The emergency air line (also known as the supply line) has two functions. The first is to supply air to the trailer air tanks, and the second is to control the emergency brakes on combination vehicles.

Pre-trip inspections should be conducted in the same way every time. This will reinforce the steps, making it less likely that you will forget to inspect something important.

Always change lanes slowly and smoothly. If you did not see drivers who are already using the lane you wish to occupy, this will give them a chance to get out of your way or honk their horns to alert you. Always signal before changing lanes.

You should not brake while making a quick turn to avoid a hazard. Doing so could cause your wheels to lock and make your vehicle skid out of control.

Every combination vehicle has two air lines: the service line and the emergency line.

If your vehicle gets stuck on railroad tracks for any reason, you should immediately exit the vehicle and walk away from the tracks. Contact the proper emergency authorities.

Be cautious when driving near people who are working on a disabled vehicle on the side of the road. They may be focused on the repair and not paying attention to nearby traffic.

You should test the tractor protection valve by allowing the air supply to properly charge, turning off the engine, then releasing air from the system by pressing the brake pedal several times. The tractor protection valve should move into its emergency position when psi drops to an unsafe level.

Check your engine during the pre-trip inspection. After starting the engine, you should listen for unusual noises.

If a vehicle is carrying hazardous materials that require placarding, there must be identical placards placed on the front, rear, and both sides of the vehicle.

It is important to observe other drivers' behaviors and identify clues that indicate when person could be driving impaired. Drivers who have had too much to drink, are sleepy, are on drugs, or are ill can present hazards to other drivers. A person driving with their window open in cold weather may be impaired.

It is important for you to be aware of your surroundings at all times. To do this, regularly check your mirrors.

Drivers with blocked vision may pose hazards to others on the road. Examples of such drivers include those who haven't scraped ice off of their windshields; those driving vehicles loaded with large items blocking the windows; and those who are driving rental trucks without being used to the limited rear visibility of a truck.

When coupling glad hands, make sure to couple together matching glad hands. To help drivers avoid mistakes, color coding is sometimes used. Service lines are often coded with the color blue and emergency lines are often coded with the color red.

Escape ramps are constructed in areas with steep downgrades to allow a means of safely stopping runaway vehicles. They consist of a long bed of loose, soft material, and sometimes an uphill slope.

Be sure to test the trailer emergency brakes before beginning a trip. After ensuring that the trailer rolls freely, you can test the emergency brakes by pulling out the trailer air supply control, or placing it in the "emergency" position. Pull forward slightly with the tractor and make sure the trailer does not move.

To reduce the risk of a surge in a tank vehicle, slow or stop while keeping a steady pressure on the brakes and do not release the brakes too early. Brake well in advance of a stop and increase your following distance.

Fog can quickly deteriorate drivers' ability to see the road, other drivers, and other hazards. Avoid driving in fog if at all possible.

When turning or changing lanes, you should signal early and signal continuously. Cancel your turn signal once the turn or lane change is complete.

To reduce the risk of developing aggressive driving behavior, you should take measures to manage your stress. One strategy to do this is to simply take a deep breath and accept your circumstances if you realize you will be late to your destination.