06, 2015, 01:11:42 PM
Quote from: jeffandnicole on April 06, 2015, 12:13:44 PM
They are...to a point. If the thru route also has an active walk signal, the signal can't simply turn yellow/red once someone enters the left turn lane or side street. The signal has to cycle down to complete the walk phase first.
Don't forget who's to blame for this: drivers who don't bother to let pedestrians finish crossing.
This doesn't even make sense for the situation. If the pedestrian is in the walkway during the walk signal, the only cars prohibiting the peds from crossing would be right turning vehicles. The left turning vehicles would still have a red left arrow until the ped phase is completed. And even then, the opposing thru light would need to cycle yellow and red before the left arrow turns green. It would have to be a steady stream of vehicles all ignoring the ped and their eventual red light for the ped not to be able to complete the crossing.
If drivers correctly waited, walk phases wouldn't need to be so long.
Huh? The walk phase is pre-determined - either by default (Walk symbol is lit until cross traffic appears) or by specific time. Once it goes into countdown mode, there's no turning back. This is all determined by the length of the crosswalk and time calculated to cross that length of intersection. There's no sensor there to determine a walker is in the middle of a crosswalk.
Quote from: Scott5114 on April 06, 2015, 08:39:22 PM
Problem with these is that during low traffic periods, you often have one car coming in the green direction, a car pulls up to the red light and it cycles to stop the first car. Even more frustrating when the second car is turning right and could have just gone after the first car passed. We have an expressway in Norman configured like this and it's annoying to have to come to a complete stop from 50 mph so one random person can turn right.
If the lights are set to flash, it eliminates unnecessary stops.
You could have a right turn signal. Or a slip lane with yield signs. Or priority/far away detectors for the expressway.
Quote from: jeffandnicole on April 07, 2015, 06:37:18 AM
Huh? The walk phase is pre-determined - either by default (Walk symbol is lit until cross traffic appears) or by specific time. Once it goes into countdown mode, there's no turning back. This is all determined by the length of the crosswalk and time calculated to cross that length of intersection. There's no sensor there to determine a walker is in the middle of a crosswalk.
And if drivers were willing to wait for peds to clear, the time calculated to cross could be shortened, since not all peds cross at the same speed.
To make it all the more clear, @NE2 has been referring to the cultural phenomenon of drivers not being willing to wait for late-coming or slow pedestrians to clear the crosswalk. This, his argument goes, is precisely why pedestrian countdown times are so long: we time them to make absolutely sure that a one-legged sloth can make it from curb to curb before cross traffic gets a green light. Were drivers more willing to wait longer on occasion, then two things could happen: (1) the preset countdown time could be reduced to a more average walking pace, and (2) we could possibly allow the countdown to be interrupted by the arrival of a vehicle on the cross street.
This is, if I'm on the same page s @NE2, what was meant in saying that it's drivers' fault that our stoplights are so un-dynamic. It's a general cultural thing.
Quote from: NE2 on April 07, 2015, 07:34:00 AM
And if drivers were willing to wait for peds to clear, the time calculated to cross could be shortened, since not all peds cross at the same speed.
Yes, if all users put aside their personal desires and could sort out the most effective way to prioritize the various needs of the various parties at the intersection, we wouldn't need traffic signals.
But we do.
Quote from: Pete from Boston on April 07, 2015, 09:00:29 AM
Quote from: NE2 on April 07, 2015, 07:34:00 AM
And if drivers were willing to wait for peds to clear, the time calculated to cross could be shortened, since not all peds cross at the same speed.
Yes, and if all users put aside their personal desires and could sort out the most effective way to prioritize the various needs of the various parties at the intersection, we wouldn't need traffic signals.
But we do.
If both pedestrians and drivers exercised simple common sense and common decency, then things like 20-30 second ped countdowns would be unnecessary.
Quote from: kphoger on April 07, 2015, 09:04:24 AM
Quote from: Pete from Boston on April 07, 2015, 09:00:29 AM
Quote from: NE2 on April 07, 2015, 07:34:00 AM
And if drivers were willing to wait for peds to clear, the time calculated to cross could be shortened, since not all peds cross at the same speed.
Yes, and if all users put aside their personal desires and could sort out the most effective way to prioritize the various needs of the various parties at the intersection, we wouldn't need traffic signals.
But we do.
If both pedestrians and drivers exercised simple common sense and common decency, then things like 20-30 second ped countdowns would be unnecessary.
Perhaps we need pedestrian ed classes (ped ed?) alongside driver's ed in school. And a flashing "don't be stupid" phase.
Quote from: Pete from Boston on April 07, 2015, 09:40:21 AM
Quote from: kphoger on April 07, 2015, 09:04:24 AM
Quote from: Pete from Boston on April 07, 2015, 09:00:29 AM
Quote from: NE2 on April 07, 2015, 07:34:00 AM
And if drivers were willing to wait for peds to clear, the time calculated to cross could be shortened, since not all peds cross at the same speed.
Yes, and if all users put aside their personal desires and could sort out the most effective way to prioritize the various needs of the various parties at the intersection, we wouldn't need traffic signals.
But we do.
If both pedestrians and drivers exercised simple common sense and common decency, then things like 20-30 second ped countdowns would be unnecessary.
Perhaps we need pedestrian ed classes (ped ed?) alongside driver's ed in school. And a flashing "don't be stupid" phase.
Since the countdown is based on the speed of a slower-than-average walker, the only way to reduce the amount of time would be to only permit faster walkers to cross intersections.
Quote from: jeffandnicole on April 07, 2015, 09:45:48 AM
Since the countdown is based on the speed of a slower-than-average walker, the only way to reduce the amount of time would be to only permit faster walkers to cross intersections.
