I-45 between Dallas and Houston, is a test road for self driving semi trucks. I drove down last week and saw one. I drive that road often and usually see more. They are full size semi trucks. Not sure if they are loaded or not. They do have a person in the driver's seat for emergencies, but they are just sitting there, not touching the steering wheel.
I personally cannot wait for a self driving vehicle. On the interstate, not for around town. But it makes sense if there are limited entrances and exits for mile after mile. If I can just click a button like cruise control, why not?