LED Stoplights Failing in Winter

LED Lights Don’t Melt Snow on Traffic Lights, Hiding Signals From Drivers

By ELISABETH LEAMY and VANESSA WEBER
Jan. 8, 2010

A huge swath of the country is getting snow and it’s raised an unusual and potentially dangerous problem for motorists.

Click picture to see report

Communities across the country are converting to LED traffic lights, but these lights don’t emit heat, so snow doesn’t melt like it would with a regular incandescent bulb. In some cases, Drivers then can’t see the signals.

During a snow storm last year, Lisa Richter of Oswego, Ill., had a green light and was turning left. But police say a driver in the oncoming lane blew through his red light and plowed into her, killing her instantly.

This wasn’t a regular accident. Police said this traffic light, blocked by snow, contributed to the crash. The light was an LED signal, which doesn’t emit heat, so snow doesn’t melt like it would with a regular incandescent bulb.

Cities and states across the country that have converted to LEDs report an energy cost savings of up to 80 to 90 percent.

In Green Bay, Wisc., where all traffic lights are now LEDs, December’s incredible snowfall caused many to be packed with flakes.

After their intense storm last month, some drivers in Madison, Wisc., noticed their neighborhood LED signals were hiding.

“I know that the stoplights are there, but if I didn’t, it would have been very easy to fly right through them,” one driver said. “And especially with the off ramp right on the interstate, it could be a very dangerous situation.”

The state of Wisconsin switched to LEDs in 2002 to achieve the massive energy cost savings. Maintenance costs are also much lower because LEDs last a long time. Incandescent bulbs usually have to be replaced every 2 years.

“With LEDs, we have some of our heads that were installed in 2002 still operational today,” said Wisconsin state traffic signal systems engineer Joanna Bush.

Another advantage of LEDs: Bush said the old incandescent bulbs could pose safety problems of their own.

“When they fail, they go dark, like a light bulb at your house. There’s no warning and it’s dark. With the LEDs, it’s a string or two that starts to go out and the driving public might not even notice a change in the LEDs and we can get our crews out to change it.”

ht JRHolm
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180 thoughts on “LED Stoplights Failing in Winter

  1. Yes, but you’ll need crews to go out and scrape ice of the lights, creating some of Obama’s new green jobs.

  2. For what it’s worth, the push to LED traffic lights appears to be motivated largely by significant savings in electricity and maintenance costs, rather than by green pipe dreams. For once these are the unintended consequences of government doing something smart, than of government doing something stupid.

  3. “Not a problem in warm states, but a problem where it snows.”
    Great! It’s only safe to install them in Hawaii!

  4. Why is this a surprise? People who have used LED lights have known this for years. The traffic engineers in cities using them in traffic signals should also have known, and been doing something about it. A small heating element in the light fixture, perhaps? Sounds like a lot of lawsuits waiting to happen to me!

  5. The easy fix is to not have the shield that collects the snow, especially since LED’s shine brighter and don’t need to have the light directed.

    The more expensive fix would be to convert alot of those intersections to roundabouts. By doing so, it makes people more aware of the traffic that is moving around it. I saw an interesting story on one of the cable news stations about a month ago. Some town in Norway took down all of it’s traffic lights and replaced it with roundabouts and has improved traffic flow almost 80% and has cut down on traffic accidents.

  6. Media gets it wrong again!
    LEDs do emit heat, just not a whole lot.
    They are more efficient and thus produce the same light with less wattage dissipated in heat. They are substantially more visible in situations where glare is a problem. Which poison do you want?

  7. Dunno, how biug a problem is this really? I mean how much snow do you have to pack a LED light before you can’t see it at all, and then how many drivers really won’t stop and look around at a defective light?

    As to the heating thing, it would have to be pretty smart with some secondary sensor, otherwise you are throwing away the energy savings.

    I’d be worried that all that : heating element + snow pack sensor + whatever would be deeply unreliable in actual service conditions. After all lights are defintely onthe severe duty service list: water, sun, heat, cold, wind, vibration, general pollution…

  8. Well, personally I prefer them! They’re more reliable than conventional bulbs, give a more crisp light, and use a lot less battery. It’s not too difficult to think that you need to clear snow off them before you drive off, and periodically (if you then drive through a snowstorm). I’ve seen idiots (Gores to you US) all this week in the UK who can’t clear snow off their windscreen (windshield to you US), off the bonnet (hood to you US), or off the roof (roof to you US). They are then shocked when a lump of it falls off as they’re driving along. They ought to use their loaf (head to you US).

  9. starzmom
    If this was known and is known, and cities install them anyway, then they are liable for any death, injury or property damage that results. Companies could never get away with this.
    If governments are allowed to, then it is yet another sign af out-of-control government power.

  10. What should this illustrate? The danger of saving energy by switching to LED instead of incandescent light? How about all other traffic signs that snow over?
    It doesn’t have with climate to do at all. It’s typical of the fear for all that’s not as it used to be. Father never used an LED.

  11. LED lights are superior. We notice them going out more now because of two things:
    a) failing LEDs is a rare event and,
    b) a lot of LED stoplights were installed at the same time in the early oughties, when the technology first came out, and are starting to hit an uptick in failures as they near end of life, esp in harsh environmental conditions.

    It is truly worth it to use LED lighting, it reduces power consumption by 90% over incandescent, and given the percent of our national electric supply that is consumed by lighting, converting all of our lights to LEDs would mean a rather large conservation.

    According to this:
    http://www.cee1.org/eval/db_pdf_es/275es.pdf
    22% of US electric consumption is in lighting. Converting to LED lighting nationwide for everything would therefore reduce consumption overall by 20%. Given electric production is some 70%+ based on carbon emitting fuels, a reduction in emissions by 17% would put us below our 1990 emission levels for a good few years without a significant economic burden (in fact, LED’s have a ROI of under two years, so the economic benefits are actually positive).

  12. The solution seems simple to me. Have a small heater in the traffic light that is controlled by the temperature. Below zero and it switches on, above and it switches off. The electricity saved over using halogen bulbs (which is what I think traffic lights use) will still be substantial.

  13. This doesn’t sound like a real problem, if there is no light showing then slow down. There would have to be a lot of snow before you could not see that there were lights at the junction.

  14. Didn’t the US pass a law prohibiting the sale of incandescent lights by 2010? So maybe the local governments changed them to comply with Federal regulations…

  15. Time for the engineering types to come up with a new design for traffic lights. I am sure there are a variety of designs that could fix this problem from a sensor that switches on a heating element to an angled lens with a silicone slick coating that snow will not stick to.

  16. starzmom (06:26:37) :

    The traffic engineers in cities using them in traffic signals should also have known, and been doing something about it.

    ____________________________________________________________________

    In principle I agree.

    But, it’s not so easy to go against the flow. Especially when the flow is supposedly saving the world.

    There’s a whole lot of things going on that someone somewhere along the line should known better and said something. Some probably are saying something. But their objection alone isn’t enough to stop ‘going green’.

    Going green is pretty much everywhere you look. I saw a FedEx commercial where they said they didn’t have wood tables because the went green. I saw metal in the new table legs…..(scratches head)….. I can’t see how metal is ‘green’-er than wood—but that’s another topic.

    All the record cold and snow though is slowly but surely changing the momentum AGW and ‘going green’ has. But I think even if the world goes in to a modern day little ice age there will still be a small percentage of people talking about global warming and ‘going green’ to save the earth.

    So, don’t be too hard on city engineers. They might be good folk.

  17. anything but new roundabouts! They used to be very popular in the 20’s and 30’s; just about every Texas town had one at the main intersection. They have just about all been eliminated now, thank merciful heaven! (I still know of a couple on the outskirts of Waco and Ft. Worth) They have always been deathtraps, I think when the Dallas roundabout was finally demolished a few years ago the death toll over it’s existence stood at about 300 or so. Sure there are yield signs and speed limit signs – I’ve been on them, still everyone enters at 70mph and just hopes a spot opens up when they get there.

    In horse and buggy days, they were great -but today, they’re just a nonstop demolition derby.

  18. In the past 2 days alone in the US 277 cold records and 417 snowfall records.

    Many roads from San Antonio to across the deep south have ice. Atlanta is especially icy.

    In Florida they say they’ve had ice and frost like this before but never for this many days in a row. The farmers are going to be hurt financially by it.

  19. All they need to do is put a sensor which detects when temps drop below 32 and activate a resistive non-light emitting heat source. Problem solved.

  20. I generally like the LED traffic lights. However, in my area I have noted a failure phenonmenon: The greens seem to have a large number of failed, or failing individual LED’s. The reds and yellows seem to be holding up much better. I haven’t taken a statistical sample, but maybe I will in the next few weeks. I deal with atomic and molecular physics rather than solid state, but I would guess that the dopant for the greens may change the substrate such that temperature extremes are not tolerated well. Could also be the stress of constant on/off cyles.

  21. In the Christmas Eve snowstorm we had in North Texas, it didn’t take long for the LED lights to develop visibility problems. The snow and sleet were blowing sideways in strong winds. If you were driving on unfamiliar roads, as we were, the “hidden” traffic lights were a problem because visibility was poor anyway. Not a reason to give up on LEDs, but there will ultimately need to be another techno-fix to address this particular issue.

  22. What this portends is Hell freezing over when the real thing is replaced with LED imitations. Not many watts down with that.

  23. How much of a problem is this? I don’t know, let’s ask Lisa Richter. . . Sorry can’t. Assuming the person who hit her was sober and acting responsibly, s/he more than likely isn’t enjoying life right now.

    Great that they save 80% of energy. I’d be curious what that converts to in absolute dollars. Then ask the question, how much of the cost drivers are due to politically motivated green regulations which in turn drive up the cost of electricity.

    Before one thinks this is not a big problem, imagine if it occurred to a member of your family or close friend.

  24. photon without a Higgs (07:20:55) :

    Record cold and snow in the past two days, Thursday and Friday, in the US. Florida is getting it the worst. But Watts Up With that red dot in Florida??

    http://mapcenter.hamweather.com/records/2day/us.html?c=maxtemp,mintemp,lowmax,highmin,snow

    86F when the surrounding area is 20F??? The temperature there is bouncing all over the place look at the record for the last week. http://www.wunderground.com/history/airport/KMAI/2010/1/8/WeeklyHistory.html

    Is there anyone in that area that can confirm these wild swings in temp?

  25. Entrepreneurs take note. A new product that all the northen states will have to buy. Traffic light heaters!

    And the control mechanism to turn them on and off from a central control center.

    Ahh, I see the cash rolling in….

    Mike Ramsey

  26. The school zones in our town have been fitted with flashing lights that operate during times when students arrive and leave school. Whe the lights are flashing, the speed limit is reduced in the the school safety zone.

    The problem is that these lights and their controls are freestanding solar powered units.

    For most of the last week, the solar panels have been covered in snow and the lights have not worked. This at a time when visibility is poor and braking conditions treacherous.

    Student safety, or solar? Pick one.

    [Actually there is no epidemic of students mowed down by cars, either before the lights were installed, or now. These devices are merely revenue generating devices that allow traffic cops to double the fines on inattentive motorists during their operation. But that’s a different rant.]