...slower walkers would still be in the intersection when it changes to don't walk. But if drivers were actually willing to wait for slower peds to clear, that wouldn't be a problem.
And the above post is a clear and concise explanatory summation of the original point. *whew*
Quote from: riiga on April 06, 2015, 06:58:57 AM
Are automatic/dynamic signals really that uncommon in the US?
Fully actuated signals, where the controller has the authority to vary the length of a phase based on demand, are as far as I know quite rare in the US. And basically impossible to do at any intersection where the walk signal is automatic rather than only when requested by pushbutton. Semi-actuated signals, where phases that aren't needed can be skipped, are more common, but still hardly universal. Lots of places haven't spent the money on installing the necessary equipment either because they don't have it or haven't seen fit to. New York City's traffic signals are mostly still on simple timers and will change with or without cross traffic.
Nonetheless, even with actuation, it's silly to keep signals running when there are very few cars on the road. In addition to the aforementioned problem of triggering for one lousy right turning car, you also will have signals that keep cycling because one of the detector loops is broken and safe failure means the light keeps changing so as to not strand anyone there. Any and all signals ought to be set to flash at any times when traffic counts are below the threshold of what warrants their existence.
As for bikes, yes, "Idaho stop" is a sensible policy. Of course, most stop signs out there really ought to be yield signs anyway.
Quote from: Duke87 on April 08, 2015, 12:46:08 AM
Quote from: riiga on April 06, 2015, 06:58:57 AM
Are automatic/dynamic signals really that uncommon in the US?
Fully actuated signals, where the controller has the authority to vary the length of a phase based on demand, are as far as I know quite rare in the US. And basically impossible to do at any intersection where the walk signal is automatic rather than only when requested by pushbutton. Semi-actuated signals, where phases that aren't needed can be skipped, are more common, but still hardly universal. Lots of places haven't spent the money on installing the necessary equipment either because they don't have it or haven't seen fit to. New York City's traffic signals are mostly still on simple timers and will change with or without cross traffic.
There's a difference between "fully actuated" and "dynamic". The former means that sensors at an intersection control the operation of a single signal based on vehicles entering an intersection, while the latter uses an interconnected network of sensors to change cycle lengths throughout a network based on network demand.
Fully actuated signals are quite common, especially as municipalities upgrade their signals. In Upstate New York outside of cities, the ability for fully-actuated operation is the norm, even in the suburbs.
Semi-actuated is when at least one phase always operates on a timer.
Dynamic installations, however, are rare due to their cost.
Quote from: Duke87 on April 08, 2015, 12:46:08 AM
Fully actuated signals, where the controller has the authority to vary the length of a phase based on demand, are as far as I know quite rare in the US. And basically impossible to do at any intersection where the walk signal is automatic rather than only when requested by pushbutton. Semi-actuated signals, where phases that aren't needed can be skipped, are more common, but still hardly universal. Lots of places haven't spent the money on installing the necessary equipment either because they don't have it or haven't seen fit to. New York City's traffic signals are mostly still on simple timers and will change with or without cross traffic.
A signal can be adaptively controlled with automatic walks. The problem with automatic walks is the required vehicle phase time may be less than the required pedestrian time, leading to inefficient operations at the intersection. An adaptive signal is handcuffed by a lot of settings baked into the controller...it can't violate the minimum green time, yellow, all red, ECOs, and ped times (among others). By having pushbuttons, the adaptive signal doesn't get handcuffed as badly.
Quote from: swbrotha100 on April 05, 2015, 06:38:03 PM
You need to drive in Tucson more. Tucson does things differently than most cities, in that it's a rarity to have a protective left turn signal anywhere in the city limits. There are any intersections where there are dual left turn lanes that have permissive/protected left turns 24/7.
In my recent trips to Tucson, I've seen very few drivers creeping into the intersection during the green ball phase compared to ten years ago, suggesting the drivers nowadays are more inclined to wait for the arrow. Have you noticed this too?
Quote from: roadiejay on April 09, 2015, 07:40:54 AM
Quote from: swbrotha100 on April 05, 2015, 06:38:03 PM
You need to drive in Tucson more. Tucson does things differently than most cities, in that it's a rarity to have a protective left turn signal anywhere in the city limits. There are any intersections where there are dual left turn lanes that have permissive/protected left turns 24/7.
In my recent trips to Tucson, I've seen very few drivers creeping into the intersection during the green ball phase compared to ten years ago, suggesting the drivers nowadays are more inclined to wait for the arrow. Have you noticed this too?
Could be poor education. Many people believe that being in the intersection while it is red, regardless of the signal color when they entered, is illegal.
I was taught in driver's ed to enter the intersection on both an FYA and a green ball when turning left. But other people, like my sister and mom, don't do it.
Quote from: jakeroot on April 09, 2015, 12:44:05 PM
Could be poor education. Many people believe that being in the intersection while it is red, regardless of the signal color when they entered, is illegal.
I was taught in driver's ed to enter the intersection on both an FYA and a green ball when turning left. But other people, like my sister and mom, don't do it.
FYA? Is that "flashing yellow arrow"? I tried reading about it on Wikipedia but am still not the wiser about it.
Entering an intersection for left turn (or any direction here) is allowed only on green. Does the US allow entering on yellow? Or left turns on red? :crazy:
Left turns on red are allowed in most states... as long as it's from a one-way street to another one-way street :spin:
Quote from: riiga on April 09, 2015, 01:34:32 PM
FYA? Is that "flashing yellow arrow"? I tried reading about it on Wikipedia but am still not the wiser about it.
yes
Quote from: riiga on April 09, 2015, 01:34:32 PM
Quote from: jakeroot on April 09, 2015, 12:44:05 PM
Could be poor education. Many people believe that being in the intersection while it is red, regardless of the signal color when they entered, is illegal.
