SW Waterfront

What the Helen of Troy are these?

15101177270_fcd13388bb_z

“Dear PoPville,

On 4th St, SW near Virginia Avenue. There are two big white boxes with a wire connecting them (hard to see in these pics) underneath the train tracks. They appeared about a month ago and I can’t figure out what they are.”

15101344017_6d28621ce2_z