  27. “if there is no light showing then slow down. ”
    At night they could be a little hard to see.
    If you#re new in the area, then you might not see it well either.
    Heck, people sometimes don’t even see red lights.
    I think it’s all abunch of silly actionsm. “Hey look at us! We’re being green!”

    Actually Jeff Id has a good solution…hurry up and patent it!

  28. If there have been a large number of LED signal lamps installed since (say) 2000 and this is the first time that there has been a (reported) fatality I think the risk is acceptable. Perhaps the problem doesn’t occur often because the engineers actually did think about this? Would that really surprise anyone? I hope not.

  29. Maybe if they install a heating element inside with the LED light the problem would be solved. The heating element could also be so designed to give off light. Just thought of something brilliant, why not do away with the LED light if you replace it with a heater element that gives off enough light to be used as a signal light bulb,,, Dah!

    Better yet, take all the signal lights down, remove all the signs and let stupidy sort it all out! There is a town somewhere in Europe that did just that, can’t remember where but the result was that the traffic flowed better and there were less accidents. The people in that town adjusted just fine, bet us americans would never have that ability.

  30. Mark (06:31:00) said :

    “The more expensive fix would be to convert a lot of those intersections to roundabouts. By doing so, it makes people more aware of the traffic that is moving around it. I saw an interesting story on one of the cable news stations about a month ago. Some town in Norway took down all of it’s traffic lights and replaced it with roundabouts and has improved traffic flow almost 80% and has cut down on traffic accidents.”

    In the UK we are doing our best to screw up traffic flows by putting traffic lights on all our roundabouts. The inevitable result of which is that some drivers just ignore them.

  31. My 3 year old just pointed an LED flashlight up to my eye. It does emit heat.

    A few years back I put LED bulbs in the potlights in my home. It was too early. As a previous poster indicated, the current failing LEDs are likely early generation units. Newer ones are cheaper, last longer, have many more colour temperature options.

    They just have to redesign the housing of the lights to prevent snow accumulation

  32. You have to consider the benefits as well as the disadvantages of a thing. In terms of human life, add up the lives saved by LEDs that replaced incandescent red lights that might have burned out and caused a fatal wreck.

  33. The solution is simple. Take a look at the rear window of most any modern automobile. What do you see? Little horizontal lines that comprise the defogger/defroster circuit. Temperature sensors that would turn them on would burn a lot of useless electricity. What is needed is a snow/ice sensor.
    How about turning them on system wide when snow and ice are experienced. They don’t need defogging at 0 deg F and no snow/ice.

  34. @ wws (07:26:23) :

    How is it possible that roundabouts are deathtraps, in my own hometown (wich is in the Netherlands) we had a 4 lane road wich was reduced to a 2 lane and the intersections where replaced by roundabouts. It would not work, traffic would come to a standstill everybody cried.

    Traffic is pretty much as usual, the volume even increased but what was far more spectaculair is the fact that the number of accidents with serious injuries and death on this road was reduced to almost nothing.

    Sometimes you have to do the opposite to make traffic more safe and people should pay attention to their surroundings instead of racing blindly around hoping that the other driver is paying attention. If traffic lights do not work than common sense should.

  35. Not a wild swing. The beginning of the week saw rising temps (IE a return to mild winter weather for Florida) from the 40’s to the 80’s, followed by a severe cold weather event.

    Interesting how warm takes a bit to build up but cold drops in like a cannon ball.

  36. photon–

    I am not being hard on engineers on purpose–I am one, I am married to one, and my brother, son and father in law are engineers also. But its their job to look at all the consequences and angles of the actions they take (or recommend–the engineers probably didn’t make the decisions) and lay them out. And if they didn’t know that snow would build up in the lights, that is a problem. On the other hand, maybe it was the city financial guy who nixed a heater or other fix for the problem. Either way–lawsuit.

  37. Philip T. Downman (06:53:55) :

    What should this illustrate? The danger of saving energy by switching to LED instead of incandescent light? How about all other traffic signs that snow over?
    It doesn’t have with climate to do at all. It’s typical of the fear for all that’s not as it used to be. Father never used an LED.

    Reply
    What does this illustrate? Sloppy engineering.

    If the current media crisis was “Oh my there is a coming Ice Age”, someone might have considered the icing up problem of these new lights and produced a decent, VALIDATED engineering design. Instead we have lights that will fail in snowstorms and bankrupt local governments who are not about to spend money to replace the new lights they just installed a few years ago.

    The cost? People injured and dead. That is not ““typical of the fear for all that’s not as it used to be. Father never used an LED.” That is concern for our fellow humans. Something the left/progressives/marxists or whatever politician is speaking is always proclaiming, but the reality of what they implement as law always seems to be far different.

  38. It is always interesting to see how people blame the light instead of the driver. The lawyers have us well conditioned. “It was a foreseeable defect! It’s the company’s fault! Please send money.”

    Every driver should understand the traffic rule when approaching a non-working traffic signal. It’s the same whether its incandescent or LED. If you cannot see the signal light, STOP. Look for other traffic. Proceed with caution when it is clear to do so. [Everbody else is likely stopping too, so simply take turns].

    Further, even if you have a green light (and can see it) you MUST check for approaching traffic an assure a clear distance BEFORE starting your left turn. The description in the article isn’t clear as to whether the vehicle going through the intersection was in an oncoming lane or the cross street.

    News commentary and shows like 60 Minutes are usually presented from the perspective of the plaintiff’s lawyer.

  39. Re: Failing LEDs

    Let’s not ass-ume that the LEDs themselves are failing. Thanks to RoHS, it could be the lead-less solder connections.

  40. The newly designed roundabouts are not at all the same as the old familiar traffic circles. The design is very different and a lot of the problems that used to exist with the older traffic circles have been removed. We have a couple of roundabouts here in Rochester (MI) and they are highly successful, even though there is a bit of a learning curve.

  41. Come on folks. I am ALL for being skeptical when it comes to “man-made-global-warming”, but if LED lamp installation makes economic sense, then by all means do it! I believe its a fairly straight forward economic calculation that includes well documented (averaged) costs such as; replacement frequency, lamp cost, estimated watt-hour consumption, as well as estimated electricity costs (historic). Example: my calculations for purchase of LED Christmas lights DID NOT make economic sense, in short, in my location, the cost-of-purchase + the cost-to-operate per LED lamp was significantly higher for a 5 year period than the same costs on low wattage conventional lamp. I calculated it was cheaper to buy the conventional $0.03/lamp strands, and throw them away in 5 years. I’m betting by then, LED’s will be super cheap and/or electricity will be super expensive.

    Even when done well, implementation of new technology most certainly solves some problems, and typically presents some new ones. I thought the fix proposed on ABC news of transparent bubble-like shields seemed logical and probably fairly cheap.

  42. Pray we do have some global warming. If cooling continues we’ll use more energy and have less energy security.

  43. On new years day my daughter said “we are not there yet”

    I asked her how advanced we are with LED’s. She is an architectural engineer and is over 1 billion dollars of construction in the design phases.

    LED requires new lighting fistures and products. Just changing bulbs without re engineering is not working well.

  44. LED is the future. There is already technology for increasing brightnes and improving colour. http://www.obducat.com/Default.aspx?ID=87. Gas lights would perhaps melt ice better than incandescent bulbs?

    Peasant conservatism has to be overcome.

    Until something even better emerges.

    Bad technology and sloppy engineering should be replaced by better technology, not with retreating

  45. As the article said, the old incandescent bulbs would fail too. And not just during a heavy snow when folks know that they need to be cautious. Perhaps in the northern states the LED version could have a heat strip that would activate below a certain temperature. In the mean time, drivers that approach a stoplight protected intersection where neither red or green lights are visible should do as we did in the past when the incandescent bulbs failed. Be careful.
    .
    There are roundabouts in the states–not many yet. They seem to work very well. Folks assume the responsibility for not crashing into each other instead of blindly responding to red and green lights.

  46. Another thing: Why are most signals, lanterns, lighthouses and so on based on red/green? More than 5% of males and 0,25% of females have a red-green color vision defect. For example blue and yellow had worked for practically all people. Impaired blue vision is extremely unusual.

  47. Tom (06:16:45) :

    For once these are the unintended consequences of government doing something smart, than of government doing something stupid.

    The proof is in the pudding. It was not smart.

    Luke 7:35
    “Yet wisdom is vindicated by all her children.”

    Wisconsin of all places!

  48. As an engineer for a city in western Oregon (the wet part of the state), I heard about the snow buildup issue on the LED lights a few years ago in trade publications. Since we don’t get much blowing snow it doesn’t pose a big problem here. I remember thinking that the folks in Wisconson and Minnesota might want to do something different. The LEDs are certainly much better lights since they are brigher and more reliable. Adding heating elements and some sort of temperature sensor is possible, but will almost certainly drasticly increase the cost for each LED “bulb”.

    When the LED traffic signal bulbs start to fail, you will usually see a line or blotch of the individual LEDs “burned out” This is caused by a wiring fault somwhere in the LED bulb. The only fix to replace the entire bulb. I think some of that was the manufacturer’s learning curve since the problems took a few years to reveal themselves.

    As far as energy use in absolute terms for traffic signals, I have always heard that the annual power bill for a non-LED traffic signal was around $1,500. A 80-90% reduction could add up for large cities with lots of traffic signals. Of course using 80% less power doesn’t lower you bill by 80% because of the base service charge the power company charges for just having a meter.

    Also, the metal shields on the traffic signal lights are there to shade the lights from the sun for better visibility, not so much to direct the light forward (although it does help). Adding the curved plastic shield over the LED will keep the snow and ice off the LEDs, but I imagine that the plastic will get discollored over time, much like the headline covers on a used car, and make the lights appear less bright. I would also hate to have one fall off onto my car from 20 feet up.

  49. This is an example of how changes in operations usually result in changes in secondary effects.

    We do not live in a risk free society and every change you make in infrastructure leads to changes in risks.

    For example the introduction of antilock brakes and stability control systems for cars do not significantly reduce the number of accidents, it just changes the type of accidents people get into. Before the antilock brake people would slide off turns they could not slow down for and stuff the car into some ones fence. Now they safely slow down enough to get most of the way through the turn and roll the car as it goes off the road. In some conditions the antilock brakes actually increase stopping distances, resulting in cars sliding into intersections that they should have been able to stop for, or increased numbers of rear end collisions at intersections, because of overshoot. It is all a choice of evils.

    Here where I live, the law says if a stop light is not working or not visible, the intersection becomes a 4 way stop. The driver (if they recognize there is a blocked signal) should stop and look both ways before entering the intersection. That does not help much for the case where the driver does not recognize there is a signal and simply blows through the intersection, but the exact same failure can happen with the incandescent lights if they burn out, so this becomes pretty much a toss up.
    Traffic signs like stop signs are also subject to exactly the same “covered with snow” problem when you have a wet blowing snow and temps are cold enough that the snow sticks to the front of the signs. People manage to figure that out too.

    I have noticed here where I live that a good number of traffic lights no longer have the shades on them. Perhaps that is the reason.

    Like all new technology over time they will figure out work-arounds for these problems like removing the shades, and heaters of some sort.

