Atlantic Cities: Should Cities Help Drivers Hit Green Lights All the Time? (http://www.theatlanticcities.com/technology/2014/01/should-cities-help-drivers-hit-green-lights-all-time/8214/)
QuoteThere's plenty of "smart" traffic light innovation going around these days. But if you're perpetually stuck in traffic, the smartest light is surely the one that turns green right when you get there. Traffic Light Assist, a product German automaker Audi showcased at the Consumer Electronics Show in Las Vegas earlier this month, comes with the promise that hitting the green light, every time, could one day be a reality.
QuoteCombining data from a city's traffic signal infrastructure and the car itself, Traffic Light Assist shows the driver a countdown clock to green as well as what speed to drive at to make the next green light, all in a dashboard display. Audi claims that by making traffic flow more efficiently, TLA can help cut down on carbon emissions as well.
Every time I've driven in the UK I've wished the US would allow the combined red-yellow cycle that comes on prior to the green light (I know this is used in other countries as well, but I cite the UK because it's the one in which I've driven the most). The American omission of that cycle means that unless you either know the light really well or you watch the signal for the other road (the correct signal head, in many cases), you have no idea when the light is about to turn, and it results in the inevitable delay waiting for people to get moving (especially the mobile-phone users, which is a growing problem that the additional cycle might not solve). When I leave my neighborhood, the stop bar at the light is set over a car length back from the other road. I watch the light for the other road and when it goes yellow, I shift into first gear and start easing off the clutch so the car is already rolling by the time my green arrow comes on. Can't do that at all lights, of course, but it sure would be nice if there were a better way to know when the green is about to come on.
Quote from: 1995hoo on January 30, 2014, 04:40:50 PM
Every time I've driven in the UK I've wished the US would allow the combined red-yellow cycle that comes on prior to the green light (I know this is used in other countries as well, but I cite the UK because it's the one in which I've driven the most).
Finland has this at certain intersections as well, including protected left turns.
Quote from: 1995hoo on January 30, 2014, 04:40:50 PM
The American omission of that cycle means that unless you either know the light really well or you watch the signal for the other road (the correct signal head, in many cases), you have no idea when the light is about to turn, and it results in the inevitable delay waiting for people to get moving (especially the mobile-phone users, which is a growing problem that the additional cycle might not solve). When I leave my neighborhood, the stop bar at the light is set over a car length back from the other road. I watch the light for the other road and when it goes yellow, I shift into first gear and start easing off the clutch so the car is already rolling by the time my green arrow comes on. Can't do that at all lights, of course, but it sure would be nice if there were a better way to know when the green is about to come on.
Only issue I would see with this is pedestrian and bicyclist safety.
In California, where the driving "culture" is to be very good about yielding to pedestrians, this would be a
great idea. In the UK (at least in the part of England around London) drivers are similarly very polite to pedestrians (and as I have stated before, I have not dared to drive in Britain, but I have walked there - a lot - and ridden many submodes of transit).
In many metropolitan areas of the Eastern U.S. (including specifically Washington and Baltimore), I believe it might make for more vehicle crashes involving peds
where the motorist is at fault.
Quote from: 1995hoo on January 30, 2014, 04:40:50 PM
The American omission of that cycle means that unless you either know the light really well or you watch the signal for the other road (the correct signal head, in many cases), you have no idea when the light is about to turn...it sure would be nice if there were a better way to know when the green is about to come on.
Luckily, the combination of ped and vehicle signals at most standard four-way intersections in San Francisco largely accomplish this already.
The cycle goes: Light facing you is green. Ped countdown (facing your direction) goes to zero; vehicle signal immediately turns yellow, then red.
And when the light you're approaching is currently red, in many cases, you can see the ped signal facing the perpendicular direction going from flashing to solid, indicating that the cross street light is turning red and your direction will soon have green.
It has saved me endless frustration trying to beat lights in futility or losing momentum on a red light that's about to change. There are a few lights which are exceptions to the pattern, but you quickly learn which they are.
Don't think they need "smart" signals, just well-timed signals. A well-timed set of signals can also help regulate the speeds along the street.
Here in the Fort Worth area a new toll road is being built from Fort Worth to Cleburne. The highway to southwest Fort Worth is certainly warranted, but extending it to Cleburne seems like a waste of money. SH 174 already connects there. It has a minimum of four lanes, with six through the towns. If they could time the signals so traffic didn't have consecutive red lights so frequently (at least where the signals are close together), they could save a bunch of money on the unneeded highway extension. Of course, now that the toll road is being built, I wouldn't be surprised if they put up more signals and found some way to time them even worse.
Quote from: Brandon on January 30, 2014, 04:56:24 PM
Don't think they need "smart" signals, just well-timed signals. A well-timed set of signals can also help regulate the speeds along the street.
You know, it's funny....if I'm driving on either of the paired one-way streets that carry US-1 through Old Town Alexandria, Virginia, I can hit all the green lights on that section* in succession–
if I exceed the 25-mph speed limit by at least 5 mph (which is not always possible due to traffic, of course). If I go the speed limit, I invariably have to stop for multiple lights. That tells me either the lights are mistimed or the speed limit is set incorrectly.
The "green wave" you can encounter in New York is all too rare elsewhere.
*By "on that section," I mean I may have to stop at red lights on the portions either immediately south of or north of the paired one-way section, but I can make it through the entire one-way portion without stopping. On northbound trips I can't remember the last time I didn't have to stop at the light at Duke Street right as the one-way portion begins.
I just think they need to time it right.
(However, it seems impossible to time it right in both directions.)
Quote from: 1 on January 30, 2014, 08:11:29 PM
I just think they need to time it right.