I was taught in driver's ed to enter the intersection on both an FYA and a green ball when turning left. But other people, like my sister and mom, don't do it.
FYA? Is that "flashing yellow arrow"? I tried reading about it on Wikipedia but am still not the wiser about it.
Entering an intersection for left turn (or any direction here) is allowed only on green. Does the US allow entering on yellow? Or left turns on red? :crazy:
Flashing yellow arrows or lights are for caution: You may enter the intersection while exercising caution. In regards to the FYA, you may proceed to turn when safe to do so.
Don't confuse it with a steady yellow light, which indicates the signal is going to turn red. You can still enter on a yellow if you're too close to the intersection to stop safely. However, you're not supposed to hit the gas and speed up to get into the intersection prior to the light turning red!
Quote from: riiga on April 09, 2015, 01:34:32 PM
Quote from: jakeroot on April 09, 2015, 12:44:05 PM
Could be poor education. Many people believe that being in the intersection while it is red, regardless of the signal color when they entered, is illegal.
I was taught in driver's ed to enter the intersection on both an FYA and a green ball when turning left. But other people, like my sister and mom, don't do it.
FYA? Is that "flashing yellow arrow"? I tried reading about it on Wikipedia but am still not the wiser about it.
Entering an intersection for left turn (or any direction here) is allowed only on green. Does the US allow entering on yellow? Or left turns on red? :crazy:
Depends on the state.
In Illinois, as long as you enter on yellow, you can proceed through the intersection. If you are waiting for a permissive left turn (be it a green ball or a flashing yellow arrow), you pull into the intersection and wait. Even if the signal turns red, you are permitted to wait until all oncoming traffic clears (including the red light runners) before completing your turn. Left turn on red is permitted only from a one-way to a one-way in Illinois.
Michigan is similar to Illinois; however, left turns on red are allowed from two-way to one-way streets, including freeway entrance ramps.
Quote from: roadiejay on April 09, 2015, 07:40:54 AM
Quote from: swbrotha100 on April 05, 2015, 06:38:03 PM
You need to drive in Tucson more. Tucson does things differently than most cities, in that it's a rarity to have a protective left turn signal anywhere in the city limits. There are any intersections where there are dual left turn lanes that have permissive/protected left turns 24/7.
In my recent trips to Tucson, I've seen very few drivers creeping into the intersection during the green ball phase compared to ten years ago, suggesting the drivers nowadays are more inclined to wait for the arrow. Have you noticed this too?
I honestly don't know. With most left turn signals being lagging left, I'm guessing some drivers would just sit behind the stop line and trip the sensors to get a green arrow.
I see. I would guess the rules for standard green, yellow and red are the same throughout the world, apart from right turns on red. The flashing yellow arrow was interesting though. So it's like a yield sign, while flashing red is a full stop? Is there flashing green?
Quote from: riiga on April 09, 2015, 01:51:42 PM
I see. I would guess the rules for standard green, yellow and red are the same throughout the world, apart from right turns on red. The flashing yellow arrow was interesting though. So it's like a yield sign, while flashing red is a full stop? Is there flashing green?
Not supposed to be one in the USA, though that are a few rare instances of them. But they are around in Canada, for either meaning the turning movement is protected or it is a signalized pedestrian crossing.
The best two solutions I can thing of, and both come from Michigan...
1) Flashing Red on the Protect Left signal. Stop wait for a clear spot in traffic, then go. Do no enter the intersection.
2) Michigan Lefts. Eliminate left turns at certain intersections, and force U-Turns.
Quote from: Brandon on April 09, 2015, 01:42:25 PM
Quote from: riiga on April 09, 2015, 01:34:32 PM
Or left turns on red? :crazy:
Michigan is similar to Illinois; however, left turns on red are allowed from two-way to one-way streets, including freeway entrance ramps.
As does Washington. Funny thing is, there is no restriction on the number of lanes or style of signal (i.e. arrow or ball). So you can have a triple left onto an on-ramp and technically you can proceed when it's clear. I've never encountered a triple-left onto a freeway on-ramp personally, but I have turned left from a dual left onto the on-ramp on red before. People are a bit confused but no one has ever honked.
Quote from: TEG24601 on April 09, 2015, 02:23:17 PM
1) Flashing Red on the Protect Left signal. Stop wait for a clear spot in traffic, then go. Do no enter the intersection.
Presuming this is an alternative to a protected signal, following the topic of this thread, why can't you enter the intersection while the signal is flashing red? You should still be able to enter the intersection and wait till it's clear, kind of like a right on red (you slowly inch out and wait till it's clear).
Quote from: TEG24601 on April 09, 2015, 02:23:17 PM
The best two solutions I can thing of, and both come from Michigan...
1) Flashing Red on the Protect Left signal. Stop wait for a clear spot in traffic, then go. Do no enter the intersection.
In theory, yes. In practice...
More like if clear, just fucking go. If not, wait for it to be clear, then just fucking go. And yes, everyone enters the intersection on them.
Quote from: jakeroot on April 09, 2015, 12:44:05 PM
Could be poor education. Many people believe that being in the intersection while it is red, regardless of the signal color when they entered, is illegal.
Not sure if it's the case now or not, but once upon a time in Kentucky, it was illegal to be in intersection when the light turned red, regardless of what color it was when you entered. There was language to that effect in the state police-issued student driver manual that I received when I took my learner's permit test.
Popo lie.
Quote from: NE2 on April 09, 2015, 09:59:53 PM
Popo lie.