    Larry

  50. The LEDs are probably a good idea because they reduce cost for electricity and maintenance. And they should be more reliable since a failure of 1 LED will not cause the light to go black. I think an engineered solution can be found through better design of the hood and lens. Some plastics like Teflon and polypropylene are naturally slippery and would be more resistant to the sticking snow problem. I wouldn’t give up on the LEDs.

  51. Most traffic signal LEDs are retrofits of existing traffic signal fixtures, and with the cost of energy today, these retrofits make a lot of sense economically. If the entire fixture had to be replaced, I’m afraid the economics would stop many of these changes.

    However, as Gail Combs (08:21:11) : noted,

    “If the current media crisis was “Oh my there is a coming Ice Age”, someone might have considered the icing up problem of these new lights and produced a decent, VALIDATED engineering design. Instead we have lights that will fail in snowstorms and bankrupt local governments who are not about to spend money to replace the new lights they just installed a few years ago.

    The cost? People injured and dead. That is not ““typical of the fear for all that’s not as it used to be. Father never used an LED.” That is concern for our fellow humans. Something the left/progressives/marxists or whatever politician is speaking is always proclaiming, but the reality of what they implement as law always seems to be far different.

    I’m sure a very smart engineer out there somewhere will develop a design that doesn’t allow snow to accumulate (or stick to the surface in the case of wind driven snow) and be cost-effective enough to allow the replacement of the older design fixture.

    Then the fight will be with the government agencies that will have to approve the new design!

  52. Sorry to be pedantic, but I think you’ve an extraneous apostrophe in the post title.

    ABC used it to denote the “Stoplights’ … Problem” which is correct, if annoyingly anthropomorphic. It is unnecessary in your headline.

    Also, it’s about -11F here; I’m attributing my grumpiness to that. Thanks!

    [Fixed, thanks’ ~dbs, mod.]

  53. I’ve noticed several LED stoplight conversions in New Hampshire over the past few years, but have never noticed a snowcovered lamp. Most of our windblown snow is cold and dry and won’t accumulate, I’m sure near the rain/snow line it could be a significant problem.

    So, solutions might include heaters to avoid temperatures around freezing and not heat below 25F or so. Changes to the light shade and covers could work well too.

    I’ve only seen failed strings in the green lamps, they do run at a higher voltage than red, but I’m not sure about their efficiency. Some of the high power 3W white LEDs that have popped up in the last few years are mounted on heat sinks, and the low power ones certainly generate heat. I bought a white LED Christmas tree light string on sale after the 2008 season (something like $0.10 per white LED, an awesome price) and mounted 50 LEDs on a piece of perf. board. The LEDs do get quite warm at the typical 20 ma current. LEDs are nowhere near 100% efficient, they’re just a lot better than incandescent lamps.

  54. Steve in SC (08:10:36) : “…Temperature sensors that would turn them on would burn a lot of useless electricity…”

    Wrong.

  55. I live in France where they still usually have incandescent bulbs in the traffic lights, as far as I know (sometime you can see fluorescent coils and they seem to be better). The problem here is the setting sun shining directly into them, as they are very weak. I always slow right down or stop in such a case – get hooted at by the car following but don’t budge until I’m sure.

  56. hotrod (08:59:10) : “…In some conditions the antilock brakes actually increase stopping distances…”

    You’ll have to prove that. Please provide a link.

  57. OT, but did anyone notice that Lake Okeechobee was ccalling Snow earlier? I’m sure it was a sensor issue due to the temperature at the time, but interesting nonetheless.

    KOBE 091129Z AUTO 35009KT 10SM SN SCT060 OVC095 05/03 A3014 RMK AO2
    KOBE 091109Z AUTO 35010KT 10SM -RA BKN060 OVC095 05/02 A3014 RMK AO2
    KOBE 091050Z AUTO 35010KT 10SM SN OVC060 06/03 A3013 RMK AO2

    The current estimated Lake temperature is 57F and the wind was blowing from the Northwest. The town is on the North end of the lake.

  58. Crashex (08:25:07) :

    News commentary and shows like 60 Minutes are usually presented from the perspective of the plaintiff’s lawyer.

    There is also a big problem with trial by jury. The jury is supposed to be 12 peers, or something along those lines. But what a jury really is is 12 people who weren’t smart enough to get out of jury duty.

    No wonder a lawyer who, in some cases, does little more than capture the attention of such a jury is able to win his case. Just presenting dry facts to a jury should be enough. It’s not. An entertaining presentation is needed.

    What a world, hey?

  59. Al Gore’s Holy Hologram (08:39:47) :

    Pray we do have some global warming. If cooling continues we’ll use more energy and have less energy security.

    We’ve got plenty of oil in Alaska. And plenty of coal in the Appalachians. Lots of other resources too. We just need to use them.

  60. Many serious accidents happen at traffic lights, because people speed up to get through at the end of a cycle. Roundabouts are much safer because you have to slow down entering a roundabout, and because there is no reason to rush. You never have to wait for a light to cycle.

    In England, many roundabouts are nothing more than a painted circle. Nothing expensive about that.

  61. jorgekafkazar (10:08:32) :

    hotrod (08:59:10) : “…In some conditions the antilock brakes actually increase stopping distances…”

    You’ll have to prove that. Please provide a link.

    refers to braking on dry pavement…
    onr such link

  62. Al Gore’s Holy Hologram (08:39:47) :
    Pray we do have some global warming. If cooling continues we’ll use more energy and have less energy security.

    Sorry, no.

    We are in more danger from self-styled elitists, pseudo-scientists and busy body intellectuals than we are from the climate.

    James 5:17
    Elijah was a man with a nature like ours, and he prayed earnestly that it would not rain, and it did not rain on the earth for three years and six months.

  63. Polar Bears Forced to Land and Water

    Holy smokes, the polar bears can, and are adapting, who would have ever guessed !??
    Makes me all fuzzy and warm and…

    As Arctic sea ice melts, polar bears are changing their habitat, shifting from their preferred ice hunting grounds to land and open water, according to a new long-term study.

  64. jorgekafkazar (10:08:32) :

    hotrod (08:59:10) : “…In some conditions the antilock brakes actually increase stopping distances…”

    You’ll have to prove that. Please provide a link.

    Road and Track did a test back in the late 80’s using a Mercedes with and without the anti-lock brakes. The results of the test were that for adverse conditions except on dry pavement the car stopped in a shorter distance by just locking up all four wheels. On glare ice locking up the wheels produced stopping distances three times less than the same car with the anti-lock enabled. They initially tried to modulate the brakes but they were thwarted by the wooden feel of the brakes through the anti-lock mechanism so they just locked the wheels up.

  65. Chris C. (08:57:15) :

    I hate to appear dense in asking, but are you trying to tell us something good or bad about these lights?

  66. This is an easy fix. Just install a temp actuated heat element behind the lights. Problem solved. I have them in my rear view mirrors on both sides of my car.

  67. I wouldn’t use a temperature sensor and a heater to fix the problem because that would just waste a lot of electricity in cold climates. 32F is t-shirt weather now. Ideally a change to the protective covers and surface of the lamp would resolve most of the problem passively. The best active approach seems to be some sort of emitter and a photodiode to catch the reflection if snow/ice have built up in the cowling or just a timer and a photodiode to see if there’s sufficient sunlight coming through at say, noon. If there isn’t, then turn on the heater and do some melting. Hmm, what DOES the patent office have to say on the issue…

    I can also say that here in Minnesota I personally haven’t seen any issues, but I believe the accounts.

  68. The simplest solution, IMHO – if the light needs to be shrouded, use a single shroud that arches over the topmost light, and goes down the sides of all three. This prevents side glare, and leaves no shelves for snow to collect in front of the lights.

    I haven’t read all of the comments, so I don’t know if I’m too late with this suggestion?

  69. All they have to do is seal the traffic light fixtures then pump them full of CO2. Then they will be snow free in the winter.

  70. As was already suggested their are solutions to this problem. LED lights are the way to go but in cases like these extra measures must be taken to create a safer environment. There’s no excuse by the relevant authorities for not taking these measures. They need to learn from their mistakes and act. If they don’t then they are culpable.

  71. starzmom (06:26:37) :
    “A small heating element in the light fixture, perhaps?”

    The law of unintended consequences strikes again. LED’s, being a solid state device, will be damaged by excessive heat. > 300 deg K will lead to their early failure, and > 375 deg K will destroy them in an hour. Heat is the mortal enemy of all semiconductors. Compare this to as high as 3,300 deg K for the tungsten filament of an incandescent light bulb. Since just slapping a heating element inside the LED traffic light an inch behind the polymeric cover will be an engineering failure, a viable defrosting system would have to be a clear cover with an imbedded filament heater, much like the design of the rear window defroster found on automobiles with a hatchback instead of a trunk. Such designs apply more heat to the outside surface of the glass than to the interior surface. The imbedded heater design would also rule out any polymers for the composition of the cover due to the intense spot heating that will occur nearest the heating filaments, so a tempered heat resistant glass cover would be required. In order to be effective, the heater would have to initiate automatically, triggered by an optical sensor that detects a decrease in light intensity a short distance in front of the clear cover. Then the engineer has to figure out a way to prevent the optical sensor itself from becoming snowbound. The sensor circuit would also have to “know” when the particular bank of LED’s are energized or not. Also needed is a temperature sensor to prevent false triggering due to rain, fog and dust. Oh the expense!
    Now, if someone would discover the formula for clear Teflon for which to make a cover, problem solved without heat! Until then, I think the best remedy is the retro solution, remove all red LED traffic lights in snow-prone areas, and reinstall the incandescent red light models.

  72. Schools still indoctrinating students on the global warming meme with the help of ABC.

    Ask you child when he or she comes home and preaches about Man-made global warming ad CO2, Are you a climate scientist? Can you show me the peer reviewd science? What, no to both questions? Then shut the hell up.

    Cold Can’t Shake Global Warming Faith of ABC’s Blakemore
    http://newsbusters.org/blogs/matthew-philbin/2010/01/08/cold-cant-shake-global-warming-faith-abcs-blakemore

  73. I’m not against the LED Traffic lights, in addition to energy savings and reduced maintenance costs, unlike regular lights, the LED have a graceful failure. That is they start to dim and some lights go out as the start to fail.

    HOWEVER like all engineering, some trade offs are needed.

    (1) The light needs to be open on the bottom, to drop any snow that might try to gather. (See link below.)

    (2) In some areas, heaters may be needed when temperatures drop below freezing.

    The problem is NOT unsolvable, it just takes more effore to make sure the system works properly.

    Also, STUPID drivers need to be trained, if we don’t see a light, STOP FIRST!!!!

  74. At last a BBC weatherman questions the computer models

    \\\ A frozen Britain turns the heat up on the Met office. ///

    http://www.bbc.co.uk/blogs/paulhudson/2010/01/a-frozen-britain-turns-the-hea.shtml

    Which begs other, rather important questions. Could the model, seemingly with an inability to predict colder seasons, have developed a warm bias, after such a long period of milder than average years? Experts I have spoken to tell me that this certainly is possible with such computer models. And if this is the case, what are the implications for the Hadley centre’s predictions for future global temperatures? Could they be affected by such a warm bias? If global temperatures were to fall in years to come would the computer model be capable of forecasting this?

