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January 14, 2010...December snows blew up some interesting news as a year-end reminder that even when you're doing things right, critics make their living off criticizing, not praising. In this case, the 'big news' was that LED traffic signals, the SSL industry's poster child of adoption curve success, don't melt snow. The reporting told us that because LEDs use so much less power (true) that they generate less heat than the old incandescent bulbs (true) and don't melt the snow off the traffic signal lenses (true) like the incandescent bulbs did (hmmm... do they? always?). The news made headlines that labeled them as "unintended consequences" as though this good idea was suddenly a bad idea because the new thing didn't do something that the old is presumed to have done. I call that 'missing the big picture'.

First and foremost, let's make it clear that the fact that LED traffic lights don't melt snow does not come as a surprise to anyone in the LED traffic signal business. They kind of knew this, and as I polled around some folks that are or were involved in the LED traffic signal market, this also wasn't a surprise to the customers (typically municipalities) either. One source reported that over a number of years, they had only gotten one request from a customer in Canada to propose a way to melt snow on the signals. In that case, the customer decided it wasn't worth the additional cost to deal with it. What, not worth the cost? They must have been looking at the big picture.

To simplify the discussion, although I truly tend to doubt that incandescent signals always melted the snow off (is that yellow light really on long enough to generate enough heat to melt accumulating snow), let's unconditionally grant that incandescents did and LEDs don't. I know first hand that it's not true, having lived in the Lake Tahoe California area for a winter a few decades ago. Good snowstorm, steady wind, and some traffic signals were obscured. Seems to me that's why they invented the brake pedal. But, let's go ahead and grant the old stuff a pass and claim they were always snow-free. From that position, we can launch into the other half of the story that wasn't reported... the LEDs are probably saving many more lives by simply being on in the first place, than they would ever cost due to rare snow obscuration events. Heck, one could claim that electricity is the culprit, if anyone has ever been injured in a traffic accident when the power failed and the signals went dark. It might sound something like, "Before these ee-lectric traffic signal thingies, we'd only have that old, reliable stop sign, and never have we seen one of them fail... well, except when people didn't see it and would run right on through it."

So here's the truth... the LED traffic signals seem to have an incredible ability not to fail (7+ years and counting for many). Incandescents failed regularly, but unfortunately not like clockwork. Given their on-off cycle, reports seem consistent that they would typically have a 8000 hour life span, or a year or two, depending on the cycling. That suggests that any individual signal could be expected to go dark for some portion of at least a, if not longer, once a year. If we make an optimistic guess that they would be dead at least 4 hours before the city repair crew got around to them when they failed during the day, and say something like 10 hours average when they failed at night, we have something we can get our heads around. Average of 4 and 10 is 7 hours per year, that any given signal is going to be dead... not signaling... presenting the opportunity for someone to run them and crash into someone else. If red and green are equally important, that's potentially 14 hours of "danger" per signal head each year. 14 hours with some certainty, versus a few hours if a once in a great while snow storm with just the right kind of snow and wind-angle combination hits on a particular year (presumably in the kind of storm that thins traffic to virtually zero, and if you're driving, common sense suggests no one can stop predictably). Bear in mind that much of the US, from the west coast, across the mid-south, and on to Florida rarely sees snow, and if it does, it won't ever reach the magnitude needed to block the light from a traffic signal. But those same states would see just as many incandescents fail for just as many hours each year. Heeellllooo? 7 years, some rare darkness on some heads due to a rare snow event every few years, versus a predictable period of dark from every signal everywhere, every year. Which one is dangerous? Can you hear us media? We lost one life in 2009, but how many did we save since those LED traffic signals were installed?

So, can we do better? Maybe, but at what cost to get to "never fails to signal"? $100K in this city, $200K in that one... Is that money best spent on preventing the possibility of snow accumulation in the next blizzard because one person in the US, as unfortunate as that is, had their death attributed to an obscured traffic signal in 2009? Could those hundreds of thousands perhaps be better invested in an extra ambulance in an underserved area, or perhaps in adding another police officer, or even more to the point, in adding a traffic signal to a current high-risk, uncontrolled intersection? Big picture.

As an industry, let's make sure we don't get caught up by what the critics may turn into the 'potential for the disaster' story of the day. It doesn't matter if it's "if you stare at an LED, it could blind you, and now we've installed them in our TVs!" or "they're talking about LED automobile headlights, and we all know that LEDs can't melt snow off of traffic signals, so what's going to happen in our cars!" Yep, we've kept that one in sight for years, and that one does need to be solved before LEDs can work there. We're keeping the big picture in mind, and we just need to share it every chance we get.

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