(However, it seems impossible to time it right in both directions.)
If they were smart, they'd dump the left turn lanes and build more roads like Telegraph Road.
Here's a demonstration video of the technology in action along Telegraph Road.
Quote from: 1995hoo on January 30, 2014, 04:40:50 PM
Every time I've driven in the UK I've wished the US would allow the combined red-yellow cycle that comes on prior to the green light (I know this is used in other countries as well, but I cite the UK because it's the one in which I've driven the most). The American omission of that cycle means that unless you either know the light really well or you watch the signal for the other road (the correct signal head, in many cases), you have no idea when the light is about to turn, and it results in the inevitable delay waiting for people to get moving (especially the mobile-phone users, which is a growing problem that the additional cycle might not solve). When I leave my neighborhood, the stop bar at the light is set over a car length back from the other road. I watch the light for the other road and when it goes yellow, I shift into first gear and start easing off the clutch so the car is already rolling by the time my green arrow comes on. Can't do that at all lights, of course, but it sure would be nice if there were a better way to know when the green is about to come on.
I mentioned this study before, but it compares intersections in Malaysia both before and after the installation of count down signals. The study found that the installation of count down timers had no effect on increasing throughput. That being said, I have seen many clueless drivers completely miss a left-turn phase because they weren't paying attention to the signal. The Malaysia study did find that the use of count down signals dramatically reduced the occurrence of red light runners.
http://www.easts.info/on-line/proceedings_05/1301.pdf
By the way, count down timers can be used at adaptive traffic signals. In order to maintain coordination, the signals along an adaptive corridor must have a known "pulse" point. This pulse point is almost always at the termination of the main-street green. Drivers on the major corridor would know exactly when the signal is going to change from green to red, even if the signals are running adaptive. However, drivers on the side-street wouldn't known when their phase is ending since that phase is usually allowed to gap out early. In addition, drivers waiting at a red light on the major corridor wouldn't know when they are going to get a green until the side-street termination begins (but then the countdown timer could start when the side-street starts running its clearance intervals... so drivers on the main corridor could get roughly a 6 second heads-up that the light is about to change from red to green). I hope that makes sense!
Isnt this the point o fITS corridors to keep traffic moving as much as possible on the major thoroughfares.
I remember how on Madison Ave in Sac County they had synchronized the signals from I-80 to Sunrise Blvd to keep traffic moving. You only usually had to stop about 4-5 times in the 15 signals between the two major intersections.
Quote from: 1995hoo on January 30, 2014, 04:40:50 PM
Every time I've driven in the UK I've wished the US would allow the combined red-yellow cycle that comes on prior to the green light.
Back in the old days here in various parts of the United States, traffic signals used to display that particular overlap you mentioned in your comment. There was also a green/amber overlap, but the meaning was the total opposite. It indicated to a motorist to slow down and come to a full stop, since the red signal indication appeared lit after this overlap terminated.
Of course, times have changed, and, with that said, standards in traffic control have changed as well.
Some towns use traffic signals for slowing traffic. Or in the case of Springfield, MO, as cash cows (for those who remember Red Light Cameras)
Quote from: US71 on February 01, 2014, 07:09:41 AM
Some towns use traffic signals for slowing traffic.
Yup. The speed limit is 35, but if you go 35 you get stopped by the lights at the minor intersections.
Until you realize that if you go 45, you'll beat the light.
So what happened to the traffic calming now?
Quote from: GaryV on February 01, 2014, 07:26:03 AM
Quote from: US71 on February 01, 2014, 07:09:41 AM
Some towns use traffic signals for slowing traffic.
Yup. The speed limit is 35, but if you go 35 you get stopped by the lights at the minor intersections.
Until you realize that if you go 45, you'll beat the light.
So what happened to the traffic calming now?
It's called "the law of unintended consequences". These morons thought that by stopping traffic at the signals they'd calm traffic. Instead, traffic wised up to their game and goes faster to compensate for the poorly timed signalization. It's why we have a lot of speeding between signals in northeast Illinois and a lot of red light running.
Quote from: briantroutman on January 30, 2014, 04:55:33 PM
Quote from: 1995hoo on January 30, 2014, 04:40:50 PM
The American omission of that cycle means that unless you either know the light really well or you watch the signal for the other road (the correct signal head, in many cases), you have no idea when the light is about to turn...it sure would be nice if there were a better way to know when the green is about to come on.
Luckily, the combination of ped and vehicle signals at most standard four-way intersections in San Francisco largely accomplish this already.
The cycle goes: Light facing you is green. Ped countdown (facing your direction) goes to zero; vehicle signal immediately turns yellow, then red.
And when the light you're approaching is currently red, in many cases, you can see the ped signal facing the perpendicular direction going from flashing to solid, indicating that the cross street light is turning red and your direction will soon have green.
It has saved me endless frustration trying to beat lights in futility or losing momentum on a red light that's about to change. There are a few lights which are exceptions to the pattern, but you quickly learn which they are.
That's one thing I liked about driving in the Bay Area. It seemed the countdowns were everywhere and they all went on with the green light whether there were any pedestrians there or not. As I posted before if really tripped me up when I drove into Oregon, and started slowing down way down when the counter reached zero anticipating a red, pissing off a truck driver behind me.
This seems needlessly complicated and needlessly distracting.
I'm going to have to echo the sentiment of "just time the lights better, dummy".
Quote from: 1995hoo on January 30, 2014, 05:12:02 PM
Quote from: Brandon on January 30, 2014, 04:56:24 PM
Don't think they need "smart" signals, just well-timed signals. A well-timed set of signals can also help regulate the speeds along the street.
