Cities and states can enjoy numerous benefits by switching from high pressure sodium to LED lights in street lighting fixtures and traffic signal lights. These benefits included better visibility for drivers, lower power consumption for street lights, and reduced maintenance when compared to the old lighting technology.
On the negative side, switching from yellow light to the whiter LEDs has the effect of keeping people awake at night, depending on their proximity to the light source. LED street lights that use white light to help keep drivers awake and aware provide safer driving, but could negatively affect the quality of sleep for people who do not block out the light at night.
Are we ready to add another negative to the list of switching from old technology to LEDs? In wintery conditions, when snow covers stop lights, LEDs do not burn hot enough to melt the snow. A recent report out of Japan cites local police, who have discovered problems with the lights. When covered with snow, drivers can not tell which color the light is, or when they switch. As snow accumulates, driving conditions become more dangerous.
Currently in Japan, the snow has to be removed manually from the stop lights during winter blizzards. Having city workers driving around throughout the winter removing snow reduces the benefits of switching to LED, resulting in increased power consumption (through more driving) and even greater maintenance costs. Even if these increased costs are not enough to offset the long-term savings by switching to LED, they can lengthen the payback period for investing in more expensive LED over traditional light bulbs.
A simple solution would be to install some sort of heating mechanism in the street light fixtures that could melt the snow if it accumulates past a certain point. Of course, this has the same problem as having city workers remove the snow manually. A heater would use more energy, negating some of the energy saving effects of switching to LED. It would also be one more piece of equipment that would need servicing and maintenance.
However, LEDsMagazine wrote an article on this very issue, detailing how Colorado has utilized a "snow scoop" tunnel visor to force wind to dislodge the snow. This simple item can be installed on most existing traffic signals at a relatively low cost. If the wind is powerful enough to blow snow into the stop lights, then it is likely powerful enough to blow the snow off of lights, saving city workers a trip out to remove the snow manually.
As costs come down, switching to LED for a large number of applications makes sense. But cities will have to take into account more factors than simple energy savings calculations when it comes to automotive applications such as stop lights. Traditional incandescent lamps may burn out after only a couple thousand hours, requiring yearly replacement, but that might be preferable to dusting off LED street lights every time there is a bad snowstorm. Thankfully, these problems are already being addressed by the industry.
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