Traffic signal

[jakeroot]

I was down in Tucson, Arizona over the weekend. For as uninteresting as the city may be for those who aren't traffic nerds (at least according to my family who live in Phoenix), I've always found the city fascinating. They seem to be on the cutting edge of just about every new traffic control device, intersection configuration, etc. I've never seen so many "foreign" setups in my life.

I came upon this intersection in NE Tucson (Tanque Verde Road @ Sabino Canyon Road), where I noticed that the EB to NB left turn, a double left turn with permissive phasing (as is the way for almost all double lefts in Tucson), featured both a leading green arrow, and a lagging green arrow. I assume this is necessary due to a large amount of traffic performing the maneuver. Nonetheless, I've never seen this phasing used before:

https://youtu.be/1WWBn_6o4oY

Not sure if this has been mentioned before, but the 5-section signals on E Tanque Verde Rd were replaced with FYA's in both directions as of April 2019. Did the phasing change to lag-lag (or lead-lag) with TOD phasing, or was the phasing in the video retained?

April 2019 Street View

EDIT (somehow I deleted this): I have not been back so I'm not sure how it runs. But likely runs with regular phasing now, as the old phasing was necessitated by the 5-section towers.

King County has always used a lot of yellow as well. (Example: https://goo.gl/maps/MvtC8c1LTidyAY9DA) In fact, I don't think I've ever seen any back signals from them, just those backplates with the bit of black inside the yellow border (which does indeed look quite silly).

I think the county's practice for decades is what led cities like Renton and, for a while, Federal Way (and others) to use yellow signals, and to paint the back yellow as well.

[SignBridge]

Jakeroot mentioned lead/lag arrow phasing in that post from 2017. Ten years ago I saw protected-only lead/lag left-arrow phasing in Millbrae, Calif. on S.R. 82 (El Camino Real) not far from San Francisco Airport. Only single left-turn lane though.

[jakeroot]

Jakeroot mentioned lead/lag arrow phasing in that post from 2017. Ten years ago I saw protected-only lead/lag left-arrow phasing in Millbrae, Calif. on S.R. 82 (El Camino Real) not far from San Francisco Airport. Only single left-turn lane though.

I updated my post to reflect my total omission of any response (somehow it got deleted). I think that signal in Tucson runs with regular phasing now.

The signal that you mentioned, it was just a simple lead/lag operation? The video that I posted above (from 2017) was notable for having both a leading and lagging phase, on either side of a permissive green orb.

[SignBridge]

Right, it was protected-only before and after the thru-green phase, but not automatic. It was actuated by vehicles in the left-turn lane. If no vehicles were in that lane waiting to turn the system would omit that phase as it cycled.

[jakeroot]

Right, it was protected-only before and after the thru-green phase, but not automatic. It was actuated by vehicles in the left-turn lane. If no vehicles were in that lane waiting to turn the system would omit that phase as it cycled.

Interesting. I've seen things like that before, but not because it was programmed to do so. Just happened as part of normal actuation.

Seems like your signal could do with permissive phasing!

[SignBridge]

The area where I saw those signals back in 2010 are in Santa Mateo County just south of San Francisco. Virtually every signalized intersection I saw out there was protected only left turns, even at intersections where you wouldn't think turn arrows were needed. I saw no permissive left-turns there at all. It seems like when they signalize an intersection in that area, they do it 100% with ped-signals and left-turn arrows. The authorities out there must have a heck of a budget for traffic signals. LOL

[UnumProvident101]

I'm from Chattanooga, Tennessee and I'm wondering what model of traffic light this is
https://goo.gl/maps/TtgVii3Vfa4zMqXX7

[stevashe]

The area where I saw those signals back in 2010 are in Santa Mateo County just south of San Francisco. Virtually every signalized intersection I saw out there was protected only left turns, even at intersections where you wouldn't think turn arrows were needed. I saw no permissive left-turns there at all. It seems like when they signalize an intersection in that area, they do it 100% with ped-signals and left-turn arrows. The authorities out there must have a heck of a budget for traffic signals. LOL

Yeah it's weird, they seem to really like their protected lefts there, and elsewhere in Northern California too. In fact, I don't think I've seen a single permitted/protected signal in northern CA, and I've been all around the Bay Area and Sacramento and a few other places, it's like they've got something against them.