You know, it's funny....if I'm driving on either of the paired one-way streets that carry US-1 through Old Town Alexandria, Virginia, I can hit all the green lights on that section* in succession–if I exceed the 25-mph speed limit by at least 5 mph (which is not always possible due to traffic, of course). If I go the speed limit, I invariably have to stop for multiple lights. That tells me either the lights are mistimed or the speed limit is set incorrectly.
The "green wave" you can encounter in New York is all too rare elsewhere.
I have noticed this as well - it seems to be more obvious when driving southbound on the Henry Street part of the couplet than it is northbound. Not sure why.
I do know that
severe afternoon peak-period traffic congestion on Henry Street (including gridlocking to the point that the city had to assign traffic control officers at each intersection) went away when the Woodrow Wilson Bridge reconstruction project was complete enough to have both spans between Alexandria and Prince George's County open to traffic.
Quote from: Brandon on February 01, 2014, 08:07:05 AM
It's called "the law of unintended consequences". These morons thought that by stopping traffic at the signals they'd calm traffic. Instead, traffic wised up to their game and goes faster to compensate for the poorly timed signalization. It's why we have a lot of speeding between signals in northeast Illinois and a lot of red light running.
Many (most?) streets in the District of Columbia feature signalized intersections that could (or should) be re-timed. But people that drive those streets regularly know how much over the posted speed limit they have drive to "make" the green phase in signalized intersections.
Quote from: Duke87 on February 01, 2014, 10:49:06 PM
This seems needlessly complicated and needlessly distracting.
I'm going to have to echo the sentiment of "just time the lights better, dummy".
It's easy to say just time the lights better. The problem is most 2-way roads have closely spaced and irregularly spaced traffic signals. These two factors ruin the potential for good 2-way progression. The best ITS system in the world isn't going to fix bad geometrics.
Quote from: cpzilliacus on February 02, 2014, 02:37:58 PM
Quote from: 1995hoo on January 30, 2014, 05:12:02 PM
You know, it's funny....if I'm driving on either of the paired one-way streets that carry US-1 through Old Town Alexandria, Virginia, I can hit all the green lights on that section* in succession–if I exceed the 25-mph speed limit by at least 5 mph (which is not always possible due to traffic, of course). If I go the speed limit, I invariably have to stop for multiple lights. That tells me either the lights are mistimed or the speed limit is set incorrectly.
The "green wave" you can encounter in New York is all too rare elsewhere.
I have noticed this as well - it seems to be more obvious when driving southbound on the Henry Street part of the couplet than it is northbound. Not sure why.
....
That's my experience too, and I don't know why it works out that way either. I do find I'm often able to maintain a slightly higher speed on the southbound trip (why, I don't know) and maybe that contributes to it, as I'll usually be hitting a couple of the lights during the final ten seconds before they change (this based on noticing the pedestrian countdown signals, all of which hit zero right as the light goes yellow). Slowing down even a little bit would thus probably make me hit a red somewhere–usually at King Street or Prince Street, it seems.
Quote from: cpzilliacus on February 02, 2014, 02:40:17 PM
Quote from: Brandon on February 01, 2014, 08:07:05 AM
It's called "the law of unintended consequences". These morons thought that by stopping traffic at the signals they'd calm traffic. Instead, traffic wised up to their game and goes faster to compensate for the poorly timed signalization. It's why we have a lot of speeding between signals in northeast Illinois and a lot of red light running.
Many (most?) streets in the District of Columbia feature signalized intersections that could (or should) be re-timed. But people that drive those streets regularly know how much over the posted speed limit they have drive to "make" the green phase in signalized intersections.
No doubt the District's response would be not to re-time the lights but rather to throw up more speed cameras set to a minimal tolerance.
One of the problems nowadays with trying to hit a series of green lights is the delay you encounter in getting started in the first place. So many people don't pay attention and don't move when the light goes green because they're focused on other things like playing with mobile phones, doing their makeup, digging in the glovebox, etc. This morning was a rare instance where I didn't have to beep the horn to get someone ahead of me to start moving at a green light.
The other thing I've noticed at traffic lights lately doesn't necessarily contribute to getting through a series of lights or not getting through, but it's still darn annoying, especially if you're trying to get into a turn lane. I've noticed people seem to leave way more space than they used to. I find it's not unusual to see full carlength spaces being left open. No doubt some of this comes from people who don't move up when the cars in front of them move; as a manual-shift driver I understand that, although if there were a full carlength I'd roll forward. But I see a lot of people who come to a stop really early and prematurely, leaving a huge gap. I don't understand it. I know 20 years ago or so there was a lot of publicity about carjackings in some places and there were suggestions that people should try to leave some space for an "escape route," but you don't hear much about carjackings these days, and in any event if you're in traffic leaving an "escape route" is futile.
I suppose the huge gaps may well contribute to people not getting through lights when you're in heavy traffic because it results in you being further back on the road than you might otherwise be, such that you wind up stopping before a light rather than getting across the intersection. Last Thursday morning I couldn't make it across an intersection, so I stopped rather than block the box....the obnoxious woman behind me started blowing her horn at me and pointing at the green light. :rolleyes: I half-expected her to try to get around me and cut back in and block the box.
Look at the sizes of the gaps people were leaving here (click to play video). Since there's no dedicated turn lane at the next light, I took advantage of one of the gaps.
