Placards must be placed on the outside of vehicles carrying hazardous materials. They identify the specific class or classes of materials being carried and warn others of relevant hazards.

If making a left turn where there is more than one available turn lane, you should always choose to take the rightmost lane. Large vehicles often have to swing right to make left turns, so it is safer for you to have other left-turning traffic to your left. This will allow you to have the best possible view of other turning vehicles and will lower the risk of your vehicle colliding with them.

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.

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.

Retarders are mechanisms in some vehicles that help slow a vehicle and reduce the need for braking. However, using a retarder may cause wheels to skid when they have poor traction. Turn off retarders when traveling under wet, snowy, or icy conditions.

After you start the engine, keep an eye on the gauges. Oil pressure should rise to a normal level within a few seconds of the engine being started.

Always slow down before entering a foggy area. Use low beam headlights, avoid passing others, and avoid stopping on the side of the roadway. It is safest to completely avoid driving under foggy conditions, if possible.

If you are being tailgated, it is advisable to open up the space in front of your vehicle, making it easier for the tailgater to get around you. Speeding up may be counterproductive because the driver may continue to tailgate you at the higher speed, only increasing the danger.

When performing a static leakage test on a triple combination vehicle with air brakes, the leakage rate should be no more than 5 psi in one minute. If air leaks from the air brake system at a quicker rate, the vehicle should not be driven because something likely needs to be repaired.

If a vehicle carries red reflective triangles, the driver should place three of them as warning devices when the vehicle is parked on the road.

According to the National Sleep Foundation’s Sleep in America poll, 60 percent of Americans have driven while feeling sleepy, and 36 percent admit to having actually fallen asleep while driving.

All commercial motor vehicles are required to be equipped with the proper emergency equipment. This may include spare electrical fuses; three red reflective triangles, six fuses, or three liquid burning flares; and at least one properly charged and rated fire extinguisher.

When using a fire extinguisher, you should stay as far away from the flames as possible and aim at the base of the fire.

In places where water collects on the road, it is possible for a vehicle to hydroplane. Low tire pressure or worn tire tread makes this more likely to happen. If there is enough water on a road surface, hydroplaning can occur at speeds as low as 30 mph.

When inspecting a vehicle equipped with power steering, check the hoses, pumps, and fluid level. Be sure to check for and repair leaks before operating the vehicle.

If a pre-trip inspection reveals a load to be oversize, the driver must confirm that all required signs, flags, lamps, and reflectors are safely and properly mounted, and that and all required permits are in their possession.

Driving while fatigued can be extremely dangerous. Strategies for preventing drowsiness while driving include getting a full night's sleep before a trip; having someone ride with you so you can take turns driving; scheduling trips for times during which you are normally awake; and avoiding medications that may cause drowsiness.

Correctly following the steps to couple and uncouple trailers is vital to safely operating a combination vehicle. After connecting the air lines to the trailer while coupling, you should supply air to the trailer.

Railroad-highway crossings may be difficult to cross if you are pulling a trailer with low underneath clearance. In particular, both low-slung units and single-axle tractors pulling long trailers are especially challenging to drive over raised crossings.

If a tire fails, braking could cause a loss of control. Unless braking is necessary to avoid a hazard, you should stay off the brakes until your vehicle has slowed considerably. Only then should you brake very gently, pull off the road, and stop.