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Protected Left Turns in Tucson AZ

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--- Quote from: Roadwarriors79 on October 24, 2022, 07:40:00 PM ---
--- Quote from: JKRhodes on October 24, 2022, 01:18:17 AM ---Stayed in Chandler, AZ over the weekend and noticed several intersections with four aspect FYA heads and permissive left turns for dual left turn lanes near the mall.

I figured most cities in the valley would be distancing themselves from "tucson permissive dual lefts", not adopting them.

--- End quote ---

Most valley cities do not do what Tucson historically does, at least not all the time. Most of the dual lefts in Chandler that have FYA are on time-of-day phasing. Other than a few intersections in Peoria, most of the valley has stuck with standard protected dual left signals.

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Most of the dual FYA lights in Peoria are at places where a major road dead ends into a residential road or parking lot. In these cases, actually having to yield on the yellow arrow almost never happens, as most traffic coming out the other side is usually either turning right (usually on red), or left. More often than not though the FYA doesnt even need to come on, as there is no need for the other side's straight through to even turn green. The one car that does go straight every hour or so gets to go before the other side gets the FYA. There are rare cases where a car going straight approaches an already green light with traffic still turning left on FYA, which can cause issues, however I've seen this happen on single lefts, and even still this hardly ever happens (83 x peoria, peoria x grand, rio vista x thunderbird, 83 x LPP),-112.2363858,3a,37.5y,54.95h,89.34t/data=!3m6!1e1!3m4!1ss043bHS6Unfm92jlIeM-5Q!2e0!7i16384!8i8192

We do have a diamond interchange (AZ-303 and LPP) which uses a 5 section green circle for permissive lefts with double turn lanes, however its so low volume that the double lanes are completely pointless at this intersection. Diamond interchanges are perfect for dual permissive lefts, as they dont suffer from visibility problems that normal intersections have. Theres another one with the same setup over at northern parkway and sarival in Surprise. Far West valley (especially Peoria) is known for overbuilding the - out of everything.,-112.2497679,3a,28y,352.02h,88.4t/data=!3m6!1e1!3m4!1s_rLk_i7PKSdtFecMPdso3Q!2e0!7i16384!8i8192

Even stranger is that we have two intersections (75 x cactus, 75 x peoria) that were converted from single left on yield to double protected a few years ago, but they installed an FYA signal head that never gets used. It malfunctioned one day two years ago and actually gave the FYA, but it was fixed the next day. These intersections dont even need double lefts anyway. Its not uncommon to see only 5 or so cars turning left even during rush hour. Also cycles are long in peoria, so theres plenty of time with ample gaps in traffic, but nope. There is no TOD phasing either, as its still red even as late as 3:00 am! Double lefts look better on paper, so double left it is!,-112.2197099,3a,37.5y,276.27h,87.54t/data=!3m6!1e1!3m4!1sO7KDIYGRKcVMLf0oKpXgoQ!2e0!7i16384!8i8192


--- Quote from: Roadwarriors79 on October 25, 2022, 02:22:11 PM ---Tucson having a lot of "quirks" is pretty accurate. Even more noticeable since the other agencies in the area (Oro Valley, Marana, ADOT, Pima County DOT) all tend to be more conventional. Keep things simple whenever possible.

Something loosely related, I always wondered how Tucson, which seems to hate most freeways and highways, managed to get a state highway number that actually makes sense (AZ 210) while the Phoenix area seems to have a bunch of random numbers for their newer freeways.

--- End quote ---

If you mean that "AZ 210" makes sense, in the sense of it possibly being an Interstate number, it does in terms of being "close" to it's parent, but a 210 number it should have been further west.   In Phoenix metro perhaps.    Personally would have used "810" instead of "210" as Tucson is farther East in the state.   What was the Tucson planning mentality, back in the day?  Take the Federal allotments, (10 & 19) and not plan for anything else?   No one saw the writing on the wall?  Meaning increased growth, and transplants?  Very similar to Albuquerque in some ways. Yep, Phoenix seems to have had the same problem as well, it took a Maricopa County sales tax approval in the mid eighties to get the loops there we have today.   


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