Not necessarily. Louisiana has the same law, IIRC. Meanwhile, an Illinois State Trooper said that even when a red light camera is present, you can sit in the intersection all damn day until it clears to make your left turn without a camera ticket as you will have entered on green.
Does the presence of a "Yield on (FYA)" or "Yield on (green ball)" sign imply that one should wait behind the stop line for traffic to clear, or is waiting within the intersection still good? I still haven't figured out if the sign changes anything.
Quote from: dfwmapper on April 10, 2015, 03:43:21 AM
Does the presence of a "Yield on (FYA)" or "Yield on (green ball)" sign imply that one should wait behind the stop line for traffic to clear, or is waiting within the intersection still good? I still haven't figured out if the sign changes anything.
Whether a sign is there or not, I still think it boils down to the given that one is in as to whether it's legal to enter the intersection while waiting to make a left turn. The signage is merely there to remind the driver of what they should already know (certainly true for the green ball sign, the FYA sign might be helpful since it's a relatively new signal display and not all drivers are familiar with it).
Quote from: dfwmapper on April 10, 2015, 03:43:21 AM
Does the presence of a "Yield on (FYA)" or "Yield on (green ball)" sign imply that one should wait behind the stop line for traffic to clear, or is waiting within the intersection still good? I still haven't figured out if the sign changes anything.
You should always pull into the intersection.
Quote from: riiga on April 07, 2015, 07:02:01 AM
Quote from: Scott5114 on April 06, 2015, 08:39:22 PM
Problem with these is that during low traffic periods, you often have one car coming in the green direction, a car pulls up to the red light and it cycles to stop the first car. Even more frustrating when the second car is turning right and could have just gone after the first car passed. We have an expressway in Norman configured like this and it's annoying to have to come to a complete stop from 50 mph so one random person can turn right.
If the lights are set to flash, it eliminates unnecessary stops.
You could have a right turn signal. Or a slip lane with yield signs. Or priority/far away detectors for the expressway.
You could, but all of these cost money (and therefore are unlikely to happen in the current US political climate). Switching to flash mode is a cheap software change.
I agree just switching them to flash mode and obtaining the software is cheaper than making physical modifications.
Quote from: kkt on April 02, 2015, 02:00:25 PM
I'm more bothered by the lack of protected left turn arrows at intersections that need them. Traffic is so heavy there's no chance to turn left during the green phase, so people wanting to turn run the yellow and collide with oncoming traffic also running the yellow.
I was just thinking about that.
I'm grateful every time I *DO* get an intersection with a protected left arrow, in SF. The places without them you get ~1 car through per cycle (2 if someone's feeling dangerous)
Quote from: texaskdog on April 02, 2015, 11:25:07 AMI hate the intersections that have the left arrow AND the traffic going straight. It turns red and the other direction does the same.
What's wrong with simultaneous straight and left-turn traffic in the same direction?
Quote from: hbelkins on April 02, 2015, 01:16:22 PM
Sometimes it seems like protected left turns are installed at random. You'll go through three or four intersections with permitted/protected (doghouses) or FYA's, then all of a sudden you hit one with a protected left. I've started to figure out that sight distance issues are probably the reason most protected lefts are installed amongst a sequence of doghouses or FYAs.
There are two of those protected lefts in Ludington, MI (US-10/Meyers Rd and US-10/Brye Rd). Both intersections are home to a big box store (Walmart at Meyers Rd and Meijer at Brye Rd). The US-10/US-31 SB on ramp, US-10/PM Highway, and US-10/Jevaby Rd intersections are FYA. I go through all of those every day on my way to/from work. At least I don't have to turn left at one of those protected left intersections.
Quote from: jeffandnicole on April 10, 2015, 06:25:06 AM
Quote from: dfwmapper on April 10, 2015, 03:43:21 AM
Does the presence of a "Yield on (FYA)" or "Yield on (green ball)" sign imply that one should wait behind the stop line for traffic to clear, or is waiting within the intersection still good? I still haven't figured out if the sign changes anything.
You should always pull into the intersection.
Not necessarily, but generally a good rule.
If opposing traffic is heavy, I pull into the intersection only if there is a car waiting behind me. My logic is that if I pull beyond the stop line and there is no car behind me, I'm most likely out of the vehicle detection zone--if the signal is set to trigger a lagging protected left if turning traffic is still present at the end of the phase, the signal controller won't know I'm still waiting if I've pulled out beyond the detection zone.
Quote from: roadfro on April 18, 2015, 04:20:39 PM
If opposing traffic is heavy, I pull into the intersection only if there is a car waiting behind me. My logic is that if I pull beyond the stop line and there is no car behind me, I'm most likely out of the vehicle detection zone--if the signal is set to trigger a lagging protected left if turning traffic is still present at the end of the phase, the signal controller won't know I'm still waiting if I've pulled out beyond the detection zone.
Unless I'm mistaken, it shouldn't matter. If the signal skips the lagging turn phase because it doesn't sense anyone, you can still go once oncoming traffic has cleared.
Without reading the whole thread, Texas has started turning those turn lanes into Flashing Yellow Lights to yeild to oncoming traffic or to take your turn without waiting the whole time. Only protected green if its at the start of the light cycle and there are enough cars to trip the switch.
Quote from: jakeroot on April 18, 2015, 04:24:46 PM
Quote from: roadfro on April 18, 2015, 04:20:39 PM
If opposing traffic is heavy, I pull into the intersection only if there is a car waiting behind me. My logic is that if I pull beyond the stop line and there is no car behind me, I'm most likely out of the vehicle detection zone--if the signal is set to trigger a lagging protected left if turning traffic is still present at the end of the phase, the signal controller won't know I'm still waiting if I've pulled out beyond the detection zone.