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fi31.photobucket.com%2Falbums%2Fc378%2F1995hoo%2FDashcam%2520videos%2Fth_GuyleavestoomuchspaceEBConstitutionat9thIcutintothegap_zpsa9f57515.jpg&hash=e16342b2e9048143f64187136ef3654883ea6bd7) (http://i31.photobucket.com/albums/c378/1995hoo/Dashcam%20videos/GuyleavestoomuchspaceEBConstitutionat9thIcutintothegap_zpsa9f57515.mp4)
Quote from: cpzilliacus on February 02, 2014, 02:37:58 PM
Quote from: 1995hoo on January 30, 2014, 05:12:02 PM
Quote from: Brandon on January 30, 2014, 04:56:24 PM
Don't think they need "smart" signals, just well-timed signals. A well-timed set of signals can also help regulate the speeds along the street.
You know, it's funny....if I'm driving on either of the paired one-way streets that carry US-1 through Old Town Alexandria, Virginia, I can hit all the green lights on that section* in successionif I exceed the 25-mph speed limit by at least 5 mph (which is not always possible due to traffic, of course). If I go the speed limit, I invariably have to stop for multiple lights. That tells me either the lights are mistimed or the speed limit is set incorrectly.
The "green wave" you can encounter in New York is all too rare elsewhere.
I have noticed this as well - it seems to be more obvious when driving southbound on the Henry Street part of the couplet than it is northbound. Not sure why.
I do know that severe afternoon peak-period traffic congestion on Henry Street (including gridlocking to the point that the city had to assign traffic control officers at each intersection) went away when the Woodrow Wilson Bridge reconstruction project was complete enough to have both spans between Alexandria and Prince George's County open to traffic.
This.
It happens often: Widen or improve a highway, and motorists will often change their commute to use that highway. But then the environmentilists, NIMBYs, anti-highway/pro-mass transit crowd pipes up saying that the highway improvement didn't work and already filled up with cars.
While it's partially true, DOTs and others need to point out that alternative routes - which are often residential or really meant for local traffic - are less crowded. Thus, the locals are able to get around better, and the longer-distance traffic is kept on the highway.
And, on the widened highway, the congestion doesn't last as long. Instead of congestion going for 3 hours, maybe it only occurs for 1 hour.
Quote from: 1995hoo on February 03, 2014, 10:29:09 AM
Quote from: cpzilliacus on February 02, 2014, 02:37:58 PM
Quote from: 1995hoo on January 30, 2014, 05:12:02 PM
You know, it's funny....if I'm driving on either of the paired one-way streets that carry US-1 through Old Town Alexandria, Virginia, I can hit all the green lights on that section* in succession–if I exceed the 25-mph speed limit by at least 5 mph (which is not always possible due to traffic, of course). If I go the speed limit, I invariably have to stop for multiple lights. That tells me either the lights are mistimed or the speed limit is set incorrectly.
The "green wave" you can encounter in New York is all too rare elsewhere.
I have noticed this as well - it seems to be more obvious when driving southbound on the Henry Street part of the couplet than it is northbound. Not sure why.
....
That's my experience too, and I don't know why it works out that way either. I do find I'm often able to maintain a slightly higher speed on the southbound trip (why, I don't know) and maybe that contributes to it, as I'll usually be hitting a couple of the lights during the final ten seconds before they change (this based on noticing the pedestrian countdown signals, all of which hit zero right as the light goes yellow). Slowing down even a little bit would thus probably make me hit a red somewhere–usually at King Street or Prince Street, it seems.
The default simulation models in Synchro assume that some drivers are exceeding the speed limit by as much as 15% of the actual link speed. Of course it goes the other way too, where some drivers are only going 85% of the link speed. I would say timing a corridor for 5 mph over the speed limit may help reduce the number of "soft stops" drivers experience. This might help cut down on the number of rear-end accidents.
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fi478.photobucket.com%2Falbums%2Frr144%2Ftradephoric%2FTransportation%2520Pictures%2FRandom%2Fsimtraffic_zps16999e21.jpg&hash=af0bdf1d43e5f759d4790c998f62ebd61470f797) (http://s478.photobucket.com/user/tradephoric/media/Transportation%20Pictures/Random/simtraffic_zps16999e21.jpg.html)
What do you mean by "soft stops"?
It's not a technical term, but to me a "soft stop" is when a driver has to come to a complete (or near complete) stop for only a few moments at a red light. When a corridor is timed for exactly the posted speed limit, the platoon of vehicles coming from an upstream signal can experience these "soft stops" since a percentage of drivers are always going to drive above the posted speed limit and get to the light early.
Quote from: cpzilliacus on February 02, 2014, 02:37:58 PM
Quote from: 1995hoo on January 30, 2014, 05:12:02 PM
Quote from: Brandon on January 30, 2014, 04:56:24 PM
Don't think they need "smart" signals, just well-timed signals. A well-timed set of signals can also help regulate the speeds along the street.
You know, it's funny....if I'm driving on either of the paired one-way streets that carry US-1 through Old Town Alexandria, Virginia, I can hit all the green lights on that section* in succession–if I exceed the 25-mph speed limit by at least 5 mph (which is not always possible due to traffic, of course). If I go the speed limit, I invariably have to stop for multiple lights. That tells me either the lights are mistimed or the speed limit is set incorrectly.
The "green wave" you can encounter in New York is all too rare elsewhere.
I have noticed this as well - it seems to be more obvious when driving southbound on the Henry Street part of the couplet than it is northbound. Not sure why.
I do know that severe afternoon peak-period traffic congestion on Henry Street (including gridlocking to the point that the city had to assign traffic control officers at each intersection) went away when the Woodrow Wilson Bridge reconstruction project was complete enough to have both spans between Alexandria and Prince George's County open to traffic.
This sounds like a situation where they lowered the speed limit but never changed the light timing on the signals.