[jakeroot]

I'm from Chattanooga, Tennessee and I'm wondering what model of traffic light this is
https://goo.gl/maps/TtgVii3Vfa4zMqXX7

Those are PEEK signals. My favorite! They could also be another brand that I can't recall the name of, but have identical styling. I pretty much refer to all of them as PEEK signals.

The area where I saw those signals back in 2010 are in Santa Mateo County just south of San Francisco. Virtually every signalized intersection I saw out there was protected only left turns, even at intersections where you wouldn't think turn arrows were needed. I saw no permissive left-turns there at all. It seems like when they signalize an intersection in that area, they do it 100% with ped-signals and left-turn arrows. The authorities out there must have a heck of a budget for traffic signals. LOL

Yeah it's weird, they seem to really like their protected lefts there, and elsewhere in Northern California too. In fact, I don't think I've seen a single permitted/protected signal in northern CA, and I've been all around the Bay Area and Sacramento and a few other places, it's like they've got something against them.

They do exist, but are needlessly rare:

Industrial Ave @ Freedom Way, Roseville: https://goo.gl/maps/3LhJ1HHmzJnSgbqR7
Valley Trails/Parkside Drive @ Hopyard Road, Pleasanton: https://goo.gl/maps/TgWKsidDEVL6noQr6
Geary Road @ Putnam/Buena Vista, Walnut Creek: https://goo.gl/maps/gMh4nMYW97Jjn2x29

There are also some doghouse/tower signals out there, but again, needlessly rare.

EDIT: The Pleasanton signal previously featured mast arms without any signal, despite the hardware clearly being there...how very strange:

[UnumProvident101]

I think that the intersection of Morrison Springs Road @ Red Bank High School has the same type of traffic light
https://goo.gl/maps/ZbXCcfknjih5wC6w6

[stevashe]

They do exist, but are needlessly rare:

Industrial Ave @ Freedom Way, Roseville: https://goo.gl/maps/3LhJ1HHmzJnSgbqR7
Valley Trails/Parkside Drive @ Hopyard Road, Pleasanton: https://goo.gl/maps/TgWKsidDEVL6noQr6
Geary Road @ Putnam/Buena Vista, Walnut Creek: https://goo.gl/maps/gMh4nMYW97Jjn2x29

There are also some doghouse/tower signals out there, but again, needlessly rare.

Yeah it's strange, the only real reason to not have permitted phasing is to reduce pedestrian conflict, but then you'd think they'd only avoid it in areas with high foot traffic, not everywhere.

[jakeroot]

I think that the intersection of Morrison Springs Road @ Red Bank High School has the same type of traffic light
https://goo.gl/maps/ZbXCcfknjih5wC6w6

The all-yellow signals are indeed PEEKs. I can't remember what the black-front signals are called.

Yeah it's strange, the only real reason to not have permitted phasing is to reduce pedestrian conflict, but then you'd think they'd only avoid it in areas with high foot traffic, not everywhere.

It's something to do with California's state-supplied MUTCD. Honestly, it's the case throughout California, except in Los Angeles-proper which remains as a high-profile holdout (for good reason IMO). A lot of side approaches to arterial intersections in California seem to use fully-permissive phasing, but it's like there was a huge period where either fully-permissive or fully-protected were the only options. IIRC, Los Angeles was the first California municipality to adopt protective/permissive 5-section signals.

[UnumProvident101]

how common is this setup
https://goo.gl/maps/5n1iRm9ycjGy3SSE7

[UnumProvident101]

this intersection in Red Bank, TN still has 4 old traffic lights except 3 being replaced in 2014
https://goo.gl/maps/gB9FR5M7WPxuHE5e7

[UnumProvident101]

does anyone know what brand of traffic light this is
https://goo.gl/maps/ffW4Tfcr9h99LEsU7

[Mark68]

how common is this setup
https://goo.gl/maps/5n1iRm9ycjGy3SSE7

I'd say it's relatively common when there is a railroad track parallel to a major arterial. See this example really close to my work:

https://goo.gl/maps/4p8FvrvPeSjCTdmy8

In this case, the tracks are part of the Denver RTD light rail.

