LED traffic signals

[Alps]

This thread can evolve with news, ideas, discussions... starting off with some news

http://news.yahoo.com/s/ap/20091216/ap_on_re_us/us_snow_covered_stoplights

[Hellfighter]

It'll be interesting to see how that plays out here in Michigan, where we're transitioning to LED Traffic Lights.

[agentsteel53]

little wiper blades?  Install in center of light and allow to rotate freely to clear snow before it sticks. 

[mightyace]

Energy-efficient traffic lights can't melt snow
http://news.yahoo.com/s/ap/20091216/ap_on_re_us/us_snow_covered_stoplights

Yeah, let's save some electricity.  Who cares if a few more people die in traffic accidents, they're far too many of them anyway.

[rawmustard]

This thread can evolve with news, ideas, discussions... starting off with some news

http://news.yahoo.com/s/ap/20091216/ap_on_re_us/us_snow_covered_stoplights

I know this was the subject of a Car Talk puzzler several years ago. Always interesting to see how the media reacts to a problem that really isn't new. Short of using cutaway visors (so there's less surface area for snow to stick), there really isn't a practical solution.

[Chris]

LED traffic signals consume less energy. That's problematic in snowy states, as traffic signals become invisible due to snow sticking to it and doesn't melt. We had a major problem here a year ago when nearly all traffic signals were invisible during snowfall. It was the rush hour from hell.

Maybe they need to install some heating device that only works during winter. That way you still save energy 9 months a year, but you keep the signals visible for the other 3 months. I don't think installing wiper blades is really an answer, way too maintenance sensitive. Have crews driving all over town cleaning traffic signals isn't very efficient either.

[agentsteel53]

is there a way to make the snow not stick?  it seems it's the upper surface of the hood that is the problem, and the snow is resting against the glass, not actually sticking to that.  How would glare be affected if the top quadrant of the hood (say, from 10 o'clock to 2 o'clock, plus or minus an "hour" each way) were eliminated?

[Chris]

We have them without the hoods. The problem remains if the snow is falling in combination with wind. It just sticks to it like it sticks to traffic signs or directional signage.

[wytout]

I guess our snow isn't cold enough in CT.  Most state and local roads here have been transitioning to LED's for 10 years now, and they are the predominant luminary found in most traffic lights.  Even in the worst snows, wind and cold we've had, I don't think I've ever seen one being blocked by crusted snow.

[Duke87]

I guess our snow isn't cold enough in CT.  Most state and local roads here have been transitioning to LED's for 10 years now, and they are the predominant luminary found in most traffic lights.  Even in the worst snows, wind and cold we've had, I don't think I've ever seen one being blocked by crusted snow.

I think it's less a matter of temperature and more a matter of the nature and severity of the storm. Consider the locations where this problem has developed: Milwaukee, Oswego, Green Bay, Saint Paul, Des Moines.... these are places that get more and larger snow storms than Connecticut (lake effect, prairie winters...).

[wytout]

is there a way to make the snow not stick?  it seems it's the upper surface of the hood that is the problem, and the snow is resting against the glass, not actually sticking to that.  How would glare be affected if the top quadrant of the hood (say, from 10 o'clock to 2 o'clock, plus or minus an "hour" each way) were eliminated?

LED's seem bright enough even in direct sunlight, that maybe the visors could simply be eliminated altogether.  Unlike the old incandescent/lens lamps, there is almost never a time that an LED assembly can't be determined without the visor being in place.

[SSOWorld]

The purpose of the hood can be two-fold.  it prevented sunlight from dimming the light - and it prevents cross-traffic from "cheating" (looking at the cross light rather than their light)

[mightyace]

it prevents cross-traffic from "cheating" (looking at the cross light rather than their light)

Of course, that is not always effective at night as light will reflect off the hoods and other nearby objects.

IMHO Watching the other light to anticipate yours turning green is not "cheating."  However, I've stopped doing it for a more practical reason.  Too many people in Middle TN run the light as they turn red or just after they turn red, so starting as soon as you get the green is an invitation to get T-boned. 

[Scott5114]

Of course, that would be their fault, so with luck in the insurance process you may get [Rich Fields] a brand new caaaaaaahhh! [/Rich Fields]

[mightyace]

Of course, that would be their fault, so with luck in the insurance process you may get [Rich Fields] a brand new caaaaaaahhh! [/Rich Fields]

At least my heirs will, anyway. 

[agentsteel53]

it prevents cross-traffic from "cheating" (looking at the cross light rather than their light)

what's wrong with cheating?  I for one really like to "cheat", as I drive a stick shift, and I can anticipate the green and get off the line a couple fractions of a second more efficiently if I use the cross-light turning red as my "put car back in gear and prepare to raise the clutch" indicator.

[Ian]

OT about LEDs. I found out that the intersection of NH 106 and NH 9 near Concord Heights, NH, was the first intersection in the nation to be equipped with green LED traffic signals! Next time I go their, I will be sure to snap some shots of those LEDs since the originals are still lit (well, they're LED's, so of course).

[agentsteel53]

what year was this LED light installed?

[Ian]

what year was this LED light installed?

According to Wikipedia, the exact date is May 17, 1996

[Duke87]

The purpose of the hood can be two-fold.  it prevented sunlight from dimming the light - and it prevents cross-traffic from "cheating" (looking at the cross light rather than their light)

Drivers taking a peek at the light in the other direction isn't an issue.
On the other hand, drivers seeing the other direction's green light and thinking it's theirs is, particularly at intersections where two streets meet at a significant angle and so the other lights are sort of facing you.

[jjakucyk]

OT about LEDs. I found out that the intersection of NH 106 and NH 9 near Concord Heights, NH, was the first intersection in the nation to be equipped with green LED traffic signals! Next time I go their, I will be sure to snap some shots of those LEDs since the originals are still lit (well, they're LED's, so of course).

I wouldn't be so sure.  I've seen a handful of older (not sure how old, but probably late 90s or early 00s) LED signals in North Carolina and a few here in Ohio that are going bad.  Several of the individual elements have gone out, usually in some sort of strange pattern, with others flickering badly.  It's an odd thing to see, but I guess it illustrates how it's not the individual LEDs themselves, but the circuitry controlling them that eventually fails. 

[Ian]

OT about LEDs. I found out that the intersection of NH 106 and NH 9 near Concord Heights, NH, was the first intersection in the nation to be equipped with green LED traffic signals! Next time I go their, I will be sure to snap some shots of those LEDs since the originals are still lit (well, they're LED's, so of course).

I wouldn't be so sure.  I've seen a handful of older (not sure how old, but probably late 90s or early 00s) LED signals in North Carolina and a few here in Ohio that are going bad.  Several of the individual elements have gone out, usually in some sort of strange pattern, with others flickering badly.  It's an odd thing to see, but I guess it illustrates how it's not the individual LEDs themselves, but the circuitry controlling them that eventually fails. 

Yeah, and if you go to Rhode Island, a lot of the LED signals there are burning out. Check out on photo of mine I took this past Spring:
http://picasaweb.google.com/Iansignal/RhodeIslandTrafficSignalsAndRoadSigns#5324332473914119986

[jjakucyk]

Yeah, those ones with the circular pattern are the only ones I've seen going bad though.  I don't know if it's simply a different manufacturer or a different technology altogether, but I've never seen any of the following more gridded LEDs go bad yet.

[Truvelo]

Are there any incandescent traffic lights remaining in the US? All the ones I've seen are LED.

[agentsteel53]

Are there any incandescent traffic lights remaining in the US? All the ones I've seen are LED.

there are plenty, but they tend to be along less important or older routes.