Created On
February 1, 2024

What do HGV Signs and Symbols Mean?

What do HGV Signs and Symbols Mean?

When you see a lorry on the road, do you know what it is carrying? Lorries come in all different shapes and sizes, and each one has a special purpose. In this blog, we'll take a look at some of the different types of lorry found on UK roads as well as explain the signs and signals that can be seen around the vehicle.

It is a legal requirement for lorries on UK roads to display signage depending on the type of goods that it is transporting, or different markings around the vehicle depending on the weight or size of the vehicle.

Large Vehicle Rear Markings

Vehicles that are either 7,500Kg gross weight or more, and trailers that are over 3500Kg gross weight or more must display red and yellow large goods vehicle rear markings.

These markings are also required to be fitted to commercial vehicles longer than 13 meters, as well as skips that are placed on public roads.

Hazardous Warning Plates

Certain tank vehicles are required to display hazardous goods warning panels to display the types of dangerous goods that they are carrying. Each 'type' of hazardous material is assigned a class ranging from 1 to 9.

There are some key abbreviations to note for Hazardous Warning Plates:

EAC - Emergency Action Code (also known as hazchem)

ADR - Accord européen relatif au transport international des marchandises dangereuses par route, which in English translates to: "The European Agreement concerning the International Carriage of Dangerous Goods by Road".

HIN - Hazard Identification Numbers

In the UK, EAC codes must be used. This system of marking must not be confused or combined with the international ADR marking, which instead uses Hazard Identification Numbers (HIN), which are also known as Kemler/Kemmler codes.

The EAC code is a three-character code that must be displayed on all GB registered road vehicles that are carrying dangerous goods on public roads throughout the UK.

A hazardous warning plate should display the Emergency Action Code (EAC) which is also known as 'Hazchem Codes' and is used to provide a quick assessment to emergency services as to what actions should be taken during an accident. Emergency services use specific characters and numbers to determine which actions need to be made during the first few minutes of an incident involving dangerous goods.

The plate below shows the EAC code in the top section and the UN Number (which identifies the substance) at the bottom. The plate may also contain a phone number as well as a warning sign relating to the type of hazardous material (such as corrosive, or explosive).

Diamond Hazard Symbols

Explosives (Class 1)

The explosive class of hazardous goods is a marking for explosives, substances and articles such as fireworks. The explosives symbol is always displayed on an orange diamond sign. Class 1 explosives are sub-categorised into different classes (1.1 through 1.6) which further assigns types of explosives. For example, class 1.1 is for substances and articles that have a mass explosion hazard while class 1.6 is for extremely insensitive articles which do not have a mass explosion hazard.

Gasses (Class 2)

Gasses come in three forms; Flammable gasses, non-flammable gasses and toxic gasses, each with their own class (2.1, 2.2 and 2.3). Gasses include substances like propane, oxygen or carbon dioxide.

Flammable Liquids (Class 3)

Flammable liquids need to be transported by specially trained drivers with advanced qualifications in transporting flammable liquids, such as petrol or other fuels. Liquids are considered flammable when they have a flashpoint of below 61°C, meaning liquids that are at temperatures below 61°C will give off vapours that can be easily ignited by a spark, naked flame or heat.

Flammable Solids (Class 4)

Flammable solids are categorised into three subclasses 4.1, 4.2 and 4.3 which relate to readily combustible solids that may ignite through friction or self-reactive substances, those that are liable to spontaneously combust when they come into contact with air and finally those that combust or become flammable when they come into contact with water.

Oxidising & Organic Peroxide (Class 5)

Oxidising & Organic Peroxide substances are classified into 5.1 and 5.2 which are materials or substances that intensify the risk intensity of fires by fueling large quantities of oxygen which increases fire. Oxidising substances can become readily combustible when mixed with organic material, such as ammonium nitrate fertiliser or organic peroxides.

Poison (Class 6)

Classes 6.1 and 6.2 refer to poisonous substances which are liable to cause death or injury to humans if ingested, inhaled or by skin contact with toxic vapours, dust, granules or liquids. Poisonous substances can also be considered those that are infectious like bacteria, viruses, parasites or fungi.

Radioactive (Class 7)

The Class 7 substance relates to radioactive material like uranium. Depending on the type of radioactive material being transported, it may be necessary for a police escort.

Corrosive (Class 8)

Corrosive substances can be in the form of solids or liquids and are materials and vapours which damage living tissue on contact and can seriously damage metals and other materials. Corrosive substances can also usually react violently with water and so should be carefully disposed of in the event of an incident. Sulphuric Acid is an example of a corrosive class 8 substance used in haulage.

Miscellaneous (Class 9)

Miscellaneous substances are misc dangerous substances and articles which present a danger during transport that is not necessarily represented our outlined by another category, such as asbestos which is hazardous to the environment.

Reference: Images from and

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