Street Light Bulbs Being Changed (Cool Picture)

Have you ever wondered how the city changes their street light bulbs on those outdoor pole lights that are many feet into the air?  I've never seen one being changed before.  While sitting at a stop light the other day, I snapped this picture of a city worker in a cherry picker hosted to its maximum height changing out street light bulbs.  That takes a certain amount of guts to do that, I suppose.

I found myself wondering what kind of  light bulbs they were replacing it with. Is there a catalog of street light bulb options  out there? Or is there just one kind?  Does the city purchasing manager have multiple street light bulb suppliers they can choose from?    And why this light bulb?  Why did the city decide to change the light on this outdoor pole.  Then I found myself wondering how many city workers does it take to change street light bulbs?  The answer will always be too many.  Then the light turned green and I drove away.