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Old July 11th, 2010, 11:22 AM   #381
WalkTheWorld
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Originally Posted by Fuzzy Llama View Post

Nah, they are good if you place them right. I like what Switzerland and Liechtenstein does with them - they put the lights under the directional signs, so it's very clear which light stands for which direction:
Same here. Standard lights, vertical, lights on direction panels: horizontal.

Like this



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Old July 11th, 2010, 01:20 PM   #382
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Albuquerque traffic lights with Red Light Camera:

image hosted on flickr
What are those two extra lights on the median traffic light and that sign "Left turn YIELD on green?".
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Old July 11th, 2010, 04:12 PM   #383
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What are those two extra lights on the median traffic light and that sign "Left turn YIELD on green?".
"Left turn yield on green" means that if you want to turn left and you have a full green rather than an arrow, you can do so, but you need to yield to oncoming traffic. I'd guess that the two extra lights are a green left arrow and a yellow left arrow. Since what usually follows a yellow is a red, that sign has the effect of telling people "even though we just went through the yellow phase, you can still turn. Just yield first."

First time I encountered such an assembly the "Left turn yield on green" sign really was informative to me for just the reason I described.
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Old July 12th, 2010, 12:01 PM   #384
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Some observations:

1. In Israel all left turns are protected. This is simply fantastic and I miss them allot. In Washington USA some are not (added left turn yield on green sign). It can sometimes be difficult to cross and since you are not allowed to stop on a pedestrian crossing you are sometime caught IN THE MIDDLE of the interaction until ongoing traffic has passed and even if the light turns red you must still turn left.. talk about upside down... Thankfully this is only the case on local roads anything with 2/3+ lanes or sees heavy traffic usually has a protected left turn light. The protected lights are in the shape of a left arrow and obviously there is no yield on green sign.

WA yield on left:
[IMG]http://t1.************/images?q=tbn:Bmsxq54dkh86wM:http://www.wpclipart.com/travel/US_Road_Signs/regulation/reg_2/left_turn_yield_on_green.png[/IMG]

WA protected left:
[IMG]http://t3.************/images?q=tbn:7uh3vrBpQyRrGM:http://driversed.com/courseware/images/greenArrow.jpg[/IMG]

2. In Israel most of W Europe and here in the US on many roads where crossing traffic has off hours (industrial areas, schools, offices etc) the light stays green all the time for the main road unless a car arrives at the intersection. This is fantastic for speeding up many intersections on the weekends or for preventing you from stopping at red lights on empty roads.

3. Here in the US there are no blinking green lights and you can easily look at a mirror for a split second and look up to see the light on yellow..

4. Most lights are placed at the end of the intersection, with an added side light for the right turn lane.

5. On large highways/freeways here in WA before you enter it you may have a "ramp meter" a light in order to slow down traffic joining the freeway. It is only turned on when there is congestion. The HOV lane (buses, taxis, cars with 2+ passengers) can bypass the light.



6. The body of most lights in WA are black Some lights that do not have direct sunlight have a yellow boarder around them to make them stand out other lights that get sunlight have no boarder or a black one.

Sorry for the lack of pics ill take some over the next few days

Last edited by Dr.Scope; July 12th, 2010 at 12:35 PM.
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Old July 12th, 2010, 12:28 PM   #385
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Originally Posted by Penn's Woods View Post
"Left turn yield on green" means that if you want to turn left and you have a full green rather than an arrow, you can do so, but you need to yield to oncoming traffic. I'd guess that the two extra lights are a green left arrow and a yellow left arrow. Since what usually follows a yellow is a red, that sign has the effect of telling people "even though we just went through the yellow phase, you can still turn. Just yield first."

First time I encountered such an assembly the "Left turn yield on green" sign really was informative to me for just the reason I described.
Correct me if I am wrong (we don't have such lights in WA)
During 1 light cycle there may be 2 times when you can turn left. On a very congested road like the one in the picture you might first have a PROTECTED left turn (green arrow) and then have a "Left turn yield on green" when the light has the second green light (rounded green light).
In WA an arrow shaped green/yellow light always means that the turn is Protected.
There may also be a red arrow shaped light that means that there is NO right on red in the direction of the arrow.

