What are the LED Blue Lights found at random traffic lights, light rails, and city public areas?

Question

Lately I have noticed blue lights on top of poles or light poles at traffic lights, along the interstate randomly placed, and along light rail (public transportation) poles. Not the blue lights that signify a call box, but just randomly placed.

Answer 1

Those blue LED's are signal markers.  Basically, whenever an emegency vehicle needs to run a red light or cross over some railroad tracks, they intiate a signal beacon on their vehicle (example being the strobe light on the front center of a fire engine).  This beacon hits a receiver on the traffic light, and starts a process to change the light from red to green.  The blue LED is a way for the emergency personell to tell whether or not the traffic light is going to change, or has already changed.  If the blue light is on, the light is red, if it is out then the light is green. If it is blinking then it is going to change from red to green really quick!  The funny thing about this is that most city buses have the same transmitter as the cops or emergency vehicles, that way they can make sure to stay on their time schedule.

Answer 2

keeps planes above that area sometimes markers for city

Answer 3

if your city has an airport they are probably just  now getting around to updating their freeway or highway. But you can always email or contact your local Dept. of Transportation to find out exactly why but I am pretty sure it is because of aircraft.