Mystery Of The Blinking Light

What do you think this could be?

I was sitting at a stoplight on Route 240 in Fairhaven today, when I noticed something. At first, I thought it might be a hidden camera to catch people who blow through red lights. I thought it could take a picture of the offending car...and the RMV could send a ticket. I've heard about that happening in other states...but never here in Massachusetts. After getting a better look, it looks like a mall blinking white light. Have you ever noticed one of these things on top of a stoplight?

I mentioned it to someone at the station and they said that they thought it had something to do with emergency vehicles. Maybe it is a sensor for the flashing lights of a police cruiser or fire truck...and it changes the light to green to make way for them?

Anyone know for sure what it is?

It also got me thinking...if I flash my high beams at it...would the light change green for me?