Unless I'm mistaken, it shouldn't matter. If the signal skips the lagging turn phase because it doesn't sense anyone, you can still go once oncoming traffic has cleared.
This is where the yellow trap was born.
If the opposing direction gets a lagging turn phase, your direction gets the red light. In the meantime, the opposing direction still has a green. Many people mistakenly think that once their light has turned red, the opposing direction's light turned red as well, and will make a turn in front of full-speed traffic.
They've started to install flashing yellow left arrows at some lower-volume intersections in Savannah. Based on the driving skills of most residents and tourists, it will soon be known as "T-bone City".
Personally, I like it; but I've already seen some close calls at an intersection near work.
Quote from: jeffandnicole on April 18, 2015, 06:04:23 PM
This is where the yellow trap was born.
If the opposing direction gets a lagging turn phase, your direction gets the red light. In the meantime, the opposing direction still has a green. Many people mistakenly think that once their light has turned red, the opposing direction's light turned red as well, and will make a turn in front of full-speed traffic.
Generally not a good idea to turn in front of traffic regardless. Drivers shouldn't rely on whether they think the other side is also red or not but by what traffic is doing. Even if the other side is red, someone could run the light - especially important as the vast majority of red light violations occur within the first second of the light turning red.
Saint Louis has a gaggle of these. The worst is Kingshighway and Lindell.
Quote from: vdeane on April 18, 2015, 08:24:02 PM
Quote from: jeffandnicole on April 18, 2015, 06:04:23 PM
This is where the yellow trap was born.
If the opposing direction gets a lagging turn phase, your direction gets the red light. In the meantime, the opposing direction still has a green. Many people mistakenly think that once their light has turned red, the opposing direction's light turned red as well, and will make a turn in front of full-speed traffic.
Generally not a good idea to turn in front of traffic regardless. Drivers shouldn't rely on whether they think the other side is also red or not but by what traffic is doing. Even if the other side is red, someone could run the light - especially important as the vast majority of red light violations occur within the first second of the light turning red.
I don't turn when the light turns yellow. I turn when traffic has stopped. If my light turns red, and oncoming traffic doesn't stop, my instinct tells me to look in my mirror to see if their light is green. If it is, I wait until it isn't and then complete the turn. I still legally entered the intersection on green, it just got kind of awkward for a second.
Quote from: jakeroot on April 19, 2015, 02:29:08 AM
Quote from: vdeane on April 18, 2015, 08:24:02 PM
Quote from: jeffandnicole on April 18, 2015, 06:04:23 PM
This is where the yellow trap was born.
If the opposing direction gets a lagging turn phase, your direction gets the red light. In the meantime, the opposing direction still has a green. Many people mistakenly think that once their light has turned red, the opposing direction's light turned red as well, and will make a turn in front of full-speed traffic.
Generally not a good idea to turn in front of traffic regardless. Drivers shouldn't rely on whether they think the other side is also red or not but by what traffic is doing. Even if the other side is red, someone could run the light - especially important as the vast majority of red light violations occur within the first second of the light turning red.
I don't turn when the light turns yellow. I turn when traffic has stopped. If my light turns red, and oncoming traffic doesn't stop, my instinct tells me to look in my mirror to see if their light is green. If it is, I wait until it isn't and then complete the turn. I still legally entered the intersection on green, it just got kind of awkward for a second.
You should do that regardless, since traffic doesn't always stop on red.
Yellow traps are still poor traffic design.
Here in Georgia, I've sat at intersections with dual left-turn lanes during the wee hours of the morning without the traffic signal even detecting me there. It'd skip the left-turn cycles altogether! And this is with dual lane sensors, which required me to back up about 20 feet and position my truck diagonally across both left-turn lanes in order to jog both sensors and give the hint that somebody's there. When somebody is forced to break the law in order to even go anywhere when there's no traffic, whether it's a failure to stay in one lane or just running a red light, then there's a big problem.
Quote from: Gnutella on April 26, 2015, 06:27:22 AM
Here in Georgia, I've sat at intersections with dual left-turn lanes during the wee hours of the morning without the traffic signal even detecting me there. It'd skip the left-turn cycles altogether! And this is with dual lane sensors, which required me to back up about 20 feet and position my truck diagonally across both left-turn lanes in order to jog both sensors and give the hint that somebody's there. When somebody is forced to break the law in order to even go anywhere when there's no traffic, whether it's a failure to stay in one lane or just running a red light, then there's a big problem.
What type of detection was out there when you got skipped? It's well documented that video detection technology has trouble detecting vehicles in low-light conditions. The Indiana Department of Transportation has enacted a moratorium on video detection due to its substandard performance.
QuoteContact: James Sturdevant, Traffic Systems Engineer, INDOT Operations Support
E-mail: jsturdevant@indot.state.in.us Phone: 317-232-5073.
"INDOT has experience with a wide variety of non-invasive detection technologies. We have found that the only detection technology as accurate and reliable as an induction loop is an induction loop.....
INDOT has enacted a moratorium on the use of video detection due to substandard performance. Rain, snow, fog, wet pavement, headlight glare, sunrise/sunset, wind, lighting changes, shadows, and occlusion from adjacent and crosslanes can all cause detection errors. Use only where induction loops are not practical."
Pierce County (where I live) and WSDOT both use video detection. So far, it's only failed me once. A couple weeks ago, similar to above, I was sitting in a dual left turn lane waiting to do a U-turn. Light was sitting red. Three different cars showed up opposite me (to turn towards what would be my right) and each time, it tripped the through light and gave them a green arrow. I, on the other hand, never got a thing. I eventually just went. Yes, it was dark out. And yes, I'm thinking that's what was responsible for my issue. There's a gas station on the opposite side of the intersection from where I was sitting, and I think the ambient light from the station made the opposite side's turn lanes easier to see for the camera.
