Dangerous goods road transport is regulated by ADR, updated biennially (ADR 2025 edition in force from 1 January 2025, mandatory from 1 July 2025). Key points: 9 hazard classes; each substance has a UN number and packing group (I=high, II=medium, III=low risk); certified UN-marked packaging required; vehicles must display orange panels and hazard placards; drivers need an ADR certificate (valid 5 years); every company shipping dangerous goods must appoint a Dangerous Goods Safety Adviser (DGSA); shippers must prepare ADR transport documents. ADR 2025 updates: new UN numbers for sodium-ion batteries (UN 3551/3552) and battery-powered vehicles (UN 3556-3558). Limited quantities (LQ) and excepted quantities benefit from partial exemptions. IMDG Code applies for sea transport, IATA-DGR for air.