Quote from: mrsman on February 07, 2014, 02:09:15 PM
Quote from: cpzilliacus on February 02, 2014, 02:37:58 PM
Quote from: 1995hoo on January 30, 2014, 05:12:02 PM
Quote from: Brandon on January 30, 2014, 04:56:24 PM
Don't think they need "smart" signals, just well-timed signals. A well-timed set of signals can also help regulate the speeds along the street.
You know, it's funny....if I'm driving on either of the paired one-way streets that carry US-1 through Old Town Alexandria, Virginia, I can hit all the green lights on that section* in succession–if I exceed the 25-mph speed limit by at least 5 mph (which is not always possible due to traffic, of course). If I go the speed limit, I invariably have to stop for multiple lights. That tells me either the lights are mistimed or the speed limit is set incorrectly.
The "green wave" you can encounter in New York is all too rare elsewhere.
I have noticed this as well - it seems to be more obvious when driving southbound on the Henry Street part of the couplet than it is northbound. Not sure why.
I do know that severe afternoon peak-period traffic congestion on Henry Street (including gridlocking to the point that the city had to assign traffic control officers at each intersection) went away when the Woodrow Wilson Bridge reconstruction project was complete enough to have both spans between Alexandria and Prince George's County open to traffic.
This sounds like a situation where they lowered the speed limit but never changed the light timing on the signals.
Later this year I will have lived in this area for 40 years, and in that time I don't ever remember the speed limit on that road being higher than 25 mph.
Back in the early to mid 70's Philadelphia used to have a system like that on Chestnut and Walnut Streets (PA 3), every two to three blocks you would see a sign mounted on a pole beside the traffic light with a variable speed limit sign, usually set at 35; if you went at that speed when the light changed green you could travel quite a few city blocks before you got stopped at a light (IIRC, usually you got stopped at 60th, 52nd and 44th Streets whether you liked it or not).
I thought it was a quite neat and smart way to keep the traffic moving; alas, that experiment only lasted a couple of years before those signs got removed and the timing was changed back.
Illinois tries to make drivers hit red lights. Its pretty sad.
what we need is more permissive turns, as opposed to outright forbidden ones. California has nearly all of its intersections with turn phases set to forbidden during the non-turn phases, even though there is damn near nobody coming and one could safely squeeze several turning cars through the intersection with a permissive green.
hell, I'd even advocate that red lights should be treated as stop signs. you may go, but yield to everyone. basically, allow right turn on red to be expanded to straight and left on red after stop.
traffic lights where you're stopped for absolutely no one are the worst.
Re-timing a corridor with bad geometry is like putting new tires on a car without an engine... it doesn't fix much. A city needs a good grid layout if they want to keep traffic moving.
Quote from: agentsteel53 on February 19, 2014, 09:12:42 PM
what we need is more permissive turns, as opposed to outright forbidden ones. California has nearly all of its intersections with turn phases set to forbidden during the non-turn phases, even though there is damn near nobody coming and one could safely squeeze several turning cars through the intersection with a permissive green.
hell, I'd even advocate that red lights should be treated as stop signs. you may go, but yield to everyone. basically, allow right turn on red to be expanded to straight and left on red after stop.
traffic lights where you're stopped for absolutely no one are the worst.
This is said a lot, but I think it's worse to have a permissive turn when you really need a protected, such that the left turn lane backs up, since only one or two cars can get through breaks in oncoming traffic on each cycle. There's a few of these in Norman, and I would much rather have a longer nominal wait with a guaranteed chance of going when the light turns green rather than a "here, the light is theoretically green. good luck!" permissive.
That's why I like doghouse signals. The left turning traffic has a guaranteed time to go when the arrow is on, and can go at other times when traffic allows. You get the positives of both and the negatives of neither.
^Other than safety considerations. A permissive-protected left-turn is going to have a higher crash rate than a protected only left-turn.
I don't think we should set traffic policy based on the lowest common denominator.
The negative side of a permissive-protected left turn is that they have higher crash rates than protected-only left turns. You said "That's why I like doghouse signals. You get the positives of both and the negatives of neither."
I like doghouses too, but there are negatives (ie. higher crash rates).
The crash rates are caused mostly by bad driving. As I said, I don't think we should set traffic policy to the lowest common denominator.
The rest of the crash rates are mostly bad engineering. Don't give one side an extended green. Don't make it illegal to be in an intersection with a red signal if you entered on a green or yellow. Stuff like that. I've never had a problem making a left turn at a doghouse signal. I almost always get infuriated at a protected-only turn.
Quote from: vdeane on February 24, 2014, 07:06:16 PM
The crash rates are caused mostly by bad driving. As I said, I don't think we should set traffic policy to the lowest common denominator.
The rest of the crash rates are mostly bad engineering. Don't give one side an extended green. Don't make it illegal to be in an intersection with a red signal if you entered on a green or yellow. Stuff like that. I've never had a problem making a left turn at a doghouse signal. I almost always get infuriated at a protected-only turn.
Um... It's simple fact that permitted left turns lead to more crashes than protected-only left turns. You have no conflicting traffic when it's protected, but you do have conflicts when it's permitted. Conflicts = crashes.
Quote from: Alps on February 25, 2014, 01:11:59 AM
Um... It's simple fact that permitted left turns lead to more crashes than protected-only left turns. You have no conflicting traffic when it's protected, but you do have conflicts when it's permitted. Conflicts = crashes.
you are literally correct. however, come out to California and see the drawbacks of overpermissive left turns. there are intersections where, due to the terrain, you can clearly see that no one is coming for over a mile, and you could drive even the slowest vehicle through safely. to gate these off is just inefficient. certainly there's a tradeoff between "more crashes" and "more people getting through the intersection", and California I think has placed their tradeoff point well into the overcautious.