The traffic cameras sense a change in contrast in a particularly defined zone on the screen, so it's not just being able to "see" a vehicle or better ambient lighting making detection better. Even if the car is black and sitting on black pavement, the headlights at night should be enough to trip the detection.
That said, there are issues with some detection software and some vendors are better than others... I've never had any issue at video detection signals anywhere in Nevada or California.
Quote from: roadfro on April 26, 2015, 04:13:50 PM
The traffic cameras sense a change in contrast in a particularly defined zone on the screen, so it's not just being able to "see" a vehicle or better ambient lighting making detection better. Even if the car is black and sitting on black pavement, the headlights at night should be enough to trip the detection.
That said, there are issues with some detection software and some vendors are better than others... I've never had any issue at video detection signals anywhere in Nevada or California.
A number of studies spanning the past 20 years have demonstrated performance issues with video detection technology (whether it be missed calls, false calls, stuck on calls, or dropped calls). Here's an abstract of a study comparing the "illumination and wind effects on video detection performance at signalized intersections" :
QuoteThe detection performance of video detection systems at intersections, from three major manufacturers, was evaluated using a side-by-side installation and large datasets. The performance at three stop bar detection zones under two illumination conditions is presented: day with no shadows (cloudy days) and night. In addition, these two conditions and day time with shadows (sunny mornings) are also evaluated under windy conditions. Four measures of performance were used to quantify the errors in the detection: false calls, missed calls, stuck-on calls, and dropped calls. Activation and deactivation times of the detection zones were used to automate the initial calculation of errors, while video images from the intersection were used for their manual verification. Night time results showed an average decrease in false calls for the left-most lane (from about 14% to9%), but an increase for the middle lane (from 1.5% to 23%) and thru-right lane (from 0.8% to 13%). Vehicle headlights reflecting on adjacent zones and the view angle of the cameras were important factors in false calls. Missed calls in night time increased only for one system in one lane (from 0.2% to 26%). Wind increased false calls, mostly in sunny morning conditions (long shadows) between 12% and 17% on average, and reduced stuck-on calls due to the camera oscillation movement. Missed calls increased in day time only, from 0.9% to 2.4%, but it was not possible to identify the exact cause for this increase after a visual inspection of the videos.
There are major swings in accuracy with video detection systems depending on the weather and illumination conditions present. These are inherent problems that have plagued video detection systems from day one. Manufacturers have had 20+ years to improve the video detection systems with limited success. INDOT was so dissatisfied with the operational performance that they placed a moratorium on video detection at signalized intersections. Are the vendors in Indiana really that much worse than the vendors in Vegas and California?
OT: Is there any detection system that can detect cyclists? I would assume, between the in-ground plate and the camera, the latter would have a higher success rate.
Quote from: jakeroot on April 26, 2015, 05:42:15 PM
OT: Is there any detection system that can detect cyclists? I would assume, between the in-ground plate and the camera, the latter would have a higher success rate.
I've been successfully detected by both, but I don't think I've tried a camera at night.
Quote from: NE2 on April 26, 2015, 05:43:26 PM
Quote from: jakeroot on April 26, 2015, 05:42:15 PM
OT: Is there any detection system that can detect cyclists? I would assume, between the in-ground plate and the camera, the latter would have a higher success rate.
I've been successfully detected by both, but I don't think I've tried a camera at night.
Bet you haven't tried the metal detectors NYSDOT loved in the late 90s-early 2000s. Unless you're directly over the square (which is less than 1 ft^2 and, by this point, surrounded by a pothole making it dangerous for everyone who can't straddle it), you won't get detected. Flipping nightmare on a bike as you won't ever get detected. At least they moved back to induction loops and started using radar and infrared detectors, but a bunch still remain in the field.
There is a double right turn that I use frequently that does not allow RTOR. Video detection is used at this intersection. I often use this intersection around 5 am, so it isn't uncommon for me being the only vehicle intending on turning right. I almost always want to use the left right turn lane, since I need to use the left lane once I make my right turn. One morning, however, I used the right lane, since I wanted to make a right turn after the intersection to visit a convenience store. I found out the hard way that video detection doesn't work as designed in the right lane. I waited over 5 minutes and never got a green light (normal wait is 2 minutes maximum). I was getting frustrated and was about to turn right, after looking all over for a cop who might be watching nearby. Just then another vehicle comes along and stops in the left right turn lane and the signal almost immediately tripped. I then figured out why I never got a green light. Ever since then, I've made it a point to use the left lane, even if I want to patronize the aforementioned convenience store. I will just turn into the left lane and make a quick lane change into the right lane after completing my turn.
Here's an example of Forward Looking Infrared (FLIR) detection. This was a demonstration video posted by FLIR traffic.
Quote
FLIR Thermals help monitor an intersection for incidents as well as optimize the flow of traffic by offering superior vehicle detection! For more information, email us at flirtraffic@gmail.com.
There is a stuck on call observed at the very start of the video (top-right video, left turn lane). That's not superior vehicle detection when you can spot a fault within the first second of the video. I'm a bit surprised the company would think this is a good demonstration video to post onto youtube.
Quote from: tradephoric on April 27, 2015, 11:31:49 PM
Here's an example of Forward Looking Infrared (FLIR) detection. This was a demonstration video posted by FLIR traffic.
Quote
FLIR Thermals help monitor an intersection for incidents as well as optimize the flow of traffic by offering superior vehicle detection! For more information, email us at flirtraffic@gmail.com.
