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Old 09-30-2015, 09:30 PM
 
436 posts, read 513,295 times
Reputation: 164

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There are basically three kinds of left turn displays:

- Permissive - Left turns are allowed through gaps in traffic on a circular green or a flashing yellow arrow.

- Protected/Permissive - Left turns are protected with a green arrow or are allowed through gaps in traffic on a circular green or a flashing yellow arrow.

- Exclusively Protected - Left turns are protected with a green arrow.

One rule used to determine whether or not to add left turn signals is whether or not traffic backs up in the left turn lane 4 or more hours each weekday.

Whether or not a permissive turn will be allowed depends on several factors. The following are usually reasons why a permissive turn is not allowed.

- Speed limit above 45 mph
- 3 or more oncoming straight-ahead lanes
- 2 or more left turn lanes
- Sight distance problems
- Unusual geometry of left turn
- Receiving lane of left turn is not visible from the stop line
- Left turns from opposite directions cross each other's paths
- Split phasing used (each leg on the street gets its own green)
- Other unusual signal sequence used
- 5 or more approaches to the intersection
- Offset intersection
- High pedestrian volume
- Accident history of permissive turns
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Old 09-30-2015, 10:35 PM
 
Location: Westminster/Huntington Beach, CA
1,780 posts, read 1,242,179 times
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In parts of suburban Southern California the lights used to be mostly yield lights. So you would just have a green circular light but could turn left as long as you yielded to pedestrians and oncoming traffic. These are all being replaced one by one by left turn on arrow only.

It may seem frustrating as a driver, but the amount of pedestrians killed and accidents that occurred just on my neighborhood intersection alone really outweighs that slight frustration.
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Old 10-01-2015, 01:39 AM
 
33 posts, read 25,334 times
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In CT, you can generally turn left on a regular/circular green right with the understanding that you yield to oncoming traffic and pedestrians. Sometimes there will be a green arrow first to allow a few cars to turn left with right of way and then it switches to a regular green light where left turning vehicles must yield.

When I lived in WA state, you could turn left on red onto a one way street or on-ramp. Never got used to that.
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Old 10-01-2015, 08:23 AM
 
Location: Albuquerque, NM
706 posts, read 512,838 times
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Chaotic! Some here in ABQ have them, some don't. A lot of them are activated by weight sensors here, some by video-monitoring software. Some are controlled by city buses, some by computer buses, some by both. Some, strangely enough, are asymmetric, and only have an arrow in one direction.

In the middle of the night when few cars are out, they usually are ignored, as some arrows will stay red indefinitely until cross-traffic arrives and triggers a signal cycle (or till about 6).
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Old 10-01-2015, 09:33 AM
 
Location: The Springs
1,770 posts, read 2,136,059 times
Reputation: 1850
Quote:
Originally Posted by bus man View Post
We have three types of signalized left turns around here:

1. Solid green. This one is treated like a yield sign. A left turn is allowed after yielding the right of way to oncoming traffic; it is not necessary to stop beforehand, if the way is clear.

2. Green arrow. Left-turning traffic has the right of way; oncoming traffic has a red light.

3. Flashing red arrow. This one is pretty new (around here at least) but is becoming increasingly popular. A flashing red arrow would be treated like a stop sign; one may make a left turn only after coming to a full stop (regardless of whether the way is clear), and then going once any oncoming traffic is clear.
In addition, we are installing flashing yellow arrows, indicating it is clear to turn when YOU have the right-of-way.
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Old 10-01-2015, 10:09 PM
 
Location: Albuquerque, NM
706 posts, read 512,838 times
Reputation: 407
Quote:
Originally Posted by Kar54 View Post
In addition, we are installing flashing yellow arrows, indicating it is clear to turn when YOU have the right-of-way.
I forgot about those. I heard in the news recently that we will be getting flashing yellows as well.
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Old 10-02-2015, 10:56 AM
 
Location: Brooklyn, New York
3,734 posts, read 3,846,240 times
Reputation: 3560
Quote:
Originally Posted by prospectheightsresident View Post
In NYC you can pretty much turn left on a regular green, though there are more than a few left-turn only arrows and banned left-turns completely.
NYC is also the only city in the United States where it is illegal to turn right on red. NYPD makes nice revenue from all those visitors who decide to bring their car into the city...
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Old 07-04-2017, 11:14 AM
 
436 posts, read 513,295 times
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Which kind of signal you have usually depends on the design and traffic characteristics of the intersection and the age of the signal.

1. Whether or not permissive turns are allowed through gaps in traffic usually depends on several factors:

- Are there three or more lanes of straight-ahead oncoming traffic?
- Is the speed limit higher than 40 mph?
- Are pedestrians a concern?
- Are there left turn lanes?
- Is there a double-lane left turn?
- Is the left turn path unusual?
- Is there a sight-distance problem?
- Do the paths of left turns from opposite direction cross each other's paths?
- Do permissive turns have a bad accident history?
- Does the intersection have an unusual geometry or more than 4 legs?

2. Which kind of permissive turn is allowed depends on several factors:

- Is the signal sequence dangerous if circular greens is used?
- Can the left turns be restricted to leading turns (left goes before oncoming straight)?
- Does the progression plan need a lead-lag sequence?
- Are there exclusive left turn lanes? How long are they?
- Is the left turn lane some distance away from the straight-ahead lanes or at an angle?
- Do the paths of left turns from opposite direction cross each other's paths?
- Can the controller be set up to prevent any lagging left turn sequence?
- Is there money to replace the signal controller and conflict monitor for flashing yellow arrows?
- Do permissive turns have a yellow trap accident history?
- Does the government allow flashing yellow arrows?

3. Signals that do not allow permissive left turns have a three-arrow signal with steady red, yellow, and green arrows.

4. Signals that allow permissive left turns without flashing yellow arrows have a five-section two-arrow signal with steady yellow, and green arrows and steady circular red, yellow, and green indications.

5. Signals that allow permissive left turns with flashing yellow arrows have a four-arrow signal with steady red arrow, steady yellow arrow, flashing yellow arrow, and steady green arrow.

6. Yellow trap must be prevented or signed: ONCOMING TRAFFIC MAY HAVE EXTENDED GREEN.

7. No circular green is allowed over or directly in front of a left turn lane.

8. Flashing yellow arrows prevent yellow trap when properly implemented.

9. Flashing yellow arrows require an exclusive left turn lane.

10. Flashing yellow arrows have been allowed in different states for different lengths of time. Maryland requires a flashing red arrow instead of a flashing yellow arrow. West Virginia never passed a law allowing flashing yellow arrows.
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Old 07-04-2017, 02:48 PM
 
Location: Minneapolis, MN
6,053 posts, read 3,377,056 times
Reputation: 7690
I live in North Texas too, though I grew up in South Florida and I think green arrows are more common but damn they don't last a second. I don't like intersections that don't have green arrows. I was stuck trying to turn left in Minneapolis and it was a yield left only and it took forever for me to go because the cars coming and coming.

BTW Denton, Texas has the WORST traffic lights I've ever seen. Worst. Goddamn terrible.
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Old 07-04-2017, 08:53 PM
 
Location: Wonderland
44,651 posts, read 36,106,549 times
Reputation: 63182
Northeast Texas here:

1. Green arrow - Absolute right of way
2. Green but no arrow - yield but can turn if no oncoming traffic
3. Flashing yellow arrow - replacing the green but no arrow in a lot of areas - means the same thing and really, really confuses some people!
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