Trucking on I-35

I'm going to work this morning and I come upon an 18 wheeler driving erratically. He was in the middle lane weaving over to the left until he hit the traffic buttons, then he'd go right until he hit the buttons on that side. I followed him for about 3 or 4 miles, then I called 911. I turned him in to the police. Normally, I wouldn't do that, but this guy was making the traffic worse. Everyone was slowing down when they caught up with him, then they wouldn't pass because they were afraid he was going to hit them. I pulled up even with him and he was either yelling or singing real loud. I think he may have been awake with some assistance, if you get what I mean.

Don't know what happened, because I exited to go to my office. Ahh...all in a day's work.