  75. P Gosselin (06:53:02) :
    “For Americans, a roundabout is a so-called traffic circle.”

    Except in Boston. Beware the sign that says “Rotary Ahead.”

  76. A couple of small sections of nichrome wire run accoss the light that are turned on automatically would solve the problem Most traffic lights are run by a housing that has timers, etc. for how long the lights are on each direction and when they go on blink in the middle of the night. Adding a thermistor that turns on a heater to those would be a no brainer.

  77. Have a small heater in the traffic light that is controlled by the temperature. Below zero and it switches on, above and it switches off.

    This could be accomplished easily enough with a “hybrid” lamp. One that has both LEDs and an incandescent bulb. At a certain temperature, a bi-metal contact such as this(not exactly that device but one like it set for the proper temperature) would close causing the incandescent bulb to illuminate when the signal is active in addition to the LEDs. When the temperature rises above freezing, the bi-metal would open and the incandescent bulb(s) would no longer operate. The sensor could be mounted to the lens someplace near the edge with thermally conductive epoxy.

    As the incandescent bulb(s) would operate only when the lens temperature was below the activation temperature of the temperature sensor, they would last much longer and if they failed, would still continue operating with the LED lamps.

    Making a hybrid assembly with several smaller incandescent bulbs mixed in with the LED lamps is how I would approach the problem.

  78. I would just like to address all these “hey, stupid… STOP if you can’t see the light” comments.

    It’s one thing for a light to be out. People usually deal with this quite well.

    But a fixture covered with snow can blend right in with background and falling snow in much the same way that a camoflage wallet in the bushes is the most money you’ll ever lose until fall.

    It’s made all the worse when the people before you go through without anything happening to them or anyone else. No one sees the light fixture, let alone a light, so they see no reason to slow down. So why would you?

  79. Steve in SC (06:32:51) :

    “LEDs do emit heat, just not a whole lot.
    They are more efficient and thus produce the same light with less wattage dissipated in heat. They are substantially more visible in situations where glare is a problem. Which poison do you want?”

    I’ve never had a serious problem due to an encounter with an incandescent traffic light, yea there has been a few times where the sun was shining in my eyes and I had difficulty seeing the light, but I dealt with it. On the other hand, I’ve encountered a few overzealous LED traffic lights at night that absolutely blinded me, causing me to lose my “dark adapt”. It’s the same effect you get by staring at the sun or having someone shine a 10 megacandela spotlight in your eyes. I’ll take the red pill.

  80. West Palm Bch Intl Ap explains one red dot in Florida over the past two days. Now what about the other one from Thursday in the Pan Handle?

    January 7 and 8, 2010:

    http://mapcenter.hamweather.com/records/2day/us.html?c=maxtemp,mintemp,lowmax,highmin,snow

    86 F, previous record 82 F in 1998

    at this station

    Marianna Caa Ap, Fl

    I believe this is the station

    http://www.nc-climate.ncsu.edu/cronos/?station=085367

    Anyone live in Marianna, Florida?

  81. latitude (12:49:19) :

    Which is quite impossible, since places 10 miles away reported record lows.

    —————————————————————-

    Shesh! Unbelievable!

    UHI—it’s worse than we thought!

  82. photon

    considering that right above WPB,
    Stuart set a record low of 35F,
    and right below WPB,
    Ft Lauderdale set a record low of 36F.

    And they want anyone to believe that 20 miles inbetween
    those two record lows, 35F and 36F,
    it was 88F.

    In Florida, with the wind blowing

  83. If co2 makes it warmer,
    why is dry ice so damn cold ?

    { Hank Hancock (11:37:09) :

    All they have to do is seal the traffic light fixtures then pump them full of CO2. Then they will be snow free in the winter.}

    At 100% co2 you risk Venus air temps…
    You’ll melt more than just the snow…
    “Goodness, gracious, great bulbs of fire !!!”

    On that theme, just fill multi-pane windows with co2 between the glass. A little sunlight on the window will create runaway temperatures like on Venus, high enough to heat our homes, or cook a roast… throw another shrimp on the window sill for me, would ya?

  84. I’d say that roundabouts in the UK have been successful, by and large. I think we have always had more of them than other comparable countries. They come in all sizes, e.g. mini-roundabouts (which some people admittedly detest, but I like).

    I think that provided drivers treat them in the spirit intended, they can work very well. As someone else has said, on the larger, busier roundabouts, they have installed traffic lights, which kind of defeats the purpose. IMHO, traffic lights “deskill” the driver, who tends to just look at/for the lights, and not at what’s on the road.

    Sadly also, traffic lights generally do seem to be making a bit of a comeback here. In my town (which used to be relatively traffic-light free), they introduced a big new traffic scheme, supposed to tackle congestion, heavily dependent on linked traffic-lights. Needless to say it increased congestion…

  85. hotrod (08:59:10) : “…In some conditions the antilock brakes actually increase stopping distances…”

    You’ll have to prove that. Please provide a link.

    Antilock brake system will not stop you as fast as locked up wheels in loose gravel and deep snow.

    There are also warnings in published materials that in some conditions they lengthen stopping distances at the trade off of maintaining steering control.

    The Subaru WRX had over sensitive antilock brake design in the early models that resulted in a recall for reprogramming. Some users including myself experienced near total brake failure due to the defect in certain conditions, where the computer would misinterpret wheel lock signals when crossing rail road tracks, manhole covers, and small patches of sand on pavement. This is due to the split traction problem where one wheel is on a very slippery surface but all other wheels are on high traction surfaces. Some ABS systems will interpret the wheel lockup on the wheel with low traction as an indication that all wheels are on low traction surface and lower braking effort to suit the lowest common denominator wheel. The result is that all 4 wheels braking effort is reduced so they would not lock on that slick surface greatly increasing stopping distance. This problem resulted in a “consumer satisfaction” recall by Subaru where you could have the ABS computer reprogrammed to reduce the problem. Most found the better solution was to remove the electrical fuse for the ABS system and go back to predictable brake performance of a mechanical hydraulic system that did not try to out think the driver.
    With the ABS shut off the car had much higher braking effort and did not at random refuse to decelerate at traction limited rates.

    http://www.abs-education.org/faqs/faqindex.htm

    In what circumstances might conventional brakes have an advantage over ABS? There are some conditions where stopping distance may be shorter without ABS. For example, in cases where the road is covered with loose gravel or freshly fallen snow, the locked wheels of a non-ABS car build up a wedge of gravel or snow, which can contribute to a shortening of the braking distance.

    http://www.iihs.org/research/qanda/antilock.html <— see item #3

    http://www.nhtsa.dot.gov/cars/rules/regrev/evaluate/808206.html

    # All types of run-off-road crashes – rollovers, side impacts with fixed objects and frontal impacts with fixed objects – increased significantly with ABS. Nonfatal run-off-road crashes increased by an estimated 19 percent, and fatal crashes by 28 percent.

    # Rollovers and side impacts with fixed objects – crashes that typically follow a complete loss of directional control – had the highest increases with ABS. Nonfatal crashes increased by 28 percent, and fatal crashes by 40 percent.

    # Frontal impacts with fixed objects, where the driver is more likely to have retained at least some directional control prior to impact, increased by about 15-20 percent, both nonfatal and fatal.

    # The negative effects of ABS on run-off-road crashes were about the same under wet and dry road conditions.

    # The observed effects of ABS on snowy or icy roads, while not statistically significant, were all similar to the effects on wet roads – i.e., positive for multivehicle collisions, negative for run-off-road crashes.

    # The overall, net effect of ABS on police-reported crashes (including multivehicle, pedestrian and run-off-road crashes) was close to zero.

    # The overall, net effect of ABS on fatal crashes was close to zero.

    http://www.thetruthaboutcars.com/nhtsa-abs-braking-increases-fatal-run-off-road-crashes-by-34/

    http://www.harristechnical.com/articles/abs.pdf

    Larry


  86. mikelorrey (06:56:59) :


    According to this: http://www.cee1.org/eval/db_pdf_es/275es.pdf
    22% of US electric consumption is in lighting. Converting to LED lighting nationwide for everything would therefore reduce consumption overall by 20%.
    /

    Incorrect conclusion; false economy; straight-line projection failing to take into consideration other factors.

    It assumes, perhaps, that the waste heat produced does no one any good, but let me say, with the outside temperature at 25 deg F today this is _not_ waste heat (as I heat with ‘clean’ electric as do many others in my ‘planned’ subdivision do).

    .
    .

    • Jim
      2010/01/09 at 1:39pm

      mikelorrey (06:56:59) : …
      According to this: http://www.cee1.org/eval/db_pdf_es/275es.pdf
      22% of US electric consumption is in lighting. Converting to LED lighting nationwide for everything would therefore reduce consumption overall by 20%.
      /

      “Incorrect conclusion; false economy; straight-line projection failing to take into consideration other factors.

      It assumes, perhaps, that the waste heat produced does no one any good, but let me say, with the outside temperature at 25 deg F today this is _not_ waste heat (as I heat with ‘clean’ electric as do many others in my ‘planned’ subdivision do).”

      While I agree that waste heat produced in WINTER is useful (albeit that lighting is an inefficient heater), waste heat in SUMMER is quite the opposite and increase power consumption in air conditioning loads, so averaging annually, and considering that it is easier and requires less energy to heat than to cool, that its still to a benefit to use efficient lighting technologies like LEDs.

      While traffic lights like these might need the heat for a few hours when being pummelled by wind blown snow, this accounts for less than 1% of the operational time of the light so its still a waste to have it generating heat 24/7 in winter. At best, I’d recommend that the bezel in front of the LED panel utilize a small heating element that utilizes a capacative sensor that senses when there is appreciable bulk water in front of the light.


  87. toyotawhizguy (11:56:49) :

    starzmom (06:26:37) :
    “A small heating element in the light fixture, perhaps?”

    The law of unintended consequences strikes again. LED’s, being a solid state device, will …

    A case of retrofitting an old physical traffic control light design with a new ‘bulb’/illumination device without considering other factors, like, the old designs factored-in the melting of snow/ice via incandescent bulb heat …

    .
    .

  88. Gail Combs (08:21:11) :

    What does this illustrate? Sloppy engineering.

    If the current media crisis was “Oh my there is a coming Ice Age”, someone might have considered the icing up problem of these new lights and produced a decent, VALIDATED engineering design.

    Au contraire; this was a decision by some bean counter to save beans. A retrofit of existing traffic control lights to an illumination/light source which promised to save money in replacement work and in power consumption.

    I don’t think the city did a speck of ‘engineering’ with regard to suitability in the variety of weather types experienced in a northern climate.

    .
    .

  89. latitude (13:05:09) :

    The 35 and 36 were nighttime lows (look at color ledger at the top of the map) and the 88 was a daytime high. But still I understand your point. The heat sources at the airport made an inaccurate temp reading. It wasn’t 88 yesterday in West Palm Beach, only at the airport.


  90. mikelorrey (13:49:45) :
    ..
    While I agree that waste heat produced in WINTER is useful (albeit that lighting is an inefficient heater), waste heat in SUMMER is quite the opposite and increase ..

