The potential harm caused by some dangerous goods is amplified when transported through a tunnel. A Tunnel Restriction Code indicates the classes of tunnels that a vehicle containing such a substance can pass through, and in what quantities (if applicable).

Code Restriction
B Passage forbidden through tunnels of category B, C, D and E
B1000C Carriage where the total net explosive mass per transport unit
  • exceeds 1000 kg: Passage forbidden through tunnels of category B, C, D and E;
  • does not exceed 1000 kg: Passage forbidden through tunnels of category C, D and E
B/D Tank carriage: Passage forbidden through tunnels of category B, C, D and E;
Other carriage: Passage forbidden through tunnels of category D and E
B/E Tank carriage: Passage forbidden through tunnels of category B, C, D and E;
Other carriage: Passage forbidden through tunnels of category E
C Passage forbidden through tunnels of category C, D and E
C5000D Carriage where the total net explosive mass per transport unit
  • exceeds 5000 kg: Passage forbidden through tunnels of category C, D and E;
  • does not exceed 5000 kg: Passage forbidden through tunnels of category D and E
C/D Tank carriage: Passage forbidden through tunnels of category C, D and E;
Other carriage: Passage forbidden through tunnels of category D and E
C/E Tank carriage: Passage forbidden through tunnels of category C, D and E;
Other carriage: Passage forbidden through tunnels of category E
D Passage forbidden through tunnels of category D and E
D/E Bulk or tank carriage: Passage forbidden through tunnels of category D and E;
Other carriage: Passage forbidden through tunnels of category E
E Passage forbidden through tunnels of category E
- Passage allowed through all tunnels (For UN Nos. 2919 and 3331, see also 8.6.3.1).
ADR European Agreement Concerning the International Carriage of Dangerous Goods by Road, ECE/TRANS/257 (Vol. 1), Economic Commission for Europe Inland Transport Committee, UNECE 2017