In general, vehicles carrying hazardous materials are required to display diamond-shaped warning signs on all four sides. These warning signs are called "placards."

To obtain a hazardous materials endorsement, you must pass a security check conducted by the Transportation Security Administration (TSA).

If you are driving a vehicle that is transporting Class 1 explosives and it is involved in an accident, you should warn others of the danger, keep bystanders away, and not allow smoking or open fires near the vehicle. Before separating the vehicles involved in the collision, remove all explosives and place them at least 200 feet away from the vehicles and any occupied buildings.

Diamond-shaped signs called placards are placed on bulk packages and on the outside of vehicles to warn drivers and others of the presence of hazardous materials. It is the responsibility of the shipper to place the placards, and it is the responsibility of the driver to verify that the correct placards have been placed.

If transporting Division 1.1, 1.2, or 1.3 explosives, you must follow a written route plan. Whenever placarded, avoid heavily populated areas, crowds, tunnels, narrow streets, and alleys. Be sure to research any restrictions that may apply to the routes you plan to take.

Hazardous materials warning placards are usually diamond-shaped.

Radiation will surround each package of radioactive materials and pass through to all nearby packages. The number of packages that can be loaded together is controlled.

The shipper of hazardous materials is responsible for identifying the product's identification number; proper shipping name; hazard class; packing group; and correct packaging, labels, marking, and placards.

Except when parking briefly to perform necessary functions for vehicle operation (such as refueling), never park a vehicle carrying Division 1.1, 1.2, or 1.3 explosives within 300 feet of a bridge, tunnel, or building. Never park such a vehicle within five feet of the traveled portion of a road. Such vehicles should be parked only briefly.

When carrying Division 1.1, 1.2, or 1.3 explosives, you should not park within 300 feet of a bridge, tunnel, or building, unless you are parking for a short period of time while performing an operational necessity, like refueling.

When a shipper packages hazardous materials, they certify that the package has been prepared according to Hazardous Materials Regulations (HMR). Unless a package is clearly unsafe or noncomplying with HMR, you may accept the shipper’s certification concerning the proper packaging of a material.

If a package of hazardous materials is not large enough to display the proper label, the label may be placed on a tag that is securely attached to the package.

Column 2 of the Hazardous Materials Table lists the proper shipping names and descriptions of regulated materials.

If you discover a leak in a cargo of hazardous materials, identify the materials in question by using the shipping papers, labels, or package location. Do not touch the leaking material.

The loading of a tank with hazardous materials must always be watched by a qualified person. This person must be alert; have a clear view of the tank; stay within 25 feet of the tank; know the hazards associated with the materials; know what to do in an emergency; and be able and authorized to move the tank if necessary.

Hazardous materials should always be loaded away from heat sources. Many materials become more hazardous if their temperatures increase.

A person should not smoke within 25 feet of a placarded tank that is used to transport Class 3 (flammable liquids) or Division 2.1 (gases) materials. Additionally, no person should smoke or carry a lit cigar, cigarette, or pipe within 25 feet of any vehicle containing Class 1 (explosives), Class 4 (flammable solids), or Class 4.2 (spontaneously combustible).

When experiencing a cargo fire, it may be a bad idea to open the doors to the trailer. Doing so allows oxygen to enter the area, potentially causing the fire to flare up and expand.

One clue that a shipment may contain hazardous materials is that the shipper is in a line of business that you would expect to involve hazardous materials. Examples of such businesses include paint dealers, chemical suppliers, scientific supply houses, pest control companies, agricultural suppliers, and dealers in explosives, fireworks, or munitions.

To drive a vehicle of any size that is used to transport hazardous materials, you must have a CDL with a hazardous materials endorsement.

In the event of a leak in a cargo of hazardous materials, do not continue to drive any longer than is necessary for safety. Continuing to drive would result in a larger area becoming contaminated. Instead, park the vehicle, secure the area, stay with the vehicle, and send someone to get help.

When transporting hazardous materials, you may leave your vehicle unattended in a safe haven. A safe haven is a location that has been approved for parking unattended vehicles that are loaded with explosives.

If you need to refuel a vehicle carrying hazardous materials, you must first turn off the engine. While refueling, someone must be at the nozzle and controlling the fuel flow at all times.

A vehicle with tanks that are used to transport hazardous materials must always be stopped before being driven over railroad tracks, even if the tanks are empty.

Fighting a hazardous materials fire requires specialized training and equipment. Unless you possess these yourself, it is best to let emergency personnel deal with the fire.

You must examine each tire on a motor vehicle at the beginning of each trip. The only effective way to check tire pressure is by using a tire pressure gauge.

A driver transporting chlorine in cargo tanks must have an approved gas mask in the vehicle, as well as an emergency kit for controlling leaks in dome cover plate fittings on the cargo tank.

Keep liquid discharge valves on a compressed gas tank closed except when loading and unloading.

When transporting hazardous materials, shipping papers should be kept in a pouch in the driver's side door, or in another location where the driver is able to easily reach them while their seat belt is fastened. The papers must be easily visible to anyone who is entering the cab.

The use of cargo heaters is not always permitted. When transporting materials that are categorized as Class 1 (Explosives), Class 2.1 (Flammable Gas), or Class 3 (Flammable Liquids) materials, heaters are generally prohibited.