ADR explained: the nine classes of dangerous goods and the paperwork that goes with them
Nine classes, the driver’s document set, vehicle equipment and the exemptions people most often get wrong. Not a rewrite of the agreement, just what a roadside inspection actually checks.
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What ADR is
ADR is the international agreement covering the carriage of dangerous goods by road, concluded under the UN Economic Commission for Europe. It applies across Europe and in a number of countries beyond it, and the text is revised every two years, which is why people always name an edition, such as ADR 2025.
The agreement does not ban dangerous goods. It sets out the conditions under which moving them is lawful: how to classify, pack, mark and label them, what paperwork to carry and how to equip the vehicle.
The nine classes
Classification starts with the UN number, the four-digit identifier of the substance. That number, not the trade name, drives everything else.
| Class | What it covers | Typical cargo |
|---|---|---|
| 1 | Explosives | ammunition, pyrotechnics |
| 2 | Gases | LPG, oxygen, argon, aerosols |
| 3 | Flammable liquids | petrol, solvents, paints, alcohol |
| 4.1 / 4.2 / 4.3 | Flammable solids, self-heating, water-reactive | sulphur, activated carbon, carbide |
| 5.1 / 5.2 | Oxidisers and organic peroxides | nitrogen fertiliser, hydrogen peroxide |
| 6.1 / 6.2 | Toxic and infectious substances | pesticides, medical samples |
| 7 | Radioactive material | medical isotopes, measuring devices |
| 8 | Corrosives | acids, alkalis, battery electrolyte |
| 9 | Miscellaneous dangerous goods | lithium batteries, dry ice, asbestos |
What the driver must carry
- Transport document showing the UN number, proper shipping name, class, packing group and quantity per transport unit.
- Instructions in writing - the four-page format from ADR 5.4.3, in a language every crew member can read.
- ADR driver training certificate - valid five years, with separate entitlements for tanks and for classes 1 and 7.
- Vehicle approval certificate - required for tanks, explosives vehicles and certain other cases.
- Photographic ID for every crew member.
Vehicle equipment
Fire extinguishers sized by the vehicle’s gross weight, a wheel chock, two self-standing warning signs, a high-visibility vest, a torch with no exposed metal, gloves and eye protection for each crew member, plus whatever the written instructions require for the class carried, eye-rinsing liquid with corrosives, for example.
Marking: orange plates front and rear, and on tanks the hazard identification number above the UN number. Add the hazard labels on the load unit and the tunnel restriction code, which decides which tunnels the vehicle may use.
The exemptions people get wrong
- Limited quantities (LQ). Goods in small inner packagings can travel outside the full ADR regime, but the LQ marking and the mass limits per transport unit still apply.
- The 1.1.3.6 rule - the “1,000 points” calculation. Below the threshold for the transport category some requirements fall away, but the transport document and the extinguisher do not.
- The private-use exemption covers genuinely narrow situations and effectively never applies to carriage for hire or reward.
The most common mistake in practice is assuming that small packaging means ADR does not apply at all. It does apply, in reduced form.
Safety adviser, and the Polish overlay
Any undertaking whose activity involves dangerous goods must appoint a dangerous goods safety adviser (DGSA) and file an annual report. That duty sits with the consignor and the carrier, not the driver.
In Poland a share of ADR loads also falls under the SENT monitoring system, fuels, solvents and waste in particular. Both regimes then apply at once: a PUESC declaration alongside the full ADR document set. See our article on the SENT system.
How we handle it
We classify the load by UN number before accepting the order, match the vehicle and a driver with the right entitlements, and prepare the document set. Scope is set out under dangerous goods transport, with tanks covered in tanker transport.
Frequently asked
Is every chemical an ADR load?
No. Classification and the UN number decide, not the product name. A good many substances sit outside the agreement.
How long is a driver’s ADR certificate valid?
Five years, renewable after a refresher course.
Can the instructions in writing be in English only?
They must be in a language each crew member reads. If the driver has no English, an English copy is not enough.
What happens if the transport document is missing?
The vehicle is held until it is produced, and a penalty falls on both carrier and consignor.