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YouTube · by **signal-in-the-box** on Thu Jul 11, 2013 9:12 pm

Along the Seminole Trail section of 29, all of the protected left turn signals (for 29) have shorter yellow light durations than the thru signals do. I don't understand it, don't left turns take longer?
Protected right turn signals have the same yellow time as the thru signals. Left turn signals for the side streets have the same yellow time as the thru signals.

Why do the main street protected left signals have the shortest yellows?

The only video I have is a bad one, and you can only see the red light. But it also shows how much sooner it turns red:
I also added annotations that show the color each signal is showing.
http://www.youtube.com/watch?v=-6GJuOHoBfg

by **coyttl** on Thu Jul 11, 2013 9:26 pm

signal-in-the-box wrote:Along the Seminole Trail section of 29, all of the protected left turn signals (for 29) have shorter yellow light durations than the thru signals do. I don't understand it, don't left turns take longer?

This is common in places where left turns tend to drag through the red clearance, I've seen.

In theory, yes, they take longer, that's why they get the red sooner, so by the time the left turns stop turning left and are clear of the intersection, the thrus are also clear of the intersection.

-Me.

by **2070** on Fri Jul 12, 2013 3:36 pm

Higher speed has a longer yellow......

I have seen the through with 5 second and the turn with 4 second Yellow. :Phil:

by **RunsWithCrouse-Hinds** on Fri Jul 12, 2013 4:40 pm

Here in CO Springs, they seem to do a 3 second yellow for left turns, no matter what the approach is. However, I don't have multiple locations of data to back this up, only from one location so I may be wrong.

by **RYGDWW** on Fri Jul 12, 2013 10:03 pm

Phil's got the answer. Left turns are generally slower than the adjacent through movement. Yellows are based on approach speeds.

by **coyttl** on Sat Jul 13, 2013 10:10 am

RYGDWW wrote:Phil's got the answer. Left turns are generally slower than the adjacent through movement. Yellows are based on approach speeds.

He repeated what I said, and he's got the right answer? Pshaw, thanks. :p

by **RYGDWW** on Sat Jul 13, 2013 10:39 am

coyttl wrote:
RYGDWW wrote:Phil's got the answer. Left turns are generally slower than the adjacent through movement. Yellows are based on approach speeds.

He repeated what I said, and he's got the right answer? Pshaw, thanks. :p

Ah, but Phil said it more concisely!

by **2070** on Sat Jul 13, 2013 11:04 am

The through could have an 8 second yellow and the turn a 3 second yellow. The turn will be red for the rest of the through yellow and through red times.

If they are Phases 2 and 6 for example...... They will turn yellow at the same time because the longer green holds them up together.

They will not cross the barrier until the the last phase times out.

Coordination, Fixed time arteries, Lead/lag arrows and so on.....

The timing explanation is alot bigger than a basement. :rotfl:

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