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Caution Optional » About

About

SignalTraffic:It’s Just a Phase

In traffic signal terminology, a phase is the state in which a single or series of lights are lit so as to convey a status or directions to the public.  For example, in a 3 phase traffic signal setup, the first phase is green, indicating to drivers that they are allowed to GO.  The second phase is amber which directs the drivers to proceed with CAUTION as the third and final phase is soon to arrive; STOP.

No, the interwebs most definitely does not need another damn blog. But this one is special, because it’s mine. :-)

In this blog I’ll be posting random and not so random thoughts about my traffic signal and sign collection as well as on the collecting community. Please do drop me a comment if you so desire.

Cheers,
Ed T.

10 Responses to “About”

  1. 3liteguy Says:

    Why do you have a picture of yourself next to a vintage NYC Ruleta and didn’t your mother ever tell you to button your coat? :I)

    The wandering minstrel

  2. admin Says:

    That’s actually my great, great grandpa and he was, in that photo, flashing the old lady across the street, so that’s why the coat was unbuttoned. This revelation really put my family’s comments about where I got my mad skills with women into context…

  3. vaughn Says:

    In my experience, your above definition of “phase” is not correct. If in the above paragraph, you were to substitute the word “interval” every place you have “phase”, then it would be correct.

    The most basic controller is two phase. It handles (usually) a main street and a side street. If you want to add a left turn to the main street, then you add a third phase. The standard controller at a big intersection with independend left tuns all around is eight phase. It features a thru phase and a left turn phase for each direction of traffic. It allows any two non-conflicting phases to come up together in various combinations to accomidate traffic.

    My regards to you and your grandfather.

    Best Regards
    Vaughn

  4. admin Says:

    Vaughn, thanks for checking in and your correction on the terminology I used. If I understand you correctly (and the proper definition of phase has vexed me since I first heard it), a phase can be a set of intervals which allows a ‘lane’ (I’m using ‘lane’ to indicate movement either from or towards a new direction of travel, not necessarily a single file) of vehicle movement? So a standard RYG four way would have two phases (North/South traffic and then East/West traffic)? Add a (protected) left turn signal facing North and it’s now a three phase? If so, by adding another left turn signal facing South, would that constitute yet another phase or since it would mirror the North turn signal, would it be included in that phase?

    BTW, gramps sends his props.

    Cheers,
    Ed T.

  5. vaughn Says:

    Ed wrote:

    “…a phase can be a set of intervals which allows a ‘lane’ (I’m using ‘lane’ to indicate movement either from or towards a new direction of travel, not necessarily a single file) of vehicle movement?”

    That is true.

    “So a standard RYG four way would have two phases (North/South traffic and then East/West traffic)?”

    Yes

    “Add a (protected) left turn signal facing North and it’s now a three phase?”

    Yes indeed.

    “If so, by adding another left turn signal facing South, would that constitute yet another phase or since it would mirror the North turn signal, would it be included in that phase?”

    It could be included, but then you could not have a concurrent thru and turn (AKA “overlap”). A typical three phase operation would be; main street left turns, then Main street thrus, then side street thrus.

    I will look at my MUTCD and old IMSA material to see if I can get you a proper, formal, definition of “phase”. Unfortunately, I have that stuff at work so it will be next week.

    Regards;
    Vaughn

  6. admin Says:

    Thanks Vaughn!

  7. Vaughn Says:

    OK, I found an old Second Edition IMSA Traffic Signal Manual (1981) on my shelf here at home that I forgot I had. It has defintions of “Phase” that I think are as clear as mud. But here goes:

    PHASE- A traffic movement of movements receving simultanious right-of-way during one of more intervals.

    Strangely (not so strange if you know the IMSA) there are two different definitions in different sections of the book.

    PHASE- a part of the traffic signal time cycle allocated to any combination of traffic movements receiving right-of-way sinultaniously during one or more intervals.

    INTERVAL- A discrete portion of the signal cycle during which the signal indications remain unchanged.

  8. hfp_rick Says:

    …….My head hurts. :-)

  9. myhobbie Says:

    ?????? otherwise, nice blog….i’ve set the pic as my desktop background ;)

  10. admin Says:

    Vaughn - Excellent, thanks for the clarification. I’ll update the ‘About’ portion shortly. As to whether I’ll rename the blog, “It’s just an interval”… I’m unsure. :-(

    hfp_rick - Maybe your hat is too small? :-)

    myhobbie - ‘??????’ ? Commenting on the blog or the confusing PHASE definition? And if you like any pics that I’ve posted, LMK and I’ll email you the original size (all shrunk down here on the web a bit for bandwidth economy).

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