Not sure if it is the same down in NM.

Last edited by Dr.Scope; July 12th, 2010 at 12:47 PM.
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Old July 12th, 2010, 02:29 PM   #386
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Yes those turn left turns when you have to yield to traffic are called permissive. The highway admin officially introduced a new style of light last year to fix two problems. One was accidents when using this style the light changes from the yellow ball to red. The biggest problem really was phasing in some places the change from the yellow to red would happen while the opposing traffic light would stay green. People assumed the opposing traffic is getting a yellow and continue to turn leading to "yellow trap". There is also the issue of standardization States vary in way they handled permissive lefts Michigan uses a flashing red ball other some variations of flashing red/yellow ball/arrows.

States had been allowed to experiment with for the last few years with a four light flashing yellow signal now it officially part of the highway standards. The "yellow trap" phasing has been banned the green ball lights are still permitted for use if the left and through shared lane the light. But states discouraged from using them.


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Old July 12th, 2010, 05:24 PM   #387
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Quote:
Originally Posted by Dr.Scope View Post
Some observations:

1. In Israel all left turns are protected. This is simply fantastic and I miss them allot. In Washington USA some are not (added left turn yield on green sign). It can sometimes be difficult to cross and since you are not allowed to stop on a pedestrian crossing you are sometime caught IN THE MIDDLE of the interaction until ongoing traffic has passed and even if the light turns red you must still turn left.. talk about upside down... Thankfully this is only the case on local roads anything with 2/3+ lanes or sees heavy traffic usually has a protected left turn light. The protected lights are in the shape of a left arrow and obviously there is no yield on green sign.

WA yield on left:
[IMG]http://t1.************/images?q=tbn:Bmsxq54dkh86wM:http://www.wpclipart.com/travel/US_Road_Signs/regulation/reg_2/left_turn_yield_on_green.png[/IMG]

WA protected left:
[IMG]http://t3.************/images?q=tbn:7uh3vrBpQyRrGM:http://driversed.com/courseware/images/greenArrow.jpg[/IMG]
Heh yeah, in Israel all left turns are protected indeed (see the very first post in this thread ), which is a nice feature, although apparently not very efficient.

The non-protected behaviour is actually standard in almost all countries around the world, so I don't understand why the "Left Turn Yield On Green" sign exists. Unless you have a protected light (clearly distinguished by being an arrow), you have to yield. This is not the case in only a handful of countries, Israel being one of them.

By the way - you are lucky in WA then, since it seems that protected lights are still very common, especially on bigger roads. In Toronto almost all left turns are not protected (many lights do have a protected phase, but virtually all lights also have a permissive one). It doesn't matter if a road has 1 lane or 4 lanes (to the same direction) - it most likely has an unprotected left turn.

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Originally Posted by urbanlover View Post


Yes those turn left turns when you have to yield to traffic are called permissive. The highway admin officially introduced a new style of light last year to fix two problems. One was accidents when using this style the light changes from the yellow ball to red. The biggest problem really was phasing in some places the change from the yellow to red would happen while the opposing traffic light would stay green. People assumed the opposing traffic is getting a yellow and continue to turn leading to "yellow trap". There is also the issue of standardization States vary in way they handled permissive lefts Michigan uses a flashing red ball other some variations of flashing red/yellow ball/arrows.
Wow, that's murderous! How can such an intersection be allowed? A permissive left turn where the signals for the oncoming traffic are not synchronized with the signals for through traffic make no sense to me. As I said, in Ontario most left turns are unprotected, but you always complete your turn on yellow/red if you don't get a chance to do it earlier. Though, mind you, people still have to make sure that the oncoming traffic has actually stopped, since many cars pass on yellow (so in practice the turn is almost always completed on red). That's the standard and correct way to perform such a turn here. In theory, in some countries in Europe one cannot see the lights once in the intersection, so it's necessary to ensure that traffic has actually come to a complete stop, but in that case you cannot see the lights at all (sometimes a green arrow appears during the red trap phase, such as in Germany and some other countries).

