That is the actual trailer the container sits on top of it.
I live in Miami, and see these trailers without their containers all the time.
What is weirding me out is a practical blackout locally about what is going on in the port, even the blood and guts station isn't wall to wall on what is happening there. They are running infommercials
I just briefly switched from Fox to see if any other news outlet was covering it. Even CNN not covering (they're doing some report on the "terrible" economy. Presser given by several agencies coming up any minute.