While there are risks associated with transporting dangerous goods, these materials still need to be moved around the country and further afield. As a result, these substances have to be transported with care and attention as they do pose a risk. As a result, to ensure that they are transported correctly, they have all been classified, enabling transport companies to move these different classes of materials around safely while keeping in line with the law.

As a result, different hazard signs are used to differentiate between the different dangerous goods and that makes it important to understand the placards or individual warning signs for each item.

The Transportation of Dangerous Goods by Road

Agreement concerning the international carriage of dangerous goods by road – ADR is an agreement of 51 countries including the UK to all operates under the ADR regulations.

The dangerous goods might be flammable or classed as an explosive which means that they have to be transported with care. Safety is paramount but the law does stipulate that these goods have to be transported correctly. This will mean that the driver is qualified and that the right vehicle is used to maintain safety throughout. These different classes pose different risks while on the road, so they all have to be treated with care.

ADR Hazard Signs & Classifications


CLASS 1 – Explosives

There are a number of materials that pose a risk which is why this class is broken down into subclasses. This means that it can cover the likes of explosives with a mass explosion hazard, explosives with a severe projection hazard and explosives with a minor fire or projection hazard.

CLASS 2 – Gases

There are three different classes of gases and these are known as flammable gas, non-flammable, compressed gas and toxic gas. The kind of goods you can expect to fall under this category includes the likes of helium, neon and nitrogen.

Flammable Gas

CLASS 2.1 – Flammable Gas

Acetylene gas is a highly volatile flammable gas commonly used for welding.

Non-Flammable Gas

CLASS 2.2 – Non-Flammable Non-Toxic Compressed Gas

Toxic Gas

CLASS 2.3 – Toxic Gas

Toxic gases are harmful to living things, Carbon monoxide (CO) is produced by vehicles.

Flammable Liquids

CLASS 3 – Flammable Liquids

This class will cover all flammable liquids which include white on red or black on red. This can include products such as petrol and kerosene.

Flammable Solids

CLASS 4.1 – Flammable Solids

This is another varied class with a number of potential materials that have to be transported with a warning. This can include flammable solids, self-reactive substances and solid desensitised explosives. This can include wetted trinitrotoluene (TNT).

Spontaneously Combustible

CLASS 4.2 – Spontaneously Combustible

This involves transporting those substances that are liable to spontaneous combustion which means that they interact with oxygen.

Dangerous When Wet

CLASS 4.3 – Dangerous When Wet

These substances will emit flammable gases once they come into contact with water. This can include calcium, sodium and potassium.

Oxidising Agents

CLASS 5.1 – Oxidising Agents

Some substances can self ignite when in contact with a fuel source. This includes the likes of nitric acid and sulfuric acid.

Organic Peroxides

CLASS 5.2 – Organic Peroxides

Organic peroxides contain carbon and oxygen which means that the fuel and oxygen are already present, which makes them powerful explosives such as ethyl ether.

Take Out Sign

CLASS 6.1 – Take Out Sign

These goods can cause harm to the human body and can include the likes of chlorinated hydrocarbons.

Infectious Substances

CLASS 6.2 – Infectious Substances

This can include pathogens that can cause infectious diseases in humans and animals such as Ebola Virus, Lassa Virus and the Rabies Virus.

Radioactive Substances

CLASS 7 –  Radioactive Substances

Radioactive substances contain unstable atoms which means that they could give off invisible radiation that can cause damage to the body.

Corrosive Substances

CLASS 8 – Corrosive Substances

These substances can be very dangerous if mixed together. This includes the likes of acids and alkalis and they can cause significant damage to the body.

Miscellaneous Dangerous Goods

CLASS 9 – Miscellaneous Dangerous Goods

Miscellaneous goods will include those that present a risk that is not covered by the other classes. An example of this might be a self-inflating life raft that contains compressed gas, explosive flares and flammable solid materials.

Why is it Important to Use The Correct Signage?

Each class differs which means that the risks between the goods also differ. What this means is that it is important to ensure that all of the goods are transported in accordance with the laws. This signage will clearly state what the materials are while it also makes it possible to identify the risks. As an example, corrosive materials can cause damage to many different materials while liquids that are flammable can ignite and cause significant damage.

As the risks can differ, it means that it is important that these materials are placed in the right dangerous goods storage as per their dangerous goods signage. This is because different controls are implemented to reduce the risk of the hazard and to maintain safety.

Examples are Lithium batteries or Elevated temperature Bitumen which is transported between 170 – 220 degrees range.

How to Choose The Right ADR Transport Company?

When it comes to choosing the right ADR transport company, it is important that they are fully aware of the European Agreements Concerning the International Carriage of Dangerous Goods. This means that they have the scope to understand the different goods, the signs, the risks and know how to transport these goods in line with laws and regulations. They should also have qualified drivers who are highly trained and the right vehicles for transporting the goods. The vehicles must meet certain specifications and conditions in order to be suitable, therefore, an experienced and reputable company will put everything in place to provide a first-class and safe service.

Driver Link Training provides the full range of ADR Training Courses for drivers involved in the transportation of Dangerous Goods. Find out more about our ADR Training modules.


It is important that the right signage is used when transporting dangerous goods. It is also vital that the company transporting the goods also understands the signs and risks. This highlights the importance of the correct training, so drivers are well-equipped and capable of delivering a service that meets all expectations.