As for completely protected left turns at all times, like it is done in Israel, I have always been an advocate of them, but after further research into the matter, it seems that those aren't always ideal. In theory, permissive (i.e. yield-on-green) left turns combined with a time-limited protected phase keep traffic flowing more efficiently. Also, at off-peak times it is often possible to make a permissive turn quickly without a protected phase (especially at night). In Israel, most lights require at least 4 separate phases to allow everyone to go straight/turn right and turn left in a protected manner. This reduces the green time per phase, and makes people wait longer for a green light.

The safety argument is also somewhat debatable, since I read somewhere that the completely-protected traffic light design in Israel actually increases accidents at some intersections, because it makes people less mindful of other traffic and encourages jumping yellow/red lights, especially left turn lights. I don't know to what extent it is true. My only complaint is that there are many unprotected lights here in Toronto that should be exclusively protected, due to various combinations of many lanes, high speed limit, and limited visibility (or a combination of all 3, as at a particular intersection around here that I complained about several times on this forum ).
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Old July 12th, 2010, 05:31 PM   #388
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The non-protected behaviour is actually standard in almost all countries around the world, so I don't understand why the "Left Turn Yield On Green" sign exists. Unless you have a protected light (clearly distinguished by being an arrow), you have to yield.
Because what immediately preceded the solid green was a yellow arrow. You wouldn't know this if you came upon the intersection while it's in the solid-green phase, but if you were in the left-turn lane waiting to turn (because there were people ahead of you) you'd have seen that yellow, and your expectation - if this sort of assembly is new to you - is that red will be next, so your instinct after the yellow turns off is to stop. So the yellow arrow disappears, but no red arrow appears and you're thinking, now what? The "Left Turn Yield on Green" tells you it's okay to go, as long as you yield to oncoming trafic. I really did find this helpful the first time I came upon this sort of assembly - I swear I did! :-)
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Old July 12th, 2010, 05:49 PM   #389
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non-protected left turns are dangerous, but require less traffic light phases, thus a higher throughput.

The most dangerous feature is that someone wants to make a left turn, but oversees someone going straight ahead at high speed = big collision.
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Old July 12th, 2010, 05:49 PM   #390
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Old July 12th, 2010, 05:55 PM   #391
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Old July 12th, 2010, 05:55 PM   #392
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I don't see how they're dangerous by default. I mean, there are tons of situations where you have to yield to oncoming traffic anyway. Protected cross-turns should only be used when deemed necessary, as they are less efficient than the conventional arrangement when traffic doesn't justify them.
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Old July 12th, 2010, 05:59 PM   #393
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It's especially dangerous when you have to cross 2 or 3 lanes from the other direction.
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Old July 12th, 2010, 06:05 PM   #394
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It's especially dangerous when you have to cross 2 or 3 lanes from the other direction.
...And yet it's the standard method of turning left on Columbia Pike in Arlington. Most other roads have protected left-turn lanes, but this road has o left turn lanes, which is kinda frustrating since I have to turn left on that road both to go to work and to come home. I know of an alternative route that involves bypassing the normal left turn, and making a right-hand loop to turn left instead, but I've never taken that route.
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Old July 12th, 2010, 06:24 PM   #395
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It's especially dangerous when you have to cross 2 or 3 lanes from the other direction.
...at high speed, around a curve, in a wooded area....

