Marbelite Dog House Protected Left Turn Sequence

An example of a "leader" protected left turn sequence using a restored Marbelite "dog house" type signal.

Category:

Science & Technology

Tags:

• marbelite
• doghouse

[wildhorseguy]

The problem involves arterial streets that have heavy left turn traffic and where the controllers are set to lead / lag in order to prevent cars in the left turn pocket from backing up into and blocking the the thru lanes. In these instances permissive left turns may not clear the pocket so an additional protected left turn interval gets cycled in when the camera sees that the left turn pocket is full. I personally prefer louvered dog houses to the flashing yellow but that's the standard.

[yoshigamer64]

At 0:17, what kind of signal is that? I only saw once.

[wildhorseguy]

It's commonly called a "dog house" for protected / permissive turns. That's why 5sections are necessary. 3M made a bimodal head that had a narrow beam that could be aimed at a specific lane. The colors could be changed in a single section by moving lens filters inside the signal head. Thus a dog house could be replaced with a 3 section in-line signal. MUTCD frowned on "green in the middle" so some 3M heads ended up R-Y-G-(GA/YA) with the bottom arrow section flipping from green to yellow.

[wildhorseguy]

4-section flashing yellow arrow signals are designed to avoid the "Yellow Trap" condition when permissive intervals are used. Safet than dog house signals in those situations. I'll make a video on those once I get a 4-section signal built.

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Painted the AD cluster visors today. Still have some work to do on the doors and have to rewire all the sockets... but coming soon.

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Thanks for watching.

[BLANKNOTING]

"Doghouse Traffic Light Signal"

[riolindasucks]

The leader sequence is better because it clears the intersection of stored left turning vehicles. With the post green left turn more turning vehicles wait for the through green cycle to end and stack up in the turn lane. If you clear those cars first then there are fewer cars that can be hit because they are gone before oncoming traffic can conflict. Most states have left turn leading but Missouri has the post green left arrow in some places.

[DjPyro2010]

You won't get yellow trap if you make both left turns go first (red light with green arrow on both sides) and then allow permissive lefts until the perpendicular traffic gets their turn.

[newsfanatic1000]

No more doghouses, new light with flashing yellow lights will replace soon.

[MRFRUITCAKE98]

some people make left turns when the strait arrow is on

[MRFRUITCAKE98]

my country (england) protected left/right turn has a 3 oulor still but one mor circle at the bottom left/right part of the traffic signal sometimes at the bottom but when it goes green the arrow goes off but your still ok to make those turns cause usually the other road doesent have a progression

[denelson83]

0:19 - Kitty!

[Robotman2268]

they have these everywhere where i live!