In the Los Angeles area more programmable left turn signal are getting replace with brighter led red arrow left turn signals because they are more visiable. California use more red arrows because of they more understandable and do not need to be block from through traffic lanes.
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For those who don't know. Here is a programmable visibility signal:
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fupload.wikimedia.org%2Fwikipedia%2Fcommons%2Fthumb%2F0%2F0e%2FFirst_and_Mill_3Ms_img07.jpg%2F800px-First_and_Mill_3Ms_img07.jpg&hash=45ecb759c965142502fd1a8b316c5af3d26f3f12)
Most are developed by 3M. I think everyone knows about the LED ones.
Honestly, the programmable ones were sometimes a pain in the ass to read. Not sure how many people here have taken optical physics, but it uses two different glass lenses to diffuse the light from a high-powered beam. I believe they're discontinued in the last decade since LEDs are frankly better and cheaper to maintain.
Furthermore, you can still have the LED lights diffracted with blinds so you can only see it in your lane, and you can actually see it far away if you're looking directly straight into it. The programmable ones are often invisible until you're within 200 feet from the mast arm.
I totally agree that the programmable signals are hard to read from any significant distance. What was their supposed advantage over fluorescent incandescent signals, then?
Quote from: Takumi on July 09, 2012, 11:29:04 PM
I totally agree that the programmable signals are hard to read from any significant distance. What was their supposed advantage over fluorescent signals, then?
They were louvered so you wouldn't get the left turn signal mixed up with the mainline signal. You can't really do that too easily with a conventional signal (although blinds are used). The visibility is programmable or adjustable based off of the angle of the lenses, but I think the visibility just deteriorates over-time. The biggest issue with the damn things were cost.
McCain still makes a version of them and they are still used on some new installations in California.
I thought I had seen some manufacturer making a LED programmable signal, that could be programmed from a cell phone. Are those still around/anyone with experience with those?
Quote from: KEK Inc. on July 09, 2012, 11:33:37 PM
They were louvered so you wouldn't get the left turn signal mixed up with the mainline signal. You can't really do that too easily with a conventional signal (although blinds are used). The visibility is programmable or adjustable based off of the angle of the lenses, but I think the visibility just deteriorates over-time. The biggest issue with the damn things were cost.
I think their biggest problem is that when they are approached from a distance, they give the driver a stimulus of "oh fuck, the signal's out ... batten down the hatches, this ain't gonna be pretty".
Quote from: KEK Inc. on July 09, 2012, 11:33:37 PM
Quote from: Takumi on July 09, 2012, 11:29:04 PM
I totally agree that the programmable signals are hard to read from any significant distance. What was their supposed advantage over fluorescent signals, then?
They were louvered so you wouldn't get the left turn signal mixed up with the mainline signal. You can't really do that too easily with a conventional signal (although blinds are used). The visibility is programmable or adjustable based off of the angle of the lenses, but I think the visibility just deteriorates over-time. The biggest issue with the damn things were cost.
The other common use for programmable signal heads was for cases with very closely spaced intersections. The theory was that using programmable heads at the second intersection reduced the chances that those signals would distract the driver from seeing the signals at the first intersection.
The principal headache for DOTs using programmable signal heads was that the bulbs had a very short life expectancy and were expensive to replace.
AFAIK, 3M has discontinued making the programmable heads.
Quote from: roadman on July 10, 2012, 10:48:41 AM
AFAIK, 3M has discontinued making the programmable heads.
According to Wikipedia, 3M discontinued them in 2007. McCain still has them on their website: http://www.mccain-inc.com/traffic/item/green-products/programmable-traffic-signal.html (http://www.mccain-inc.com/traffic/item/green-products/programmable-traffic-signal.html)
Quote from: roadman on July 10, 2012, 10:48:41 AM
The other common use for programmable signal heads was for cases with very closely spaced intersections. The theory was that using programmable heads at the second intersection reduced the chances that those signals would distract the driver from seeing the signals at the first intersection.
I know of at least one such instance where programmable heads are used only for the green indication. (http://goo.gl/maps/pp5x) Is/was that a common practice?
I can only think of one use of a programmable visibility signal in Kansas - at the intersection of 6th and Massachusetts in Lawrence, where much of the traffic (and US 40/59) turns from the east to the north. The PVS heads are used for traffic proceeding straight-through on 6th.
Left turning traffic has a traditional signal head, with a red arrow. It remains, to date, the only protected-only traffic signal in Lawrence that uses the red arrow (although there are several Flashing yellow arrow signals, all other protected-only signals, including one at an intersection where a FYA was used on the cross street, still use a circular red indication.)
EDIT: have spotted several uses of PV signals outside of Lawrence - all are on the Missouri side of the KC metro.
Quote from: Central Avenue on July 10, 2012, 06:01:58 PM
Quote from: roadman on July 10, 2012, 10:48:41 AM
The other common use for programmable signal heads was for cases with very closely spaced intersections. The theory was that using programmable heads at the second intersection reduced the chances that those signals would distract the driver from seeing the signals at the first intersection.