If someone can't judge whether or not they can safely make a permissive left turn, IMO they shouldn't be driving. Don't dumb down the roads for those of us who can do such things.
^It sounds like you are unwilling to acknowledge that an increased intersection crash rate would be a negative consequence of permissive-lefts. Based on your comments, you are disregarding safety and focused entirely on reducing driver delay. You almost seem to be suggesting that when bad drivers get in an accident, that's somehow a good thing.
Quote from: agentsteel53 on February 25, 2014, 09:16:41 AM
Quote from: Alps on February 25, 2014, 01:11:59 AM
Um... It's simple fact that permitted left turns lead to more crashes than protected-only left turns. You have no conflicting traffic when it's protected, but you do have conflicts when it's permitted. Conflicts = crashes.
you are literally correct. however, come out to California and see the drawbacks of overpermissive left turns. there are intersections where, due to the terrain, you can clearly see that no one is coming for over a mile, and you could drive even the slowest vehicle through safely. to gate these off is just inefficient. certainly there's a tradeoff between "more crashes" and "more people getting through the intersection", and California I think has placed their tradeoff point well into the overcautious.
Exactly! There is a tradeoff. But you have to acknowledge both sides exist in making your determination.
Quote from: tradephoric on February 25, 2014, 03:30:42 PM
^It sounds like you are unwilling to acknowledge that an increased intersection crash rate would be a negative consequence of permissive-lefts. Based on your comments, you are disregarding safety and focused entirely on reducing driver delay. You almost seem to be suggesting that when bad drivers get in an accident, that's somehow a good thing.
I don't think we should delay drivers to subsidize bad driving... IMO we could accomplish a goal of reducing crashes much better by increasing licensing standards. There are a some intersections where high traffic might warrant protected-only lefts, but they're few and far between in my experience. I have to go though one every time I drive from Rome to Rochester (thankfully I can bypass that infernal light on the reverse trip). Every single time I'm stuck waiting at the intersection for two minutes to make the turn while there is hardly any oncoming traffic.
Quote from: vdeane on February 25, 2014, 10:00:57 PM
Every single time I'm stuck waiting at the intersection for two minutes to make the turn while there is hardly any oncoming traffic.
Do you really always get there in the same part of the cycle?
Quote from: Alps on February 25, 2014, 07:39:00 PM
Quote from: agentsteel53 on February 25, 2014, 09:16:41 AM
Quote from: Alps on February 25, 2014, 01:11:59 AM
Um... It's simple fact that permitted left turns lead to more crashes than protected-only left turns. You have no conflicting traffic when it's protected, but you do have conflicts when it's permitted. Conflicts = crashes.
you are literally correct. however, come out to California and see the drawbacks of overpermissive left turns. there are intersections where, due to the terrain, you can clearly see that no one is coming for over a mile, and you could drive even the slowest vehicle through safely. to gate these off is just inefficient. certainly there's a tradeoff between "more crashes" and "more people getting through the intersection", and California I think has placed their tradeoff point well into the overcautious.
Exactly! There is a tradeoff. But you have to acknowledge both sides exist in making your determination.
Adding to the complexity here is when traffic volumes go up enough, a permissive left actually has less throughput than a protected. A protected cycle will usually go for long enough to clear the left turn bay. But on a traffic-choked street, you might get the minimum–the one car that inches out into the intersection as it waits, then makes the turn as the signal goes yellow and oncoming traffic comes to a stop. The rest of the time it's waiting for a gap that never comes.
Quote from: vdeane on February 25, 2014, 10:00:57 PM
Quote from: tradephoric on February 25, 2014, 03:30:42 PM
^It sounds like you are unwilling to acknowledge that an increased intersection crash rate would be a negative consequence of permissive-lefts. Based on your comments, you are disregarding safety and focused entirely on reducing driver delay. You almost seem to be suggesting that when bad drivers get in an accident, that's somehow a good thing.
I don't think we should delay drivers to subsidize bad driving... IMO we could accomplish a goal of reducing crashes much better by increasing licensing standards.
There's no question on the driver's test for hubris, haste, or self-importance, which are the real issue. At least aroud here, it's usually a game of chicken more than a judgement of clear right of way. Someone turns left and decides oncoming traffic will just have to slow/stop rather than hit them. I know people who intentionally don't slow down when confronted with this -- the game of chicken often has more than one willing actor involved.
Quote from: 1 on February 25, 2014, 10:11:55 PM
Quote from: vdeane on February 25, 2014, 10:00:57 PM
Every single time I'm stuck waiting at the intersection for two minutes to make the turn while there is hardly any oncoming traffic.
Do you really always get there in the same part of the cycle?
Good question; I'm really not sure. It does vary a little, but if I hit the light on a Saturday or Sunday as I usually do, I almost always have to wait a while. It's better during the week. It's a three phase signal, with two short phases for traffic turning left to/from the Thruway (right turning traffic has ramps - if you added a jughandle, it would be an at-grade trumpet) and one very long green for through traffic on Super 365. My only guess is that Turning Stone has something to do with it.
Quote from: Pete from Boston on February 26, 2014, 12:15:46 PM
Quote from: vdeane on February 25, 2014, 10:00:57 PM
Quote from: tradephoric on February 25, 2014, 03:30:42 PM
^It sounds like you are unwilling to acknowledge that an increased intersection crash rate would be a negative consequence of permissive-lefts. Based on your comments, you are disregarding safety and focused entirely on reducing driver delay. You almost seem to be suggesting that when bad drivers get in an accident, that's somehow a good thing.
I don't think we should delay drivers to subsidize bad driving... IMO we could accomplish a goal of reducing crashes much better by increasing licensing standards.
