Dangerous Goods: Classes, Duties and Routing

Dangerous goods are goods that can harm people, property or the environment while they are being moved, handled or stored, and that therefore travel under transport rules of their own. They can be solid, liquid or gas. In freight talk the same idea goes by the name hazmat.

What makes a load dangerous is classification, not how it looks on the ramp. A pallet of aerosols, a drum of solvent, a crate of lithium batteries and a tank of fuel are ordinary cargo commercially and dangerous goods in transport terms. Once a substance is classified, the packaging, the marking, the paperwork and the vehicle follow from the classification, not from the booking mail.

The nine classes of dangerous goods

The international system sorts dangerous goods into nine hazard classes:

1. Explosives
2. Gases
3. Flammable liquids
4. Flammable solids and substances liable to spontaneous combustion
5. Oxidising substances and organic peroxides
6. Toxic and infectious substances
7. Radioactive material
8. Corrosive substances
9. Miscellaneous dangerous goods, the catch-all for hazards fitting none of the others

Inside a class, each substance carries a UN number and a proper shipping name. That pair is the identity of the goods in transport: what the packer reads when choosing packaging, what the driver's papers quote, and what an emergency crew reads off the vehicle. Many entries also carry a packing group, which grades the severity of the hazard within the class.

ADR is the European agreement for moving dangerous goods by road, with RID covering rail and ADN covering inland waterway. All three rest on the UN Model Regulations and share one classification system, so a load keeps its identity when it changes mode.

Why the route is part of the load

Dangerous goods change the road, not only the trailer. Tunnels are graded for what may pass through them, some roads and built-up areas are closed to certain classes, and there are rules on where a loaded vehicle may stand.

A route that suits a general cargo trailer can be wrong for the same trailer carrying hazardous freight, and the difference usually shows up as a detour. Working it out in the office is cheaper than discovering it with a loaded tank at a tunnel portal, so routing here belongs to dispatch, not to the driver alone. That is the thinking behind a dedicated ADR transport setup.

Who is responsible for what

Duties are split across the chain, and most arguments start where each party assumed the other had done the job. European law splits the rules too: dangerous-goods law covers movement and temporary storage, hazardous-materials law covers use and warehousing.

The shipper classifies the goods, declares them and provides correct documents. Packing and filling are duties in their own right: approved packaging, properly closed, marked and labelled. The carrier accepts the consignment, checks that what stands in front of the driver matches the declaration, and puts a trained driver and the required equipment on the road. The receiver has to be able to take the goods at the other end.

Above the small-quantity thresholds the driver needs an ADR training certificate of their own, and below them the load travels under lighter rules. Companies that carry, pack, load or unload these goods must appoint a dangerous goods safety adviser. Neither role replaces the duties above: the certificate and the adviser do not take the classification duty off the party that declared the goods.

What the transport papers have to say

A dangerous goods consignment travels with a description written in a fixed order, not in free prose: the UN number, the proper shipping name, the class, the packing group where one applies, then the number and kind of packages and the quantity carried.

Written instructions for the crew travel in the cab too, so the driver has something to act on in case of a leak, fire or spill. None of this sits apart from the file: it belongs with the consignment note and the delivery instructions on the transport order.

Before you accept a dangerous goods job

Ask for the classification in writing before you quote, not after you have promised a truck. The UN number and the class tell you which vehicle, which equipment and which driver you need, and whether the job is one your fleet should take.

Then check both ends of the journey. Some sites take hazardous deliveries only in set windows, some insist on their own escort across the yard, and some turn a driver away over a marking that cost nothing to fix at loading.

Finally, agree what happens when the load is not as declared. If the drums are marked differently from the paperwork, the driver needs to know in advance whether to load, refuse or call dispatch. A dangerous goods job goes wrong quietly, in a description nobody checked, long before it goes wrong loudly on the road.