In many cities, traffic lights are being retrofitted with low-maintenance LED illumination. One of the best advantages that an LED offers is a very long lifetime. We've all had to change light bulbs, and sometimes, troubleshooting these bulb failures can be quite troublesome, such as in Christmas lights. LEDs typically have rated lifespans in the thousands of hours, sometimes as high as 100,000 hours. That's equivalent to continuous operation for more than 10 years!
How can LED night lights cost only pennies per year to operate, and LED replacement bulbs claim to save hundreds of dollars over the bulb's lifetime? Currently, the most efficient LED bulbs produce over 90 lumens per watt (lm/W). Incandescent bulbs are rather inefficient, producing about 15 lm/W and dissipating the rest as heat. Even "energy effiicent" CFL (Compact Fluorescent Lamps), which are fragile and contain mercury, produce about 60 lm/W.
Many flashlights and gun-mounted weaponlights are switching to LED for drop resistance and more reliable operation. This is because LEDs, or Light Emitting Diodes, are semiconductors, classifying them as "solid state lighting." This means that the light source is much more resistant to extreme temperatures, shock, and vibration, factors that can lead to early incandescent failure.
LED taillamps are often marketed as part of a vehicle's safety features because they light up instantly. Both incandescent and CFLs are slow starting, especially with CFLs, which take several minutes to reach full brightness. Some cars use LEDs for the high mount stop lamp (sometimes called the third brake light) and incandescents for the regular stop lamps, making the difference easily noticeable. This fraction of a second could be the difference in whether or not the car behind you stops in time.