I know of at least one such instance where programmable heads are used only for the green indication. (http://goo.gl/maps/pp5x) Is/was that a common practice?
Wow! I'd say that's extremely rare. I've never seen or heard of such a setup. In my experience with signalized intersections, it's always been red/yellow/green PV heads, or all just regular. I've ever seen only one street get PV signals, or even just one direction for one reason or another, but never just the green light.
Quote from: signalman on July 11, 2012, 03:34:36 AM
Quote from: Central Avenue on July 10, 2012, 06:01:58 PM
Quote from: roadman on July 10, 2012, 10:48:41 AM
The other common use for programmable signal heads was for cases with very closely spaced intersections. The theory was that using programmable heads at the second intersection reduced the chances that those signals would distract the driver from seeing the signals at the first intersection.
I know of at least one such instance where programmable heads are used only for the green indication. (http://goo.gl/maps/pp5x) Is/was that a common practice?
Wow! I'd say that's extremely rare. I've never seen or heard of such a setup. In my experience with signalized intersections, it's always been red/yellow/green PV heads, or all just regular. I've ever seen only one street get PV signals, or even just one direction for one reason or another, but never just the green light.
I seem to remember seeing a 5-section doghouse PPLT display where programmable heads were only used for the circular green and circular yellow displays. I think it was at one of two closely-spaced intersections in Henderson, NV, but I can't for the life of me think of where it was. I recall thinking that was really unusual.
It makes more sense to use the LED ones anyways. I rarely even see it being useful anymore, even the McCain ones that have become ever so common in certain parts of LA, they seem to be a waste.
I guess I'm confused by the "LED vs. programmable visibility" thing. McCain's web page about their programmable signals mentions that they can use incandescent or LED lamps.
Fwiw, the intersection of US 52 and IN 38 once had 3Ms all over due to the shallow angle of the intersection; they were changed around 2000 to regular signals with louvers and the louvered signals were much, much harder to see, especially during the day, because of the louvers. It seemed like the louvers had extra-thick material that blocked out quite a bit of the signal faces.
US 231 and Grant St. in West Lafayette, Ind. also had 3Ms for a long time due to a shallow angle but those were recently replaced with ordinary signals without any louvers.
While both of those are INDOT installations, it's interesting that a couple local city installations continue to use programmables, Union/Earl/Hedgewood in Lafayette is a double intersection with possible green for the second signal while the first is red and uses what appear to be McCains (round faces); Salisbury/Grant in West Lafayette has a shallow angle and uses 3Ms for those approaches. Both date to the early 90s at the youngest and are still kicking.
Quote from: signalman on July 11, 2012, 03:34:36 AM
Quote from: Central Avenue on July 10, 2012, 06:01:58 PM
Quote from: roadman on July 10, 2012, 10:48:41 AM
The other common use for programmable signal heads was for cases with very closely spaced intersections. The theory was that using programmable heads at the second intersection reduced the chances that those signals would distract the driver from seeing the signals at the first intersection.
I know of at least one such instance where programmable heads are used only for the green indication. (http://goo.gl/maps/pp5x) Is/was that a common practice?
Wow! I'd say that's extremely rare. I've never seen or heard of such a setup. In my experience with signalized intersections, it's always been red/yellow/green PV heads, or all just regular. I've ever seen only one street get PV signals, or even just one direction for one reason or another, but never just the green light.
There used to be an assembly at the US 81/SH 66 intersection in El Reno, Oklahoma that used green-only PV sections for northbound traffic. IIRC, they were the ones that showed solid green from a distance, but straight-ahead arrows once you got closer.
Tulsa used to be creative with PV sections, as well. The city standard for left-turn signals used to specify PV sections for red and yellow, with a standard 12" section for the left arrow.
The original Tulsa standard for protected/premissive left turn signals were four-section, standard 12" red, green and green arrow, with a PV yellow. The yellow light did double duty for both the green and arrow indications.
A former common setup, locally, was to use three standard balls (red, yellow, green) with a programmable color changing lamp underneath. The programmable lamp would be an arrow that changed from green to yellow. I wish I had some photographs of them. :-(
Quote from: Tom89t on July 09, 2012, 11:03:16 PMIn the Los Angeles area more programmable left turn signal are getting replace with brighter led red arrow left turn signals
Oregon has been steadily getting rid of the programmable lights for many years. Seemed to be big in the 1980s, not so much anymore.
