There are a ton of these in my town. I'm not 100% sure what light they use, but I believe they use Metal-Halide. ( They give off a white-bluish glow. ) To my knowledge, they started putting these up around eleven years ago. These are large fixtures.

They might be Lumec DMS50 series.

What state is this in? I have seen these in FL on the section of the highway, except they are on fancier poles, and I think are HPS, but I haven't seen them at night myself. They were installed around the same time, about 2004-2006 timeframe.