When cities started replacing the old, incandescent bulbs of traffic lights with new LED arrays, it came with all kinds of wonderful upsides. LED arrays last much, much longer than bulbs, which need to be replaced as often as every two years. They also require much, much less energy, which can save thousands of dollars in electricity costs. They're also much more efficient, generating almost nothing in the way of waste heat the way incandescent bulbs do. And it's that last one that proved to be a problem.
The myriad advantages of LED lights, and specially-made arrays designed to fit right inside the fixtures where incandescent used to go, lead to to the widespread adoption of these better alternatives. But alongside it, , came an unexpected problem. Thanks to all the excess heat generated by incandescent bulbs, traditional traffic lights were able to weather even the worst of snow and ice storms, melting off any accumulation that would threaten to obscure the view. LEDs, owing to their greater efficiency, were not.
This flaw, unusual and unexpected as it was, became an immediate point of argument against the lights in general, ignoring both their countless benefits and the fact that this issue, while surprising, was also exceedingly rare. Watson explains in great detail how the problem proved to be a significant stumbling block for a technology that was clearly superior to its alternative in virtually every other way:
Ultimately, solutions like LED arrays with built-in heating modules emerged for the rare cases in which this new weakness was in fact a considerable concern. But more than anything, time won out to show that the downsides, however startling, were not quite so bad in context. Sometimes folks just need a little bit to absorb what any engineer could have told them from the jump.