The only new installation I know if is in Tigard on S.W. Bonita Road at 74th Avenue, and that is only because of the proximity to the WES commuter rail line and Portland & Western Railroad tracks (there's actually two separate railroad lines that parallel each other). There is a traffic signal mounted inbetween the two sets of tracks (with a regular railroad crossing signal before it) and a stop bar before the railroad track; so the "home" signal at 74th is a PV signal so that motorists from a distance see the first signal well before the street intersection.
http://maps.google.com/maps?q=Tigard,+OR&hl=en&ll=45.415194,-122.752819&spn=0.005053,0.011362&sll=42.582411,-123.74588&sspn=0.175689,0.363579&hnear=Tigard,+Washington,+Oregon&t=m&z=17&layer=c&cbll=45.415189,-122.753073&panoid=ZTwAcJrY8FagI-6Lto2WgQ&cbp=12,80.95,,0,-4.01
In case you were wondering how the "programmable" bit works. Basically, there's a mask with a triangular hole (formed with that metal tape) in between the lamp and the lens. That, combined with a Fresnel lens, blocks the lamp from appearing at undesired angles. As far as I could tell there's no reason you couldn't replace the lamp with LEDs and have a programmable LED lamp.
Quote from: PurdueBill on July 11, 2012, 11:38:39 AM
I guess I'm confused by the "LED vs. programmable visibility" thing. McCain's web page about their programmable signals mentions that they can use incandescent or LED lamps.
Fwiw, the intersection of US 52 and IN 38 once had 3Ms all over due to the shallow angle of the intersection; they were changed around 2000 to regular signals with louvers and the louvered signals were much, much harder to see, especially during the day, because of the louvers. It seemed like the louvers had extra-thick material that blocked out quite a bit of the signal faces.
US 231 and Grant St. in West Lafayette, Ind. also had 3Ms for a long time due to a shallow angle but those were recently replaced with ordinary signals without any louvers.
While both of those are INDOT installations, it's interesting that a couple local city installations continue to use programmables, Union/Earl/Hedgewood in Lafayette is a double intersection with possible green for the second signal while the first is red and uses what appear to be McCains (round faces); Salisbury/Grant in West Lafayette has a shallow angle and uses 3Ms for those approaches. Both date to the early 90s at the youngest and are still kicking.
Dialight makes LED Lamp Modules for Programmable Visibility (PV) Signals (3M and McCain)
http://www.signalcontrol.com/products/dialight/Dialight_PV_Modules.pdf
Personally, when it comes down to limited distancing, I prefer programmable visibility signals over louvers: conventional and geometrically programmed. In Houston, there were once 3M PV signals located at Beltway 8 and J.F.K. Blvd. They have since been replaced with Pelco Louvers. One time I was northbound on J.F.K. waiting for the light to turn green at Beltway 8 westbound. I was
barely able to see the traffic signal up close.
Here's one installed about six or seven years ago in town.
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fi837.photobucket.com%2Falbums%2Fzz298%2Fmidamcrossrds%2F100_2273.jpg&hash=3c9ce6771e58cc8077a0efe121e801648eae6498)
It was installed as the second set of signals in succession, but the first set was never installed.
In addition to the signal in Lawrence, I've spotted several PV signals on the Missouri side of the KC Metro. In particular, I believe the signal at MO 291 and Leonard Street in Liberty is an example of a PV signal retrofitted with LED bulbs.
Quote from: signalman on July 11, 2012, 03:34:36 AM
Quote from: Central Avenue on July 10, 2012, 06:01:58 PM
Quote from: roadman on July 10, 2012, 10:48:41 AM
The other common use for programmable signal heads was for cases with very closely spaced intersections. The theory was that using programmable heads at the second intersection reduced the chances that those signals would distract the driver from seeing the signals at the first intersection.
I know of at least one such instance where programmable heads are used only for the green indication. (http://goo.gl/maps/pp5x) Is/was that a common practice?
Wow! I'd say that's extremely rare. I've never seen or heard of such a setup. In my experience with signalized intersections, it's always been red/yellow/green PV heads, or all just regular. I've ever seen only one street get PV signals, or even just one direction for one reason or another, but never just the green light.
Heck, back in the 80s & 90's, 3Ms were all over the place in Toledo, OH -- including some intersections (mostly above protected left-turn lanes) where there was only a programmable red-ball head with regular yellow and green arrow heads below them.
I own two programmable signal heads in my collection. One is the all-to-familiar model made by 3M. Most people are aware of how it works from the amount of information out there and the videos.
Last year I picked up an electronic steerable beam signal made by Intelight. This is decades ahead the 3M or McCain programmable signals. It uses a logic based LED array and uses software to adjust the light beams. The signal has two ways to program it. Hardwire plug into a laptop with software, or with a wireless programming kit and PDA or Smartphone App. I just bought the hardwire kit because it is significantly cheaper. (3-figure price versus a 4-figure)
This signal also keeps logging for diagnostics such as light intensity, time the light is illuminated, voltages, temperatures, and preventive failure analysis.
It also has a logic based dimming system that allows the signal intensity to dim based on outside ambient conditions. The back of each signal housing has a heat sink to keep the internal electronics cool. The signal has the options for upgrading the firmware or adding built in video cameras within the housings
The Intelight head is by far my favorite signal head, it was not easy to find or cheap....but I'm glad I got to pick one up
-Nick
Programming the Intelight Electronically Steerable Beam signal
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fi46.tinypic.com%2F35jbdwj.jpg&hash=9b6dfeee55df9210db591ac418ca20d3ca18180d)
-Nick