    Still doesn’t get you close to “20% savings” figure cited.

    .

    • Jim
      2010/01/09 at 1:55pm

      mikelorrey (13:49:45) :
      ..
      While I agree that waste heat produced in WINTER is useful (albeit that lighting is an inefficient heater), waste heat in SUMMER is quite the opposite and increase ..

      “Still doesn’t get you close to “20% savings” figure cited.”

      .Actually, given the reduction in air conditioning load in summer will be greater than the increased demand for heating in the winter, the savings should wind up being greater than 20%.

  91. Philip T. Downman (08:53:33) :

    Another thing: Why are most signals, lanterns, lighthouses and so on based on red/green? More than 5% of males and 0,25% of females have a red-green color vision defect. For example blue and yellow had worked for practically all people. Impaired blue vision is extremely unusual.

    It’s all about the sensitivity of the rods and cones in your eye. The eye is extreamly sensitive to red, for example. Glance around a room and you notice the red thing straight away. Green is the same: you’ll notice a green thing much quicker than, say, a blue thing.

    It’s an evolutionary construct. Back when proto-humans were running around the African Savanna, you essentially had a big green jungle and a bigger blue sky. Small changes in the sky don’t mean much, so you don’t see them. If you saw a flash of red or anything else close to the wavelength of red (eg. yellow), you need to register that instantly, because it is probably dangerous.

    The same goes for changes in green: different plants mean different things.

    So, red/green is where it’s at.

    I don’t know about the US, but here in Australia our traffic lights are all arranged vertically, with red at the top and green at the bottom, so colour registration is supplimented by position. Lose colour, and you can still see what the lights are saying.

    When I was in Japan, though, I noticed that some lights were arranged horizontally. I’m sure there was a consistenancy there, too, but it does require a level of interpretation that the Aussie system removes.

  92. mikelorrey (13:49:45) :
    While I agree that waste heat produced in WINTER is useful (albeit that lighting is an inefficient heater), waste heat in SUMMER is quite the opposite and increase power consumption in air conditioning loads, so averaging annually, and considering that it is easier and requires less energy to heat than to cool, that its still to a benefit to use efficient lighting technologies like LEDs.

    This is entirely dependent on location. Alaska, for example, has very few “hot” days… In California near the coast, when it is hot during the day, it often becomes cool at night; when you need both heat and light. In Phoenix, yeah, pretty much LEDs win all the time. In frozen high mountains, not so much…

    And that is why any decision on what lightbulb to use ought to be left firmly in the hands of the customer doing the buying and using.

    “One size fits all” doesn’t.

    (Not mention I don’t want mercury in my fridge so the CFL bulb is a really dumb idea and I don’t want to put a gazillion hour $40 LED light in a basement closet that MIGHT get used 1 hour a year, maybe. Oh, and the various chick hatchery, cat warmer, lizard warmer, etc. “heat and light” choices. Not to mention that the $12+ CFL “dimmable” bulbs are not smoothly dimmable and have more of a “step function”… And did I mention that they give some migraine sufferers headaches? I know one such person. Then there is the fact that you get 10,000 on/off cycles as a limit – not just years – so things like motion sensor yard lights are going to be dropping like flies if near any foot trafic [and any other place with frequent on/off cycling like fridge, bathroom, kitchen…] . And then there is the “time to repair” issue. At the mechanic yesterday a guy came in with a brake light that would flicker on once, then off. Instead of a 2 minute “change bulb” (it being LED not bulb) for a couple of bucks he was told “It has a card with electronics on it, bring it back Monday and we will put it on the analyser” …)

    Individuals need to make choices, not governments with “one size fits all” prescriptions that don’t.


    While traffic lights like these might need the heat for a few hours when being pummelled by wind blown snow, this accounts for less than 1% of the operational time of the light so its still a waste to have it generating heat 24/7 in winter. At best, I’d recommend that the bezel in front of the LED panel utilize a small heating element that utilizes a capacative sensor that senses when there is appreciable bulk water in front of the light.

    Seems pretty complicated to me. Why not just put a clear plastic snap on cover over the front of the ‘can’ and not let the snow in in the first place? Easy retrofit too. (The “can” is there to control who can see the light, but seems to me there is no reason not to move the “bezel” to the front on new designs.)

    • E.M.Smith
      2010/01/09 at 2:10pm

      “This is entirely dependent on location. Alaska, for example, has very few “hot” days… In California near the coast, when it is hot during the day, it often comes cool at night when you need both heat and light. In Phoenix, yeah, pretty much LEDs win all the time. In frozen high mountains, not so much…

      Individuals need to make choices, not governments with “one size fits all” prescriptions that don’t.”

      “Seems pretty complicated to me. Why not just put a clear plastic snap on cover over the front of the ‘can’ and not let the snow in in the first place? Easy retrofit too. (The “can” is there to control who can see the light, but seems to me there is no reason not to move the “bezel” to the front on new designs.)”

      I agree 100%. My conclusions are based on overall averages of the nationwide installation base of lighting. Having worked as a professional lighting designer and energy analyst (featured on a Washington Post cover story), I’m quite aware of the complexities of the issue and the broad range of individual siting requirements.

      While lighting does also heat a building, usually that heat is in a place where it is not able to be used effectively. It typically winds up radiating upward from ceiling or wall installations into crawlspaces and is never used for warming the working spaces of a building.

      In the specific case of these traffic lights, its clear that incandescent traffic lights utilized the heat to keep the lenses clear of snow on the rare occasions when that risk existed (even in Alaska), but as another reader here pointed to a shroud that uses louvers to create wind vortexes inside the shroud to keep the lens clear of snow, it is entirely possible to solve the engineering problem without consuming energy… This is smart design and demonstrates that sticking with the way we’ve always done it isn’t the most effective thing when implementing new technologies.

  93. 22% of US electric consumption is in lighting. Converting to LED lighting nationwide for everything would therefore reduce consumption overall by 20%.

    I think there are some false assumptions in that. First, it must assume that all current lighting is incandescent. It isn’t. Most commercial buildings are already lit with non-incandescent lighting and many homes already have fluorescent lighting in places like the garage and possibly the kitchen. Switching to incandescent of what might amount to 10% of the 22% of the US electricity consumption would then reduce consumption overall by an amount barely measurable in the total electric consumption scheme and, as another commenter noted, result in simply shifting of some energy to other sources when the primary climate control is heating. You can consider incandescent lighting to be dual purpose in winter where they provide both light and heat.

    The idiotic CFL craze is fed by people wanting to feel like they are “doing something” to “save the planet” when they are actually doing nothing at all and the planet might not need “saving”. It is an emotional “lotion” to mollify people’s anxiety and doesn’t *really* do anything about energy consumption.

    Switching to CFLs at my office, for example, would save exactly NOTHING since all lighting is already fluorescent anyway.

    • crosspatch (2:29pm):
      “Switching to CFLs at my office, for example, would save exactly NOTHING since all lighting is already fluorescent anyway.”

      If CFLs were the only most efficient alternative, you would be right. However, you aren’t. Fluorescent technology saves about 50% over incandescent technology. LED saves 80-90% over incandescent technology, therefore it saves 60-80% over fluorescent technology. For a given capital investment, you get the same return on investment to upgrade to LED from Fluorescent as you do to go from incandescent to fluorescent. And this is just in the energy savings. It turns out that the labor savings of LEDs over incandescent is about 95%, with an 90% savings over fluorescent in maintenance man hours and labor dollars. This makes the return on investment to upgrade to LED even greater from fluorescent, than from incandescent to fluorescent.

  94. One thing I would suggest is that all new building use DC lighting. Every building would have a 48 volt AC feed which would be rectified to DC at the building entrance. This would allow people to add PV or wind turbine energy to the system much more easily. It would also allow battery backup at the premises. In case of power shortages, the 48VAC circuit could be shut down first. This circuit would provide power for such things as lighting, a new style of “wall warts”, etc. Various appliances would still be powered by the conventional 110 or 220 volt feeds. You could then do a different sort of “brownout” where you shut off the 48vac feed and reduce energy demand from the utility and that shuts off only people’s lighting (except maybe for an emergency lamp) but leaves their freezer and any required life support systems working. Homes that elected to install a battery backup and possibly have local PV or wind capacity might not even notice the disruption at all.

    • crosspatch
      2010/01/09 at 2:37pm

      “One thing I would suggest is that all new building use DC lighting. ”

      Meh, not terribly smart. Going from 240v AC to 48v DC (or from 120vAC) requires all the wiring in the building to be changed, as lower voltage requires greater amperage for the same wattage. Forex, 120vac to 48vdc requires the guage of the wire to be three times greater. This would be a boon for the copper industry, as the price of copper would skyrocket, and wiring anyplace would become insanely expensive.

  95. Until they can make a white LED that doesn’t suck, LED lighting is not an option for me. The color is not white and it gives me a headache.

  96. I think it likely that having had the issue brought home to them, the traffic light design engineers of the world will come up with a relatively easy and ingenious design change for the future.

  97. Let me try that again:

    The easy fix is to not have the shield that collects the snow, especially since LED’s shine brighter and don’t need to have the light directed.

    An easier fix would be the addition of a ceramic (or similar) type heater that modulates its heat output according to the surrounding temperature. Solid state. Low tech (at the point of application).

  98. Meh, dont need the heat ALL the time in the winter, Simon, you just need it when water is present. That says you need a capacitance sensor.

  99. but as another reader here pointed to a shroud that uses louvers to create wind vortexes inside the shroud to keep the lens clear of snow, it is entirely possible to solve the engineering problem without consuming energy…

    If you don’t count the cost of replacing the traffic light fixtures or the cost of modifying them in the city/county where they are installed.

  100. Meh, dont need the heat ALL the time in the winter, Simon, you just need it when water is present. That says you need a capacitance sensor.

    Then you have the problem of sensor reliability and the reliability of power control electronics. And water is not the problem. Snow/ice is the problem. Why turn the heat on in a rainstorm?

    Engineering wise I think it is worth a few extra watts in winter to reduce the risk of killing people.

    I’m of the KISS school of engineering. Aerospace division.

  101. And they want anyone to believe that 20 miles in between
    those two record lows, 35F and 36F, it was 88F.

    Not to worry. After homogenizing, the temperature record will show that Florida was a comfy 75°F.

    Anyone else notice that WordPress now has a built-in spell checker?
    (And it just underlined “WordPress”)

  102. @ Neil O’Rourke (14:06:59) :

    In Japan all traffic lights are arranged horizontally, green on the left en red on the right. Yet the lights for pedestrians are arranged in the usual vertical configuration. Although there green is often a bit on the blue-side.

  103. Everyone that is posting about having a different shield – the problem is driving, wet, sticky snow, that will stick to pretty much everything and anything.

    To me the obvious solution is to put at least one small halogen light in with the LEDS – enough to provide enough heat to warm the glass and stop snow sticking, or not use LEDs altogether. Or just go back to halogens in snow prone areas. There’s no cost savings in LEDS if you have to send out crews to clean the snow off – human hours and vehicle hours are much, much more expensive than electricity. I’m sure if someone did a study, they’d find it would only be a handful of maintenance trips to clean snow before the LED cost savings were lost. That’s before you even factor in the cost of a single fatal accident due to snowed over lights. In heavy snow, it’s not easy to see anything, let alone a traffic light with no lights on.

