In the United States, there are 3 classes of CDL (commercial driver's license) which require physical exams:
Class A truck
Any combination of vehicles with a GVWR (Gross Vehicle Weight Rating) of 26,001 or more pounds (11,793 kg) provided the GVWR of the vehicle(s) being towed is in excess of 10,000 pounds (4536 kg).
Class B truck
Any single vehicle with a GVWR (Gross Vehicle Weight Rating) of 26,001 or more pounds (11,793 kg), or any such vehicle towing a vehicle not in excess of 10,000 pounds (4536 kg) GVWR.
Class C truck
Any single vehicle, or combination of vehicles, that does not meet the definition of Class A or Class B, but is either designed to transport 16 or more passengers, including the driver, or is placarded for hazardous materials.
He was licensed "Class A" w/NT endorsement which means licensed to pull double, triple trailers, tank trucks. His specialty was lowboy hauling. I believe the largest lowboy trailer he pulled was 15 axle.
Within the trucking industry, the heavy haulers are considered the creme de la creme, a specialty, if you will. There is no school to teach heavy haul. DH said you either have a knack for it or you don't. You have to know all about tandem weights, all kinds of things to be legal on the road, & of course, you have to have some talent/skill. No damage to the rig or the load! He was no stranger to the state troopers. Just comes along w/the territory of rules & regulations. This bunch tend to be family men. He avoided truck stops whenever possible due to the crowd they tend to draw.
He raced the company cab in the Semi drag races one year. That was a hoot.
Considered himself a "rough, tough, cocoa puff", hard on the outside, soft on the inside. He died Dec '07. I have heard lots of stories, lots of ranting about &^%$*# people on the road who he swore had a %^#$*^ death wish.
I remember he was up in the timber one time w/a boom truck loaded, a cliff on the other side of him. There was some sales rep from some company trying to tell him how to secure the boom. DH looked up, simply said: "get away from me."
Another time, he was in the downtown industrial area, parked, separated the cab from the trailer to unload. By the time he got back to the cab, somebody had parked between the cab & trailer so he couldn't hook back up & leave. OMG, I was on the phone w/him @ the time, he was absolutely furious @ the sheer stupidity of people.
Our pickup had an extra fuel tank in the bed where most people have the toolbox when we vacationed together. He had a switch rigged up on the inside where he would flip it to switch tanks w/o having to stop as frequently to fuel up. Always knew I was in good hands w/him.
Hope you enjoyed my couple of stories.