There is a stuck on call observed at the very start of the video (top-right video, left turn lane). That's not superior vehicle detection when you can spot a fault within the first second of the video. I'm a bit surprised the company would think this is a good demonstration video to post onto youtube.
Was the video aimed at other traffic engineers or the general public? I assume the former. But more to the point, what the hell is a "stuck on call"?
Quote from: jakeroot link=topic=15187.msg2060980#msg2060980
Was the video aimed at other traffic engineers or the general public? I assume the former. But more to the point, what the hell is a "stuck on call"?
A "stuck-on call" is when detection remains active even after vehicles depart from the detection zone. From my experience, FLIR cameras experience a lot of random stuck-on calls.
Stuck-on calls can be problematic for a few reasons.
1. A stuck-on call can unnecessarily cause a phase to run when a vehicle is no longer on the detection zone.
2. For adaptive signals, a stuck-on call can lead to inaccurate split-voting. A minor side-street may receive the lions share of the green time and squeeze the main phase if a side-street detector is sticking on (the controller thinks a vehicle is sitting on the side-street the entire phase indicating very heavy traffic, when in fact no vehicle is there).
Quote from: roadfro on April 26, 2015, 04:13:50 PM
The traffic cameras sense a change in contrast in a particularly defined zone on the screen, so it's not just being able to "see" a vehicle or better ambient lighting making detection better. Even if the car is black and sitting on black pavement, the headlights at night should be enough to trip the detection.
You are basing your opinions on logic. Unfortunately, the performance of video detection can be illogical. Sure, in theory video detection should work great... it doesn't though.
Quote from: tradephoric on April 29, 2015, 01:27:30 PM
You are basing your opinions on logic. Unfortunately, the performance of video detection can be illogical. Sure, in theory video detection should work great... it doesn't though.
I think you're basing your opinions on too few signals. As I said before, most of the signals near where I live are operated via video detection, and I have not noticed any major issues (other than once many moons ago, and even then, the issue was that it just didn't notice me).
On the other hand, cycling is now a big deal and I'm not entirely convinced in-ground plates are capable of detecting cyclists. In places like Seattle, cycling is a major form of transportation, and they now have to run red lights just to get through signalized intersections. Obviously, ignoring signals is undesirable (to say the least). Can video detection detect cyclists? I don't know. But I think the chances are higher for them than the in-ground plates.
I am basing my opinions on facts. Here is a summary of just some of the research done analyzing the accuracy of video detection. The overwhelming theme is that video detection is not as accurate as inductive loops. That's a fact.
A report from MacCarley (1998) compared the performance of the Vantage Video Traffic Detection System in a wide variety of weather and illumination conditions. The report concluded that under ideal or near ideal traffic, camera configuration, and illumination conditions, the ability to properly detect a vehicle was adequate. It noted, however, that even under optimal conditions false calls were common. The average presence detection accuracy over all data sets was 80.9% with false detection errors of 8.3%.
The Illinois Center for Transportation (2009) tested 3 different VDS systems under a wide variety of illumination conditions. During sunny morning conditions, false calls increased for all 3 systems when compared to the base "cloudy noon" condition: Autoscope increased from 3.5% to 11.2%, Peek from 7% to 14.4%, and Iteris from 5.7% to 20.7%. Additional trends were seen during other lighting conditions with false calls increasing during dawn for all three VDS (up to 23%), and increased false calls were observed at night due to the reflection of headlights on the pavement.
A report by the Federal Highway Administration (2006) analyzed Iteris video detection along a 21-mile stretch of Virginia State Route 7. The report found that that VDS consistently over-counts traffic volumes, consistently missed left-turn phase demands, had frequent occlusion issues along side-street detection, and experienced significant data errors due to glare in sunrise and sunset conditions. As part of the recommendations, it was suggested that the cameras along the route be repositioned to shoot from the near-side of the intersection (looking nearly straight down onto the detection zone) as opposed to shooting across from the far-side of the intersection.
A technical study by Rhodes (2005) found that VDS-based detectors statistically produce a higher number of false detections and a higher number of missed detections than inductive loops. The report cites that lighting is the most common condition for causing video detection errors, especially during transitional periods at sunrise and sunset. The effects of vehicle occlusion can lead to either missed detections (vehicle blocking another vehicle from being detected) or false detections (vehicle placing a call on adjacent lane when no vehicle present).
Quote from: jakeroot on April 29, 2015, 01:40:22 PM
Can video detection detect cyclists? I don't know. But I think the chances are higher for them than the in-ground plates.
Why not just use induction loops? Or is that the same as in-ground plates? They're used at pretty much every intersection I've encountered here, and work for bikes too.
Quote from: riiga on April 29, 2015, 02:23:00 PM
Quote from: jakeroot on April 29, 2015, 01:40:22 PM
Can video detection detect cyclists? I don't know. But I think the chances are higher for them than the in-ground plates.
Why not just use induction loops? Or is that the same as in-ground plates? They're used at pretty much every intersection I've encountered here, and work for bikes too.
Standard induction loops often don't detect motorcycles or bicyclists. Some municipalities install a more sensitive loops on a marked spot. Making the roadway induction loops more sensitive could post problems for false-positives triggering the light.
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fwww.fhwa.dot.gov%2Fpublications%2Fpublicroads%2F08may%2Fimages%2Fgib10.jpg&hash=0897caf56fd5e23697be5f4f955e86c5b8c45c67)
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fupload.wikimedia.org%2Fwikipedia%2Fcommons%2Fthumb%2F8%2F8c%2FInductance_detectors.jpg%2F450px-Inductance_detectors.jpg&hash=2e2ae7fad55e049ebd10db0ede90eff9e699bfcc)
The inaccuracy of video detection is well documented. If a 40-ton semi doesn't get detected by video detection what makes you think a 20 lbs bicycle will? Admittedly, inductive loops can have difficulty detecting bicyclists but so can video detection.