    The suggestions to incorporate a heating element are probably a good idea, but then you’d have to look at the total cost of ownership. The LEDs are doubtless already more expensive to install, adding electronics and a heating element would increase the cost further. And if an expensive LED set gets wiped out in a traffic accident and has to be replaced, does that further negate the cost savings?

    Someone needs to do an engineering study and work this out properly, taking into consideration all costs, including installation, maintenance, electricity usage and unexpected occurences like snow and accident damage.

    If a study was done like this (and ignored the ’emissions’ side), then a decision could be made with data rather than emotions. Even if you believe in the emissions problems, then the local authorities could plant a tree for each light they installed.

  104. Meh, not terribly smart. Going from 240v AC to 48v DC (or from 120vAC) requires all the wiring in the building to be changed,

    I thought I suggested it for NEW construction, not retrofitting existing buildings. New buildings would have a 48VAC feed and it would be only for low current applications such as lighting much like an RV circuit. I think having a separate low-current feed that can be locally backed up / augmented is a good idea.

    I would want one.

    • crosspatch (3:10pm): I thought I suggested it for NEW construction, not retrofitting existing buildings.

      So you did. Even so, the mass of copper in wiring is going to be triple (if the grid AC is 120v, sextuple if 240v), so your wiring cost is going to cost at least three times as much. If 48v homes becomes required by code, then the cost of copper is going to go through the roof and you could wind up paying ten times the current price or more to wire your building. Very inefficient and (at risk of sounding green) nonsustainable.

  105. crosspatch (14:37:56) :

    One thing I would suggest is that all new building use DC lighting. Every building would have a 48 volt AC feed which would be rectified to DC at the building entrance.

    A 48 VAC feed into the building? That seems incredibly wasteful in wiring and gauge. Industrial buildings almost always have their own transformer and could make their own. If you just want a full-wave rectified DC output, then you have a suite of other problems. If you want conditioned DC, then you may not want to start with 48 VAC, as the extremes are 48 x sqrt(2), or 68. An efficient switching power supply makes more sense.

    If the building has 3 phase power, then simple rectification would get a pretty decent DC.

    ——

    mikelorrey (13:49:45) :

    While I agree that waste heat produced in WINTER is useful (albeit that lighting is an inefficient heater),

    Incandescent lights are 100% efficient heat sources as long as the light (a small fraction of energy used) is kept inside.

    Not as efficient as heat pumps which are > 100% efficient and the heat from lighting may not go where you want it.

  106. latitude (14:12:11) :

    photon, the high was 73.3F at Palm Beach Gardens yesterday

    I was hoping Anthony would pick up on our exchange and make this red dot in record cold Florida in to a post. It does show vividly the UHI problem. Everyone in America knows about the cold in Florida. For people to find out that there was record heat at an airport in Florida would make the UHI case crystal clear to laymen.

  107. Why is no one talking about infrared LED’s? We use them in TV remotes. Make the traffic light lens from a material that is not transparent to IR, but will absorb it and heat up. On the cheap you could incorporate the IR LED’s with the others in a single-unit replacement for an incandescent or older LED bulb, use a bi-metal temperature switch, suitably set, for “just in case” heating. Otherwise an IR LED unit could keep the heating at the lens, where you want it, and away from the LED’s. Then you can switch on the IR unit however you want.

    Are all the available IR LED’s so weak they cannot be used this way for heating?

    • kadaka
      2010/01/09 at 3:41pm

      “Are all the available IR LED’s so weak they cannot be used this way for heating?”

      AFAIK, wrong part of the IR spectrum. You need an LED whose emission curve correlates with that of H2O’s absorption spectrum.

  108. There’e the right way, the wrong way, and the government way.
    Thanks to the last Energy bill, we get LED’s for traffic lights, CFL’s for home use, and nobody even notices the biggest waste, the Street Light.
    The LED’s should be in the Street Lights and your home, and either the CFL or incandescent in the Traffic Lights.
    LED’s don’t belong in icy weather Traffic Lights and CFL’s don’t belong in your home, and what the heck was Boxer thinking with when handing over our Big 3 electrical industries to China? I know who she wasn’t thinking of at the time… the public good.
    LED’s sold separately.

  109. mikelorrey (15:43:37) :

    AFAIK, wrong part of the IR spectrum. You need an LED whose emission curve correlates with that of H2O’s absorption spectrum.

    Say what? The lens material would be absorbing the IR emissions, converting them to heat, and that heat would melt off the ice and snow. The IR absorption spectrum of water does not matter for that.

    Oh, and it could also be an optically transparent coating on the lens that is absorbing the IR, instead of the lens material itself.

  110. Hmmm so people wanted to go green and so you end up with LED lights. But wait, they don’t generate enough heat to melt snow, solution?? big PLASTIC shields, oh the irony, to go green, they need to use an evil fossil fuel to do it, typical of the greens/left. Do as I say not as I do.

    And lastly in that video, that reporter goes on to say even the old incandescent lights had a similar problem, the yellow lights weren’t on as much so didn’t heat up, but it’s sitting between two heat sources red and green, so I’m sure that hardly ever happened if at all!

  111. Just imagine if this was the other way round and all these towns had installed regular lights resulting in dozens of accidents and a few deaths. We would hear about it non-stop from the MSM.

  112. Hmm. Reminds me of an incident I heard about years ago of a train crash in the U.S. Two trains were heading for a junction point. One of them didn’t get the signal that they were supposed to stop to let the other pass, and they crashed. There was a legal case about this, and what was ultimately discovered was that one of the drivers missed the stop signal, which was placed long before the junction, because a reflective material had built up in it (perhaps because of a leak in the signal allowing moisture to enter), which at certain times of day appeared to show a green light, even though the bulb for that light was not powered on. Tragic case.

  113. latitude (14:12:11) :

    I just saw on The Weather Channel that there was a few snow flakes in the air at a beach just south of West Palm Beach.

  114. photon without a Higgs (16:48:32) :

    latitude (14:12:11) :

    they just said a snow and sleet near Miami too

  115. “photon without a Higgs (15:33:45) :

    latitude (14:12:11) :

    photon, the high was 73.3F at Palm Beach Gardens yesterday

    […]
    For people to find out that there was record heat at an airport in Florida would make the UHI case crystal clear to laymen.”

    Did they place the thermometer behind the place where they test jet engines after maintenance work?

  116. “Someone needs to do an engineering study and work this out properly, taking into consideration all costs, including installation, maintenance, electricity usage and unexpected occurences like snow and accident damage.”

    I worked in the traffic industry, specifically designing traffic light controllers. Of course an engineering study was done, and LEDs came out on top. The decision had nothing to do with power or going green, but pure economics.

    LED lights cost more upfront, but due to their long lifetime the maintenance costs are much lower than incandescent. Imagine the cost of sending a crew out to replace a bulb every few years, having to hire traffic controllers, block off a lane, etc. Minimising having to work on the road is a significant factor in choosing to adopt many new traffic technologies.

    The other main benefits of LED lights are consistent colour and high intensity. Power savings are low down on the list… As one poster pointed out none of the street lights are LEDs.

    The idea that this is some green conspiracy is idiotic. It would be trivial to include a heating element in the lights and I’m sure some enterprising company is doing that right now.

  117. Neil O’Rourke (14:06:59) :


    It’s all about the sensitivity of the rods and cones in your eye. The eye is extreamly sensitive to red, for example. Glance around a room and you notice the red thing straight away. Green is the same: you’ll notice a green thing much quicker than, say, a blue thing.

    That is only true for people with normal color vision. Among Caucasian males (north european) Red Green color blindness (actually atypical perception not blindness), is almost 10% . To add complications there are several types and no tow have the same degree of red green colorblindness. I am one of those 10%. In good light with large color samples I can easily tell most colors apart, and identify them by name. In dim light, or with very small color samples (like thin lines on a chart) it is usually hopeless. I cannot tell dark purple from black or dark red or dark brown from dark green, or yellow from light greens.

    When I was in search and rescue, they would flag trails with red survey ribbon, by tying it on evergreen trees. I would walk right past the flagged tree and never notice the several inches long red ribbon. When I was told the tree was flagged I would have to visually search the tree to find the red flagging even when I knew it was there.

    For me, dark green and dark brown are indistinguishable in poor lighting, Dark red might as well be black or dark gray under the same conditions. Light green and white (in the form of lights) are indistinguishable unless they have significant gray tone differences or distinct color casts of another color.

    I was 14 or 15 before I realized that the “green light” on a traffic light was actually green, I thought it was simply a figure of speech, I always thought it was just a dirty lens on a white light. The new LED traffic lights are actually easier for me to tell the difference between the amber and the green lights. The older incandescent lights had a warm green color which was hard to tell from pale amber lights. The newer LED green lights tend to be more of a blue-green color and the amber has much higher color saturation, making it much easier to tell the difference between the two.

    On numerous occasions I have nearly blown through a traffic light that I did not even know was there, because the green or amber light blended in with city lights behind it and I did not even realize I was entering an intersection until the light changed to red. This is especially a problem when the background has lots of different types of lights like sodium vapor, mercury vapor, plain incandescent, and colored signs.

    In locations where cities and towns do not follow conventional placement of lights (in Colorado it is Green top, amber middle, red bottom) I cannot use physical location of the light to help tell if it is an amber or green light.

    Orange traffic cones for me, if dirty, are almost invisible if placed where their visual background is a dirt embankment or a green of similar gray tone.

    Do not assume your visual impact of colors is typical of others. It is most certainly not.

    In the case of folks who like to make color coded charts on the web, about 50% of the time, I cannot tell what the chart is saying without the use of colorblind tools to help me distinguish the colors of the chart traces. In some cases I literally cannot see some of the traces even if I know they are there because they totally merge with poorly chosen background colors. Light cyan and an off white background simply merge I will not even know the cyan trace exists unless you point it out to me.

    Normal color vision has highest sensitivity in the yellow green peak of the suns spectrum (high visibility chartreuse yellow used by emergency signs and fire engines in some places), not in red.

    If you place a dark blood red object on a dark background I will not even know it is there until I trip on it if the light level is low.

    Since some industries require normal color vision, people like me with red green color blindness tend to concentrate in other industries. I used to work in a computer data center on a crew of 4, ( 3 men one woman). All three of the men on the crew were red/green color blind. When we needed to know if a warning light was green or yellow we had to ask the woman to verify it. Or (Thank you Sun Microsystems ) use command line instructions to determine the warning light status.

    If you use color coding in warning lights or charts, include physical cues like location or line patterns on charts to give the 10% of your audience who cannot determine what you are trying to communicate by color alone a clue. Also make damn sure your color key has exactly the same color triplet as the line on the chart.

    Nothing irritates me more than someone who has a chart with two traces that are almost identical to me (say a yellow and light green) and when you use a color picker tool to compare them, you find out that neither trace has the same color triplet as the color key blocks on the chart.

