LEDs do, however, offer several advantages over traditional incandescent bulbs. For example, ABC News reports that the state of Wisconsin switched to LEDs in 2002 to save energy and money: LEDs last longer and cost 80 percent less to operate than traditional bulbs. State officials say some LED traffic lights installed in 2002 are still in place, whereas incandescent bulbs have to be changed approximately every 18 months.
In some cases, LEDs save more than money. When incandescent bulbs burn out, they go out completely, without warning. On the other hand, LEDs often go out in parts, leaving part of the string of LEDs inside the traffic light operative and emitting light. Drivers then alert the authorities, who send out a crew to replace the failing light.