[stevashe]

Yeah it's strange, the only real reason to not have permitted phasing is to reduce pedestrian conflict, but then you'd think they'd only avoid it in areas with high foot traffic, not everywhere.

It's something to do with California's state-supplied MUTCD. Honestly, it's the case throughout California, except in Los Angeles-proper which remains as a high-profile holdout (for good reason IMO). A lot of side approaches to arterial intersections in California seem to use fully-permissive phasing, but it's like there was a huge period where either fully-permissive or fully-protected were the only options. IIRC, Los Angeles was the first California municipality to adopt protective/permissive 5-section signals.

I thought it might be something like that, I was reading through their MUTCD at some point because I was curious about exactly which of the more unique features of California's roads were due to their state MUTCD, but I think I only got through signs and pavement markings so far. I think I'll go investigate the traffic signal section now to see what it says...

[jakeroot]

Yeah it's strange, the only real reason to not have permitted phasing is to reduce pedestrian conflict, but then you'd think they'd only avoid it in areas with high foot traffic, not everywhere.

It's something to do with California's state-supplied MUTCD. Honestly, it's the case throughout California, except in Los Angeles-proper which remains as a high-profile holdout (for good reason IMO). A lot of side approaches to arterial intersections in California seem to use fully-permissive phasing, but it's like there was a huge period where either fully-permissive or fully-protected were the only options. IIRC, Los Angeles was the first California municipality to adopt protective/permissive 5-section signals.

I thought it might be something like that, I was reading through their MUTCD at some point because I was curious about exactly which of the more unique features of California's roads were due to their state MUTCD, but I think I only got through signs and pavement markings so far. I think I'll go investigate the traffic signal section now to see what it says...

I honestly haven't looked at it myself; what I said was just what I've heard through the grapevine. Nevertheless, I'm sure there's some truth to it. CA seems to have the most consistent signal design strategy of any US state. Surely it has something to do with their state-supplied MUTCD (something WA lacks and is perhaps why so many municipalities here have different signal designs, and thus different operational strategies).

[jakeroot]

how common is this setup
https://goo.gl/maps/5n1iRm9ycjGy3SSE7

Reminds me a lot of this approach in Aberdeen, WA (adjacent to several other identical approaches), just without the railway crossing.

this intersection in Red Bank, TN still has 4 old traffic lights except 3 being replaced in 2014
https://goo.gl/maps/gB9FR5M7WPxuHE5e7

I quite like the right-turn overlap signal for northbound to eastbound traffic. Definitely strange to see only some signals upgraded, although I see stuff like that in WA from time to time, mostly as part of minor operational upgrades (protected-only to protected-permissive, for instance, or even upgrades to ped signals, which wouldn't necessitate all new signal heads).

does anyone know what brand of traffic light this is
https://goo.gl/maps/ffW4Tfcr9h99LEsU7

I believe those signals are Eagle "Bubblebacks", or possibly the Siemens Eagle (the newer variation).

[UnumProvident101]

some of the traffic lights in that intersection in Red Bank, TN were replaced due to storms knocking them down

[UnumProvident101]

this is the most dangerous intersection in Chattanooga, TN
https://goo.gl/maps/vVCR5CuKdzSReCxp7

[jakeroot]

this is the most dangerous intersection in Chattanooga, TN
https://goo.gl/maps/vVCR5CuKdzSReCxp7

Define "dangerous".

[UnumProvident101]

that intersection is so busy

[Brandon]

how common is this setup
https://goo.gl/maps/5n1iRm9ycjGy3SSE7

More common than you might think.
https://goo.gl/maps/cX9pk7K7p3MKtij19
https://goo.gl/maps/thte8Ex8WReKPJYC6 (site of an infamous school bus/train crash in 1995)
https://goo.gl/maps/tfteJjJVcZtLr4cr8
https://goo.gl/maps/RfgYEZBwjaNNDtX3A

[Brandon]

that intersection is so busy

By itself, "busy" does not a dangerous intersection make.  This is a pretty standard "+" intersection.