    /end rant ;)

    Larry

  118. photon without a Higgs (16:52:54) :

    they just said a snow and sleet near Miami too

    Gore Brand Global Warming:
    Directions – Wind up model, mix with one part hot air and broadcast over affected area. Comes with a Money Down the Tubes guarantee.
    Warning: Avoid contact with populated areas. Keep out of reach of Politicians and Children.

  119. {… DirkH (17:01:35) :

    “photon without a Higgs (15:33:45) :
    latitude (14:12:11) :
    photon, the high was 73.3F at Palm Beach Gardens yesterday

    […]
    For people to find out that there was record heat at an airport in Florida would make the UHI case crystal clear to laymen.”

    Did they place the thermometer behind the place where they test jet engines after maintenance work? …}

    No, space is precious, they mounted it on top of the Honey Bucket Holding Tank Digester. That’s a “green” location…. bio-degradation you know…

  120. I agree with the idea to install a temperature triggered heater element.

    It wouldn’t be very difficult, all that’s required are some power resistors, a transistor and the right type of thermistor. Pick the thermistor type so that the resistors are switched one as the outside temperature falls below freezing and it will regulate power through the resistors to keep the assembly above freezing temperature. During summer it will consume virtually no power.

    The problem is that they didn’t think of this until it became a major issue.

  121. Heating element can be laminated into the “lens” and operated via thermostat as well as back-reflective sensing (you can use an LED for that as well). The back-reflective sensing measures the reflection off the inside of the lens, and when it’s ALSO sufficiently cold, one could operate the de-icing element on the lens. The element need only be a line; it doesn’t have to de-ice all the surface.

    One can’t rely on wind or gravity to get rid of any stuff that’s stuck on the lens.

    BTW: If it’s not cold enough for ice/snow (typically above 4 degrees C), then excessive back-reflection may indicate a fouled lens; which, if the signals are network, could be used to schedule a cleaning crew visit. Keep in mind though that the reflective sensor probably also responds to low sun angles where Murphy’s Law operates. If the sun is not intense, then one can discern the signal’s LED pulses from the “constant” sunlight.

  122. The LEDs are doubtless already more expensive to install, adding electronics and a heating element would increase the cost further.

    There are ways to do it that require NO electronics. You use material properties (positive temperature coefficient of resistance) to do the job. Then you only have the cost of the material and extra wiring to deal with. Reliability is very high.

    And as some one pointed out above, labor (and the attendant vehicle etc.) is the main cost in traffic light maintenance. So LEDs are a good thing.

  123. mikelorrey (15:01:32) :

    Me too. The capacitance of liquid water is going to be different from snow.

    But then your sensor has to be out in the elements. Not good for sensor life.

    Unless you have designed sensor based eqpt. you have absolutely no idea how difficult it can be. Murphy is very unforgiving. KISS.

    And how different is the capacitance of wet snow from liquid water? What factors would confound that differential? What happens when the sensor is covered with mud, or dirt. Or in a harsh industrial environment (say near a steel mill) metal particles.

    Murphy is a bastich.

  124. Suggestion: Incorporate radioactive elements to melt the snow and ice.

    “Better Living Through Thermonuclear Biochemistry”

    Did I miss any toes? ;)

  125. Somehow the conservation alarmists never seem to look for unintended consequencies of their wacky ideas. A good example are energy saving florescence light bulbs. My experience is that at given power rating, the light is several lumens lower than an incandesent light bulb with the same power rating. However the next jump is not small, ie 60 watts to 75 watts. If you want the same brightness, you have to buy a bulb with a higher watts rating. In addition, we will now be contaminating our land fills with toxic particles that contain mercury. The LED is yet another example of not asking what could go wrong? Of course, every example in top ten wacky ideas to save the planet fail to mention any limitations to the climate saving fiascos.

  126. M. Simon (20:08:27) : And how different is the capacitance of wet snow from liquid water? What factors would confound that differential?

    Out here in Kaleeforneeya (as Ahnold says it ;-) we have the occasional pigeon that likes to make a nest in the lights. It is said they like the high safe place AND the warmth. It would be interesting to find out if there are fewer “nesting” issues with the LED lights. But if you put in “warming” equipment, especially if it senses birds, you might find a whole new set of problems coming home to roost 8-}

    In my informal observations, they seem to prefer red to green (but not by a lot) and I’ve never seen one in the yellow.

  127. I’m quite pleased to see so many responses in this thread focused on improving the technology to address the problem rather than throwing the baby out with the ice-water so to speak. The most common suggestion by far seems to be incorporating additional heating elements that can be controlled when the temperature drops with many people wondering how that would effect energy consumption. So for fun some back of the envelope calculations yields:

    It takes about 1W to melt a block of ice weighing 0.01kg . 1 mm of water over a surface of 1 square meter weighs approximately 1kg. Ice weighs just slightly less then that and snow would be reduced by a factor of 10. The radius of a standard traffic signal lens is 0.152 meters giving an area of 0.0725 sq meters. So 1 mm of ice covering the lens would be just less than 0.0725 kg. We would then need about 7.25W to be able to melt that. If the buildup is primarily due to snow the energy required to melt that is an order of magnitude less due to the air content of snow and we could melt 10mm of snow for the same amount of power. 10 mm works out to just under half an inch. So 1″ of snow takes around 15W. For a single traffic light that is 45W for all three indicators. At each 4 way intersection you would need at least 4 signals or 180W. Add in turn signals that only require an amber/green indicator with the shared red lamp and you’ve just added an extra 120W which brings us up to 300W for a typical intersection on a 2 lane road.

    So doing a quick google search for applicable power rates for public utility lighting in a state that receives lots of snow/ice (Grand Rapids, Minnesota) gives us a rate of $0.0272 per kWh. 3 intersections would be able to run heaters continuously for an extra 2.72 cents an hour or 65.28 cents per day.

    The gridded map of Grand Rapids streets works out to about 17×17 intersections so for simplicities sake 300 intersections would add 65$ per day to the budget. If we bound it to the months where the average low does not drop below freezing we have around 200 days @ 65$ or an annual budget adder of roughly $13,000 significantly less than any lawsuit I would surmise.

    For any accumulation greater than 1″ heater requirements and costs would have to be adjusted accordingly. Improved sensing of moisture/temperature could counterbalance the additional heater requirements.

    When I first started this thought experiment I had anticipated much lower power requirements to remove snow/ice accumulation. I also anticipated much lower operating costs but when you think about the number of traffic lights in a given area and actually start summing them all up even a little additional power per light can quickly drive up utility budgets.

    On a separate note one of the earlier commenters mentioned LED failure due to the repeated switching of the signal indicators. A huge benefit of LEDs is that they don’t age like a traditional bulb due to high initial surge currents and can be switched on and off very rapidly. Dimming of an LED bulb is accomplished by switching it on and off faster than the eye can see and reducing the on and off time to achieve the correct intensity called pulse width modulation. The slow switching time between signals would not cause premature failures to LEDs.

    I had actually often wondered what the power savings might be if traffic lights employed a controller that reduced the intensity at night. During the day the LEDs should be as bright as possible, but at night they could easily reduce intensity by half and still be clearly visible (provided they aren’t iced over). After working through some of these calculations it might be worth pursuing as additional energy savings if not already done.

    JM

  128. So, why are people so fixated on heating solutions?

    The Snow Scoop Tunnel Visor seems like a clever and cheap solution. (From Joel (13:57:12))

    ————

    James Mayo (21:44:14) :

    >Dimming of an LED bulb is accomplished by switching it on and off faster than the eye can see…

    I really despise the PCM brakelights on cars these days. How fast do they have to
    flash so they are distracting when I turn my head quickly?

    I’d be happy if they just had a bigger resistor (another way you can dim a LED – reduce the current through it) or use a simple power supply to resude the current
    out.

  129. Salt solution.

    Glue a cereal bowl to the top of the light with rock salt in the bottom.
    The pigeons will bathe in this salt bath and “pollinate” the entire housing with salt spray. The salt will melt the snow, and eventually poison the avians.
    That’s called killing two birds with one stone… err.. rock.

  130. Ric,

    The only reason I can think that heating solutions are the dominant recommended solution is the description of the problem leads you down the path of looking at a way to achieve the higher thermal output of incandescents.

    I agree the scoop seems like the best way to solve this problem. Its passive, has a one time fixed cost and only needs to be fitted to units that suffer the problem which doesn’t burden the cost of the additional heating elements for those living in warmer climes.

    As far as LED dimming goes PWM can be done with the same number of components. Since brightness is a function of duty cycle varying levels of brightness are easy to achieve versus fixed resistors that gives you two discrete states. Most LCD screens have an LED backlight now that uses a power supply to control the current. It is definitely a lot better as the power supply can reduce or increase current within microseconds as opposed to milliseconds, making it impossible to tell it is switching at all, but the added cost isn’t really practical if you have lots of LEDs as it pretty much forces them to be wired in series to maintain the same current through all of them. If you had parallel groups of LEDs from the power supply they would not have the same current going through each and for a brake light that has several LEDs wiring all of them in series would require a very high voltage to drive that many at once.

    In the automotive market I’ve heard of meetings with suppliers that last all day arguing over 1 pennies worth of savings in a single component. Given how sensitive everything in a car is to costs if there is a microprocessor already controlling the LEDs then I’m sure most manufacturers would rather control brightness by PWM then any other method.

    In all the LED lighting applications I’ve worked with we try to have a minimum of 120Hz switching so as not to be noticeable. Your monitor is updating at a rate of 60-75 Hz and most people don’t have a problem, although a very small percentage of people seem to be sensitive to those sorts of things. The early DLP projectors had a color artifact known as ‘rainbows’ that only about 1% of people could see as a result of the color wheel inside the projector not spinning fast enough.

    JM

  131. Steve Goddard (10:19:55) :
    Many serious accidents happen at traffic lights, because people speed up to get through at the end of a cycle. Roundabouts are much safer because you have to slow down entering a roundabout, and because there is no reason to rush. You never have to wait for a light to cycle.

    Accidents aren’t caused by the traffic lights at an intersection, but by the drivers.

    Every traffic circle (roundabout/rotary) I’ve ever seen in the US had at least one set of tire tracks running straight across the sod from one entry to the exit on the opposite side, except for one on Ft. Dix, NJ — the tracks ended at the chipped paint on the M-48A5 tank sitting in the center.

  132. Give the traffic engineers a break. For over a decade, they’ve been told that snow and cold are about to become rare events, so how can we blame them if they finally started believing the spin and installed lights that won’t function in snow? Blame those that preached that we’re all going to hell in a warming hand basket.

  133. I don’t understand why anyone designs a PWM for LEDs that’s low enough to visibly flicker. I generally go for something above 1kHz (often significantly above, my last design was 50kHz) and this totally eliminates visible flicker. It’s not exactly hard to achieve these frequencies efficiently, you just need to use the right size MOSFET.

    120Hz is too low, I can easily see 120Hz flicker in my peripheral vision and I assume many others can too. (Peripheral vision seems to be more sensitive to flicker…).

    I’d double it at a bare minimum, but really, what’s wrong with 1kHz?

    As for why a heater? Well if the incandescents didn’t have this problem then the simplest thing to do is emulate them when necessary. Other solutions MAY be superior but you’d have to prove that they work at least as well as simple heat I’d say. I’d be worried that the wind-based solution could fail if wind is low or if there’s just a huge amount of snow.