EDIT: Just to be clear, it's not the weight of the vehicles that matter in the above sentence. If a big honking semi doesn't get detected by the camera then it's not looking good for the bicycle which has a much smaller footprint.
Quote from: roadfro on April 26, 2015, 04:13:50 PM
I've never had any issue at video detection signals anywhere in Nevada or California.
Have you ever been to a video detection signal anywhere in Nevada or California? :hmmm:
The City of Norman uses video detection almost exclusively, and I rarely have problems with them. I did have a recently-installed signal appear to fail to detect me recently, but I rarely pass through that intersection and I'm not sure if was actually a failure with the signal or if there's wonky timing programming to blame.
The intersection I have the most problems with is an ODOT-administered signal that uses induction loops. I think the loops were damaged or obscured by recent repaving. Either that or they have some horrendous lag time programmed in. I usually have to sit at the intersection and creep forward a few times before the signal cycles, usually at least a full minute after I've been sitting there.
One thing that I've had success with at video detection signals is flashing my brights for a moment. If the signal is not detecting me, the sudden spike in brightness is often enough to get its attention.
Quote from: tradephoric on April 29, 2015, 10:55:24 PM
Quote from: roadfro on April 26, 2015, 04:13:50 PM
I've never had any issue at video detection signals anywhere in Nevada or California.
Have you ever been to a video detection signal anywhere in Nevada or California? :hmmm:
I'm from Las Vegas and live in Reno...so yeah, I've been through more than a couple video detection signals in Nevada... Video detection has been widely utilized in new signal construction throughout Nevada for the last decade or more.
The rate of new signals in Northern Nevada utilizing video detection has dropped in recent years, but there's still plenty around. I can't say with certainty whether this decline has been due to performance issues (NDOT was doing a study a few years ago out of UNR analyzing effectiveness of various video vendors equipment in multiple light/weather conditions) or to reconstruction (virtually all new or reconstructed signals in Reno/Sparks in recent years have accompanied pavement [re-]construction, when it's easy to put in loops).
However, all the jurisdictions in the Vegas area are still very much on board with video detection. I can only think of one new signal in the past 5-ish years that isn't using video (Las Vegas Blvd at Harmon Ave, where the intersection is so wide and skewed that typical camera positioning would likely be ineffective). Most newer installations have the detection camera mounted along the mast arm on a riser pole (between the left turn and through signal heads), which I assume is done to help alleviate some of the occlusion issues. Most cameras, particularly those facing east/west, also usually have a longer visor to help reduce issues with sun glare during sunrise/sunset.
Quote from: jakeroot on April 29, 2015, 01:40:22 PMI think you're basing your opinions on too few signals. As I said before, most of the signals near where I live are operated via video detection, and I have not noticed any major issues (other than once many moons ago, and even then, the issue was that it just didn't notice me).
Aren't you basing your opinions on too few signals? For one, faulty detection can be easily masked by tying down the signal. Many signals have minimum recalls and will cycle a phase regardless of detection. In addition, a vehicle that is missed by video detection may still get serviced due to the detection of surrounding vehicles (a vehicle waiting on EB side-street who is getting missed may still get a green because the vehicle on WB side-street is being detected). You can't base your opinions on the accuracy of video detection simply because you "didn't notice any major issues" while driving through the intersection. I'm citing statistically significant studies detailing the performance issues with video detection . I'm the last person that should be accused of providing anecdotal evidence and basing my opinions on "too few signals" in this thread.
Quote from: roadfro on May 02, 2015, 05:02:43 PMHowever, all the jurisdictions in the Vegas area are still very much on board with video detection. I can only think of one new signal in the past 5-ish years that isn't using video (Las Vegas Blvd at Harmon Ave, where the intersection is so wide and skewed that typical camera positioning would likely be ineffective). Most newer installations have the detection camera mounted along the mast arm on a riser pole (between the left turn and through signal heads), which I assume is done to help alleviate some of the occlusion issues. Most cameras, particularly those facing east/west, also usually have a longer visor to help reduce issues with sun glare during sunrise/sunset.
QuoteA report by the Federal Highway Administration (2006) analyzed Iteris video detection along a 21-mile stretch of Virginia State Route 7. The report found that that VDS consistently over-counts traffic volumes, consistently missed left-turn phase demands, had frequent occlusion issues along side-street detection, and experienced significant data errors due to glare in sunrise and sunset conditions. As part of the recommendations, it was suggested that the cameras along the route be repositioned to shoot from the near-side of the intersection (looking nearly straight down onto the detection zone) as opposed to shooting across from the far-side of the intersection.
It's important to note that some agencies do shoot from the near-side of the intersection, with the camera looking nearly straight down onto the detection zone. Sun glare and inaccurate detection during sunrise/sunset conditions is not rectified by shooting straight down. Shooting straight down works great in a cloudy noon conditions, but fail under sunrise/sunset conditions (just like cameras that shoot across the intersection that are pointed more towards the horizon). I have a feeling that simply extending the visor isn't going to solve the sun glare issue either.
Quote from: roadfro on May 02, 2015, 05:02:43 PM
The rate of new signals in Northern Nevada utilizing video detection has dropped in recent years, but there's still plenty around. I can't say with certainty whether this decline has been due to performance issues (NDOT was doing a study a few years ago out of UNR analyzing effectiveness of various video vendors equipment in multiple light/weather conditions) or to reconstruction (virtually all new or reconstructed signals in Reno/Sparks in recent years have accompanied pavement [re-]construction, when it's easy to put in loops).
I'd be interested in the results of UNR's study.