There's no question on the driver's test for hubris, haste, or self-importance, which are the real issue. At least aroud here, it's usually a game of chicken more than a judgement of clear right of way. Someone turns left and decides oncoming traffic will just have to slow/stop rather than hit them. I know people who intentionally don't slow down when confronted with this -- the game of chicken often has more than one willing actor involved.
The game of chicken should be outlawed and drivers caught playing it should face very stiff penalties. I have no problem with getting rid of the "make your own ROW" culture that plagues many areas.
It's also criminal that the road test stays on quiet residential streets. It should test all manner of driving situations, not only residential driving, but also downtown streets, suburban business districts, freeways, and rural highways. Maybe make driver's ed mandatory too. I was always taught that one should never assume that traffic on side streets will stop, that turning traffic will yield, or that drivers will actually turn if their turn signal is on. I may not be aggressive enough in some instances because of this (generally, I won't move in any situation requiring a yield unless I can do so without affecting any other traffic at all), but at least my driving record is better than most people's.
Quote from: Scott5114 on February 26, 2014, 07:16:46 AM
Adding to the complexity here is when traffic volumes go up enough, a permissive left actually has less throughput than a protected. A protected cycle will usually go for long enough to clear the left turn bay. But on a traffic-choked street, you might get the minimum–the one car that inches out into the intersection as it waits, then makes the turn as the signal goes yellow and oncoming traffic comes to a stop. The rest of the time it's waiting for a gap that never comes.
I think we've got a bug in our terminology here. we don't have a word for "has a protected phase, and is permissive - as opposed to forbidden - at other times".
that's what I'm advocating for, and that's the tradeoff that Steve is mentioning. it's not "permissive vs protected", it's "permissive vs forbidden".
Exactly. Permissive-only on high traffic roads is even more annoying than protected-only when there's a gap in traffic.
Quote from: vdeane on February 26, 2014, 02:02:55 PM
Exactly. Permissive-only on high traffic roads is even more annoying than protected-only when there's a gap in traffic.
If left turns are needed, then the signals should be protective-permissive, IMHO. I'd prefer to avoid having left turns off major roads though, instead using things such as the Michigan Left or the jughandle.
then again, if you want to talk about the worst left turns in the country, try San Francisco.
there are certain intersections where lefts are forbidden. the only way to make a left is to make either a right-left-left, or a left-right-left, starting one block prior. in either case, that final left turn will be onto the arterial that was originally forbidden: except now you have no protection at all, and no guarantees of ever seeing a break in traffic.
why not make three right turns? go look up Park Presidio southbound at Fulton. I'd provide a link except Google Maps decided to self-annihilate, going from a useful tool, to an instant browser crash.
Quote from: agentsteel53 on February 26, 2014, 03:06:29 PM
why not make three right turns? go look up Park Presidio southbound at Fulton.
That's a little weird. If I were planning it in advance, I'd go Balboa-14th-Cabrillo-10th. Other somewhat reasonable possibilities would be Crossover (coming out on Fulton 11.5 blocks west) or Cabrillo-18th (coming out 4.5 blocks west).
Or I'd turn right onto Fulton's north-side sidewalk and cross Fulton at the crosswalk :bigass:
does 10th have a signal with Fulton?
that said, "planning it in advance" is not universally a feasible proposition. sometimes... you just get there and that's just that.
Quote from: agentsteel53 on February 26, 2014, 08:39:27 PM
does 10th have a signal with Fulton?
Yes, I checked.
Ideally there'd be signs posted, like at jughandles in New Jersey (even where city streets are used (http://maps.google.com/maps?ll=40.922998,-74.110519&spn=0.006574,0.014173&gl=us&t=m&z=17&layer=c&cbll=40.922968,-74.110636&panoid=5leE0zsiPCM2dSBHUE1EoQ&cbp=12,87.57,,1,2.78).)
Quote from: vdeane on February 26, 2014, 01:38:22 PM
Quote from: 1 on February 25, 2014, 10:11:55 PM
Quote from: vdeane on February 25, 2014, 10:00:57 PM
Every single time I'm stuck waiting at the intersection for two minutes to make the turn while there is hardly any oncoming traffic.
Do you really always get there in the same part of the cycle?
Good question; I'm really not sure. It does vary a little, but if I hit the light on a Saturday or Sunday as I usually do, I almost always have to wait a while. It's better during the week. It's a three phase signal, with two short phases for traffic turning left to/from the Thruway (right turning traffic has ramps - if you added a jughandle, it would be an at-grade trumpet) and one very long green for through traffic on Super 365. My only guess is that Turning Stone has something to do with it.
Quote from: Pete from Boston on February 26, 2014, 12:15:46 PM
Quote from: vdeane on February 25, 2014, 10:00:57 PM
Quote from: tradephoric on February 25, 2014, 03:30:42 PM
^It sounds like you are unwilling to acknowledge that an increased intersection crash rate would be a negative consequence of permissive-lefts. Based on your comments, you are disregarding safety and focused entirely on reducing driver delay. You almost seem to be suggesting that when bad drivers get in an accident, that's somehow a good thing.
I don't think we should delay drivers to subsidize bad driving... IMO we could accomplish a goal of reducing crashes much better by increasing licensing standards.
There's no question on the driver's test for hubris, haste, or self-importance, which are the real issue. At least aroud here, it's usually a game of chicken more than a judgement of clear right of way. Someone turns left and decides oncoming traffic will just have to slow/stop rather than hit them. I know people who intentionally don't slow down when confronted with this -- the game of chicken often has more than one willing actor involved.