  134. I may be missing something in this story but the first question that entered my mind was: How did this all weather product make it out of product development without undergoing adverse weather testing?

    It seems basic to me.

  135. photon without a Higgs (07:20:55) :

    Record cold and snow in the past two days, Thursday and Friday, in the US. Florida is getting it the worst. But Watts Up With that red dot in Florida??

    Location: West Palm Beach International Airport. What could be wrong there?

    I went back for a week:
    http://mapcenter.hamweather.com/records/7day/us.html?c=maxtemp,mintemp,lowmax,highmin,snow

    2 record high temps in the south amonst record cold…both airports. I was in Charlotte, NC on Friday, and they tied and probably broke the record for most days in a row below 20. I’m at home again and watching snow fall for the 7th day in a row. It hasn’t gotten above freezing here in 10 days, for an area with average temperatures in the 40s for this time of year.

    signing off from the “weather is not climate” channel.

    Steve

  136. A classic case of

    “Sub-optimising the whole system by optimising a subsystem”

    Why don’t the traffic folk ensure that they have someone who thinks ‘systems’?

    Redesign the LED light elements to be installed at an angle so that snow/rain falls off, and redo the hoods to make sure that snow/ice can fall directly down and out of the beam. While you are at it, design an LED unit that has Red, Orange, Green arrays all together. You will then only need one lamphouse!

    Attempts to put heating elements in existing housings seems to be a retrograde bodge. How does anyone tell if the heating element fails and the LED ices up? Why not use an incandescent bulb? Wow, light and heat at the same time, and anyone can tell if it has failed! Duh ….

    And while you are at it, install more roundabouts. Replace those scary mutiple lane light-controlled X-roads, and the frightful T-bone smashes. Make the traffic flow better.

  137. For those who question the temperature at Palm Beach Airport, or other airports… The ASOS/AWOS temperature sensors are fan aspirated. Since, when they installed the new Dewpoint Sensors, they did not turn off the mirror cooler in the HO 1088 temperature sensor, if an aspirator fan failed, you would, especially during low wind conditions, get high erronious temperature readings from the temperature sensor.

    Been there, done that. We had it happen at an airport out west, a couple of months ago… The indicated high temperature was in the 50s and 60s, while highs at other sites surrounding it were in the 20s and low 30s. Also, some other sites (RAWS and Highway measuring sites) in the vicinity were in the 20s and 30s.

    All this was without a “fault indicator flag” being set on the ASOS site. Apparently, there is no sensor/air flow sensor in the HO 1088.

  138. “Butch (04:03:02) :
    I may be missing something in this story but the first question that entered my mind was: How did this all weather product make it out of product development without undergoing adverse weather testing?”

    Some design decisions are bizzare to say the least. The center LED brake light array on my car is not readily user replaceable. In fact, it requires the total replacement of a trim panel, including painting and finishing. In my case, it took two attempts by (2) body shops and two complete trim panels. The panels used are adhesive and must be replaced if removed.

  139. Steve M. From TN (05:53:02) :

    jimH (07:05:31) :

    Ok, ok,……but what about the red dot in Roswell? ;-)

  140. “jimH (07:05:31) :
    […]
    All this was without a “fault indicator flag” being set on the ASOS site. Apparently, there is no sensor/air flow sensor in the HO 1088.”

    I always had the impression that it’s pretty safety critical for an airport to monitor temperatures. Is that not so?

  141. supercritical (06:20:20) :

    A classic case of

    “Sub-optimising the whole system by optimising a subsystem”

    Why don’t the traffic folk ensure that they have someone who thinks ’systems’?

    Redesign the LED light elements to be installed at an angle so that snow/rain falls off, and redo the hoods to make sure that snow/ice can fall directly down and out of the beam. While you are at it, design an LED unit that has Red, Orange, Green arrays all together. You will then only need one lamphouse!

    Then you get the added advantage that folks who are red green color blind will lose their location clue (ie which color light is which based on position rather than color ) and will have no idea what the light is trying to tell them under some conditions. And you have the added advantage of introducing a single point failure, if that one light goes out you lose all three lights, where on a conventional 3 element light if one dies, most of the time the other 2 are still working.

    That is also a systems decision ( and a human engineering consideration ). What is most efficient for the electronics and engineering may not be an ideal human interface design because of human factors.

    Larry

  142. Someone should have consulted an engineer before plunging headlong into the new green jobs of “scraping snow and ice off the led traffic lights”.

    Redesign the fixtures at huge costs, else you need heaters for the new “green” energy saving lights. Isn’t this how it works out, green is more costly than what is done now.

    Come to think of it, I wonder if any engineers were consulted about ethanol, windmills and solar panels. They could calculate for you whether you were actually gaining in the energy equation, or were you simply adding ‘green make work jobs’.

  143. “tarpon (10:18:48) :
    […]
    Come to think of it, I wonder if any engineers were consulted about ethanol, windmills and solar panels. They could calculate for you whether you were actually gaining in the energy equation, or were you simply adding ‘green make work jobs’.”

    They all produce more energy than was needed to set them up. It’s just pretty expensive because often it’s not that much MORE energy than was used to create them. As i said in a different thread: At the beginning of the oil age, they got 100 calories back for every calorie invested. ATM they’re down to 1:10 because the low hanging fruit has been eaten and new developments are more energy-intensive.

    I don’t have actual numbers for the ratios in wind and solar, but an estimate for bio fuel was about 1:3. In mankinds history, societies have collapsed when their energy harvesting efficiency fell below 1:3 so biofuel is surely barely viable energetically, and unviable economically.

  144. This isn’t the only oversight with LED’s the same goes with street lights. Communities all over the country have converted to LED street lights. The problem is that the street lights were spaced the coverage offered by incandescents. When the convert to LEDs which offer less coverage the street and side walks have darks spots. Criminals all over the country, drug dealers, prostitutes, muggers are figuring out that they can use the dark sports to their advantage.

  145. Jeff Id (07:45:22) :

    “All they need to do is put a sensor which detects when temps drop below 32 and activate a resistive non-light emitting heat source. Problem solved.”

    Why not be logical and activate a light-emitting heat source, like an incandesescent bulb, to help visibility and signalling?

  146. DirkH (09:33:43) :
    “jimH (07:05:31) :
    […]
    All this was without a “fault indicator flag” being set on the ASOS site. Apparently, there is no sensor/air flow sensor in the HO 1088.”
    I always had the impression that it’s pretty safety critical for an airport to monitor temperatures. Is that not so?

    Absolutely true. Aircraft takeoff and landing performance planning are based on pressure altitude (a function of temperature), and calm winds coupled with the local temperature converging with the dew point means you can expect fog in the summer and frost in the winter.

    And you haven’t lived until you’ve encountered ice-fog during your approach to the airport…

  147. I wonder how much gas energy is wasted by unnecessary stopping in zero cross traffic conditions. More lights should be blinking caution and not mandetory stops at all times, besides, a blinking caution yellow will use 50% less energy than a stop or go light.

  148. Snow has to fall horizontally enough to cover the traffic light (usually protected from vertical snow). This is not an usual snow fall, but rather a snow storm.
    In such condition, all vital traffic signs like STOP are covered too.
    And train warning lights can be covered too, because they are turned on only when there is a train, and off most of the time->snow won’t melt.

    I just wonder who, after a snow storm covered all vertical signs, is stupid enough to go through a crossroad fast enough to kill another driver.

    LED traffic lights is a good idea. It just need an additional system to prevent this specific problem. We talk here about billions watts being spent for nothing. We don’t talk here about uber green senseless technology, but efficiency improvement. Light bulb is maybe the only electrical device which remained mostly as primitive as 100 years ago.

    You want light? Use a LED.
    You want a heating system to remove snow 1 day per year? Add a heating resistor and a sensor, or simply a soft, light transparent film hanging in front of the light so snow won’t stick.

    And don’t forget that incandescence light bulbs heat is certainly a problem in summer, and traffic lights have to be designed to take this into account. There is certainly a cost related to heat protection too.

  149. Being color blind has required me to observe traffic movement well in advance of the intersection. If the other ignorant drivers would do likewise instead of fixating on their hood ornament, this would not be a problem.

  150. Progress. Most solutions have tradeoffs. We also had a lot of ice thrown from windmill blades during the storms. The tip of a wind generator blade can hit 180 miles per hour and toss ice build op a long distance.
    But the brochures claim they are perfect and safe.

  151. Well anybody who thinks LED traffic lights save energy, just hasn’t sat behind enough RED lights, with absolutely no traffic moving through the intersection in any direction. Any two year old child can make a better traffic decisions than most of these traffic lights. Remember they are programmed by the same sort of people who give us Micro$oft Windows.

    The problem with LED traffic lights is that RED came first, since GREEN was hard to make, and yellow even harder. So most traffic lights are set up to be mostly red in most directions most of the time.

    Of course it wouldn’t hurt to give drivers a driving test before giving them a driving license.

    Every place I have ever lived in the USA, any time traffic lights were out for any reason, drivers were supposed to treat them as a four way stop sign. Usually when that happens, the traffic moves better than when the lights are working.
    City politicians don’t know any way to improve traffic, other than putting in more lights. And they breed; you put in lights at one intersection, and it creates a traffic problem at another intersection, so you go and put some more in there.

    The trouble is, these days US public schools don’t teach simple problem solving any more. They are into these group projects, where nobody is required to think for themselves, and solve a problem on their own. If they put up traffic lights to tell people when to jump off a cliff, a whole lot of people would follow the lights instructions.

    Talk about a non problem; snow covering a traffic light. Those hoods are put there to stop drivers from seeing the cross street lights so they can’t tell which direction has the green light. If you drive into any intersection without knowing who has a green light, then you are a candidate for a Darwin award.

  152. The LED system does save power, but that is not their primary advantage.

    They also fail less often, but more often than manufacturers claim. (OK they have a warranty).

    **The Main Safety Advantage to LED traffic lights is that an entire intersection can be battery powered in an electric outage. These batteries last 4-6 hours, and are automatic. If the outage lasts longer, the DPW just sends a man by with a charged battery. This simple fact has very likely saved lives.

    After hurricanes have passed through here, we had cops at major intersections directing traffic for hours. They used cartons of road flares at night. What a scene it was! This cost of overtime alone probably excedes the price of the LED retrofit.

    One last thing….why not de-ice like they do with airplanes? Just think how the kids would like to see a truck come by squirting a hose line at the lights!

  153. This is a very small issue compared to the benefits of the units. I always thought that traffic lights were a perfect match to LEDs, a single wavelength light source.

    On the rare occasion you have horizontal snow to the extent required to cover the lights, it’s not just the lights that get covered but every safety sign, etc. Not to mention general visibility is going to be terrible while it happens.

    In all the years I’ve seen the LEDs I’ve NEVER seen this problem, and we get plenty of snow and snow storms here.

    No government, or company for that matter, builds out infrastructure for the express purpose of taking care of the 0.01% event, “make due” is usually the only cost effective way. If it is actually common in an area, I’m sure a solution will be forthcoming to resolve this apparent deficiency. I would say, available winter maintenance money is better spent in prompt good snow removal.

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