What Is an ADR Warning Sign?

What Do Orange ADR Plates Mean?

An orange ADR plate means the vehicle carries dangerous goods above the ADR exemption thresholds. Emergency services, tunnel operators and roadside inspectors read the plate before they approach the load.

The standard plate is retroreflective and measures 400 × 300 mm with a 15 mm black border. Vehicles without enough surface area use a reduced plate of 300 × 120 mm with a 10 mm border. Plain orange plates with no numbers mark vehicles carrying packaged goods. Numbered plates mark tank vehicles and bulk loads, where the exact substance matters to first responders.

The orange plate is one of 6 dangerous goods entries in the logistics glossary, where the plate, the UN number and the packing group describe the same consignment from 3 angles.

What Do the Numbers on an ADR Plate Represent?

The numbers on an ADR plate represent the hazard and the substance. The top number is the hazard identification number, also called the Kemler code. The bottom number is the 4-digit UN number for dangerous goods that identifies the exact substance.

The Kemler code has 2 or 3 digits. The first digit shows the primary hazard, and the next digits show secondary hazards:

• 2: gas released by pressure or chemical reaction
• 3: flammable liquid or gas
• 4: flammable solid
• 5: oxidising effect
• 6: toxicity or risk of infection
• 7: radioactivity
• 8: corrosivity
• 9: risk of spontaneous violent reaction

A doubled digit means an intensified hazard, so 33 marks a highly flammable liquid. A zero after the digit means one hazard describes the substance fully, as in 30. The letter X before the code, as in X88, warns that the substance reacts dangerously with water.

A plate reading 33 over 1203 identifies petrol: a highly flammable liquid carrying the UN number assigned to motor spirit. The plate identifies the substance, while a second set of marks identifies the hazard class.

Hazard Placards and Other Vehicle Marks

A hazard placard is a 250 × 250 mm diamond fixed to tanks, containers and bulk vehicles to show the hazard class. Packages carry the same diamond as a 100 × 100 mm label.

Vehicles also display extra marks where the load requires them:

• The environmentally hazardous substance mark shows a fish and tree symbol.
• The limited quantities mark applies above 8 tonnes of limited quantity goods on a transport unit over 12 tonnes.
• The elevated temperature mark applies to substances carried hot.

Every one of these marks applies only above a legal load threshold in the ADR regulations.

When Are ADR Warning Signs Required?

ADR warning signs are required on every transport unit carrying dangerous goods above the small-load thresholds in ADR section 1.1.3.6. Loads within those thresholds, calculated on a 1,000-point scale per transport unit, travel without orange plates.

Plates stay on empty tank vehicles until the tank is cleaned, because residue still carries the hazard. Plates are covered or removed once the vehicle carries no dangerous goods or residue. Vehicle marking is the final step in a chain of ADR terminology that starts with classification and the safety data sheet.