The power unit only of a tractor trailer.

It is short for refridgerated trailer, or it could refer to the actual temperature unit on the front of the trailer.
Diesel Exhaust Fluid
Diesel exhaust fluid DEF, also referred to as AdBlue, is a crucial substance utilized to minimize the volume of harmful air pollutants released into the atmosphere by diesel engines. This resourceful liquid is specifically designed to reduce the level of toxic nitrogen oxide (NOx) emissions by converting it into harmless nitrogen gas and water vapor.

(Sailboat Fuel)
(Carrying Dispatcher Brains)
A deadhead truck has a trailer attached but carries no freight. Deadheading means driving a cargo carrying truck (semi-truck) pulling an empty trailer. Deadheading often happens when a trucker returns or backhauls the empty cargo container to the point of origin.
Trucking terminals actually have two meanings. One, is where company trucks all park, get service, drop or pick up trailers, get maintaince done, etc. At some locations they have regional planning or office personnel.
Another meaning is a big building and yard that has freight dock doors on all sides and trucks back in loaded or empty trailers and freight is dispersed among other trailers as needed to go in different directions or locations.

Technically, super singles are single tires that offer the capacity to replace the capacity of a dually set. Most commonly the term refers to wide-base tires (their proper name) used to replace dual-wheels on semi-trucks and trailers. This approach turns 18-wheelers into 10-wheelers. You used to see these tires alot, but now not so much. I think they actually failed more than the regular single tires.

A truck pulling double or triple trailers. 
or Flatbed

Scalehouse
Department of Transportation (DOT) weigh stations are essentially checkpoints to ensure there are no overweight vehicles (specifically commercial trucks) on the road. They also ensure that companies in the trucking industry comply with state and federal laws.
That's what we call an ambulance in route
State trooper/State Police Officer
weigh station/inspection point that trucks must go in if not given a bypass
Tire tread that has come off a truck and is laying in the road.

Motorcycle Cop

Sheriff Deputy
Semi truck with many lights on the tractor and trailer

Motorcycle Cop pointing his radar at traffic

law enforcement watching traffic from a helicopter

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