The game of chicken should be outlawed and drivers caught playing it should face very stiff penalties. I have no problem with getting rid of the "make your own ROW" culture that plagues many areas.
Is there an economist in the house? Where is the margin of disutility of enforcement? In other words, at what point is the cost of ensuring compliance too great for society to accept given the results?
Since you take aim at the cultural issue, the culture of "make your own ROW" here seems to stem from the usual issues of volume of actors in a fluid system that makes transgression with impunity common.
In other words, as the kids say, they won't catch everyone, and they can't flunk the whole class.
The bigger issue seems to be a general cultural disregard for rules. Granted, the Brattons and Giulianis of the world can, over decades, nudge a society into marginally better behavior, but not without costs and ethical decisions that not everyone is ok with.
Anyway, this is a lot to bring into looking at something like jumping out in front of traffic to make a left, but I live in one of those areas "plagued," as you put it, with that wild-west belief that if you follow every rule you'll never get anywhere. So far there hasn't been enough will or societal capital so far to penalize that motivation.
Quote from: Pete from Boston on February 26, 2014, 10:02:23 PM
Anyway, this is a lot to bring into looking at something like jumping out in front of traffic to make a left, but I live in one of those areas "plagued," as you put it, with that wild-west belief that if you follow every rule you'll never get anywhere. So far there hasn't been enough will or societal capital so far to penalize that motivation.
Somewhat to your point, a study was done by the Minnesota Department of Transportation that found there was no long term safety benefits for increasing the all-red clearance interval. Drivers may be more willing to run a red light if they know the signal has a long red clearance. Instead of reducing the accident rate, increasing the red clearance may just increase the probability that a driver will run a red light (at least long-term).
Driver's regulate themselves to a point.
QuoteThe use of a red clearance interval is optional, and there is no consensus on its application or duration. Recent research has indicated that the use of a red clearance interval showed some benefit to the reduction of red-light-running violations. In these studies, there was a significant reduction in right-angle crashes after implementing a red clearance interval. Other research suggests that this reduction may only be temporary. A comprehensive study of long-term effects for the Minnesota Department of Transportation ()11, indicated short-term reductions in crash rates were achieved (approximately one year after the implementation), but long-term reductions were not observed, which implies that there may not be safety benefits associated with increased red clearance intervals.
http://ops.fhwa.dot.gov/publications/fhwahop08024/chapter5.htm
That's interesting. I'm sure it's been discussed in these forums that there's a movement that asserts that the safest traffic regulation is self-policing and most signals should be removed. I have a dim view of the likely results, but it's an intriguing idea.
Quote from: Pete from Boston on February 27, 2014, 07:22:06 AM
That's interesting. I'm sure it's been discussed in these forums that there's a movement that asserts that the safest traffic regulation is self-policing and most signals should be removed. I have a dim view of the likely results, but it's an intriguing idea.
I feel like the photos I've seen of "insanely heavy traffic" in places like India and Cambodia is due to this very experiment being run.
Quote from: Pete from Boston on February 27, 2014, 07:22:06 AM
That's interesting. I'm sure it's been discussed in these forums that there's a movement that asserts that the safest traffic regulation is self-policing and most signals should be removed. I have a dim view of the likely results, but it's an intriguing idea.
That works well in small groups when everyone is achieving the same goal, especially when there's good communication, or everyone knows what their requirements are to reach that same goal.
In a large, undefined group, which the potential population is every living person, which includes people without licenses, not of age, and can't understand signs, languages, symbols, etc, Self-Policing isn't going to work that well, especially at large intersections. Also especially when people are in their own vehicles, which tends to allow them to be more aggressive or do things they wouldn't normally do.
Quote from: Pete from Boston on February 27, 2014, 07:22:06 AM
That's interesting. I'm sure it's been discussed in these forums that there's a movement that asserts that the safest traffic regulation is self-policing and most signals should be removed. I have a dim view of the likely results, but it's an intriguing idea.
I recall some news articles a few years back about an intersection in the UK where there was a plan to try that. I do not recall ever seeing any follow-up reports about whether it was actually done or, more importantly, how it worked out.
Having seen what happens around here when a power failure knocks out the traffic lights (a majority of drivers brazenly ignore the "all-way stop" law), I rather doubt eliminating all traffic control devices like traffic lights and stop signs would work well.
We could get rid of traffic control devices and employ women to direct traffic:
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fwww.blogcdn.com%2Fwww.gadling.com%2Fmedia%2F2007%2F12%2F5-girl-3.jpg&hash=e3e6c8360d3717362af677b58f3524fb1f230399)
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fassets.vice.com%2Fcontent-images%2Fcontentimage%2Fno-slug%2Fc673c8e64783fd170ffc728b3189e2b9.jpg&hash=e65c7e8382f42f7a9297ec9b0ea1525eb1bb06d4)
Quote from: NE2 on February 26, 2014, 08:51:52 PM
Quote from: agentsteel53 on February 26, 2014, 08:39:27 PM
does 10th have a signal with Fulton?
Yes, I checked.
Ideally there'd be signs posted, like at jughandles in New Jersey (even where city streets are used (http://maps.google.com/maps?ll=40.922998,-74.110519&spn=0.006574,0.014173&gl=us&t=m&z=17&layer=c&cbll=40.922968,-74.110636&panoid=5leE0zsiPCM2dSBHUE1EoQ&cbp=12,87.57,,1,2.78).)
Ideally, there should be signs that dictate how to make this left turn using side streets, but sometimes you just have to know your way around town.
I find it even harder when there are time limited turn restrictions, where it's even less likely that automated directions will help you around. And if you typically pass through the corner at off-hours, you have to learn a new way when you are going by there at rush hour.