Road Tunnels Manual
Dangerous goods or hazardous materials are solids, liquids or gases that can harm people, other living organisms, property or the environment, considering their chemical or physical properties. A substance or a material presenting a particular hazard should be used, handled or transported taking into account the characteristics of that hazard. A substance or a material is considered dangerous when it:
A dangerous good can present more than one kind of hazard and therefore several risks. The different types of hazard that may occur during road transport are coded as:
The following table describes hazards posed by dangerous goods depending on their Class according to ADR classification.
Class number |
Class description |
Hazard description |
---|---|---|
Class 1 |
Explosive substances or articles |
• may cause undesired uncontrolled explosion, • may cause gas expansion and generate blast wave, • may cause property and physical damage, • launch of fragments at high speed and long distances. |
Class 2 |
Gases |
• they may be flammable, • they may be oxidising or at risk of oxidation, • in enclosed and closed rooms it can cause asphyxiation without being perceived, • they may be toxic, • if they are under pressure they may cause rupture (with possible explosion of the container), • if they are refrigerated (cryogenic) they can endanger human tissues, or if the temperature of the container increases rapidly the pressure may cause an explosion; these gases may also be flammable. |
Class 3 |
Flammable liquids |
• cause of fire. |
Class 4.1 |
Flammable solids, self-reactive substances, polymerizing substances and solid desensitized explosives |
• flammability, |
Class 4.2 |
Substances liable to spontaneous combustion |
hazards of substances and articles of this Class are due to the possibility of their automatic ignition on contact with the air and without cause (spark or flame); on contact with oxygen they may self-ignite. |
Class 4.3 |
Substances which, in contact with water, emit flammable gases |
• creation of flammable gases, |
Class 5.1 |
Oxidizing substances |
• ignition, |
Class 5.2 |
Organic peroxides |
• easy ignition, |
Class 6.1 |
Toxic substances |
• danger to human health, |
Class 6.2 |
Infectious substances |
substances are hazardous because they contain micro-organisms (bacteria, parasites, viruses) that can cause infections in humans and animals; they may also contain bacteria, parasitic organisms or viruses without antidote in case of infection. |
Class 7 |
Radioactive material |
Hazards arising from the transport of contaminated radioactive substances
Radiation can affect humans externally or internally:
|
Class 8 |
Corrosive substances |
• damage to the skin, eyes, mucous membranes and tissue necrosis, |
Class 9 |
Miscellaneous dangerous substances and articles |
• hazard to health if they enter the respiratory system (asbestos) |