I just spoke with Raymond Deese. He is founder of Electro-techs in Corona, California. Mr. Deese could be called "Mr. LED." He's been working with LEDs since 1981. His firm built and sold the first LED traffic lights in the world twenty years ago. They're now the only American maker left, competing in a global marketplace. Deese has seen LEDs become the prevalent form of traffic light.
He pointed out that many states, like California, essentially require all new intersection lights be LED. Why? Energy savings of up to 90% over the old-fashioned incandescent. The replacement cycle is much longer for LEDs. Deese estimates that two-thirds of America's traffic lights are now LED as are most railroad signals. Deese's LED signals are in wide use in Alaska, Canada and New England--all places that can get a little snow. In those very cold winters up north incadescents often melted snow or ice that then picked up road dirt and cinders and then refroze completely blocking out the light inside. So the old system was never trouble free either.
Deese said, ironically, that cold is never an operational problem for his LED signals. They love cold. And he's never heard of anyone having serious problems with the LED signals due to the weather. No orders for signal wipers. But, he said, in Alaska they have to heat their signal control cabinets so they continue to function. LEDs do have occasional problems in extreme heat. But even then they function better than incadescents did.
LEDs, like windshields, are here to stay. Snow happens. Deal with it ONTARIO ON LED TRAFFIC LIGHTS
Here's a response from the Ontario distributor of Deese's LED traffic signals. They do get some serious snow up that way: "Yes, it's a well known issue. There have been occasions where the temperature and wind direction are just right for accumulation on the signal face but it's really unusual for all these factors to come into play at the same time to have this happen. I'm not aware of any accidents caused by it because it's so unusual and when it does happen people can still see light if they look and it's still better that an intersection that has lights that are not functioning at all in which case people typically come to a stop at the intersection as if it were an intersection with stop signs. "Raymond Lalonde (Dir. Sales), SOLAR SIGNALS INC."