(US 1/Md. 24 southbound at the point where they separate, on the outskirts of Bel Air, Maryland. Traffic wanting to go south on 24 needs to cross 1 northbound. That's the first place I remember seeing this left-turn-yield-on-solid-green thing.)
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Old July 12th, 2010, 06:24 PM   #396
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Because what immediately preceded the solid green was a yellow arrow. You wouldn't know this if you came upon the intersection while it's in the solid-green phase, but if you were in the left-turn lane waiting to turn (because there were people ahead of you) you'd have seen that yellow, and your expectation - if this sort of assembly is new to you - is that red will be next, so your instinct after the yellow turns off is to stop. So the yellow arrow disappears, but no red arrow appears and you're thinking, now what? The "Left Turn Yield on Green" tells you it's okay to go, as long as you yield to oncoming trafic. I really did find this helpful the first time I came upon this sort of assembly - I swear I did! :-)
Heh, fair enough, although the way it works in Toronto, is that first you have a green left arrow together with either a red ball (simultaneous protected left turns) or a green ball (go straight/right + protected left turn). Then after a while, the same arrow turns yellow (so there is no separate yellow arrow - it simply changes colour), after which it disappears.

If the arrow appeared together with a red ball, then after it disappears the red ball remains for a while, and then turns into a green ball, after which one may turn left after yielding. If it appeared together with a green ball, then the arrow simply disappears, after which the protected phase ends and one must now yield. In some places in Ontario there is still a separate yellow arrow (haven't seen those at all in Toronto - I think they're being phased out in the rest of the province, but not sure), but in either case I think it is quite clear what to do without a sign, since the arrow never appears by itself without a red or green solid ball, unless it is an exclusive left turn signal.

I think the reason this confusion exists in the States is because in many jurisdictions there is a separate light above each lane, so you need to have a way to distinguish between a permissive and protected left turn that occurs specifically above the left-turn lane. It's not necessary, but I can see where it can cause confusion.

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...And yet it's the standard method of turning left on Columbia Pike in Arlington. Most other roads have protected left-turn lanes, but this road has o left turn lanes, which is kinda frustrating since I have to turn left on that road both to go to work and to come home.
In the Toronto area there are countless intersections like that. Almost all major streets (that have 2-3, and sometimes 4 lanes in each direction) allow unprotected left turns.
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Old July 12th, 2010, 06:27 PM   #397
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...And yet it's the standard method of turning left on Columbia Pike in Arlington. Most other roads have protected left-turn lanes, but this road has o left turn lanes, which is kinda frustrating since I have to turn left on that road both to go to work and to come home. I know of an alternative route that involves bypassing the normal left turn, and making a right-hand loop to turn left instead, but I've never taken that route.
Jersey jughandles would solve that.
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Old July 12th, 2010, 09:04 PM   #398
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Jersey jughandles would solve that.
There's no room, there are businesses on both sides of the road, plus lots of 4-way intersections. It would be much easier to just add a protected left turn lane.

This is one of two intersections where I have to turn left off Columbia Pike. (It's best to turn labels on there) and this is the other place where I could turn left, although it's substantially farther away.
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Old July 12th, 2010, 09:15 PM   #399
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And about horizontal traffic lights - in my driver's ed class I was taught that horizontal traffic lights always have red on the left. I haven't actually seen any myself but I've seen pictures of them, and this does seem to be the case.
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Old July 12th, 2010, 10:10 PM   #400
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Wow, that's murderous! How can such an intersection be allowed? A permissive left turn where the signals for the oncoming traffic are not synchronized with the signals for through traffic make no sense to me. As I said, in Ontario most left turns are unprotected, but you always complete your turn on yellow/red if you don't get a chance to do it earlier. Though, mind you, people still have to make sure that the oncoming traffic has actually stopped, since many cars pass on yellow (so in practice the turn is almost always completed on red). That's the standard and correct way to perform such a turn here. In theory, in some countries in Europe one cannot see the lights once in the intersection, so it's necessary to ensure that traffic has actually come to a complete stop, but in that case you cannot see the lights at all (sometimes a green arrow appears during the red trap phase, such as in Germany and some other countries).
.
My understanding is that supposed to be more efficient in terms coordinating signals

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