ADR 2025 1.9.5 and 8.6
Tunnel Restrictions
Decode the exact tunnel restriction code forms and compare them with the GB tunnel directory.
How this is calculated
How tunnel restriction codes are read
A tunnel restriction code names the most permissive tunnel category the load may not pass through, and every more restrictive category with it. Tunnel categories run from A, the least restrictive, to E, the most restrictive, so a code of C means passage is forbidden through categories C, D and E.
The codes come in three shapes: a single letter, a mass-qualified code, and a carriage-mode code written with a slash. A dash means no tunnel restriction applies.
- 1
Single letters B, C, D and E
Read the letter, then include everything after it in the sequence. E forbids only category E; B forbids B, C, D and E.
- 2
Mass-qualified codes B1000C and C5000D
The number is a net explosive mass threshold. B1000C forbids B, C, D and E above 1,000 kg, and C, D and E at or below it. C5000D forbids C, D and E above 5,000 kg, and D and E at or below it.
- 3
Carriage-mode codes with a slash
The letter before the slash applies to tank carriage — and to bulk as well in the case of D/E — while the letter after it applies to other carriage. C/E forbids C, D and E in tanks, and only E otherwise.
- 4
A dash means no restriction
Passage is allowed through all tunnel categories on the basis of the code alone.
Worked example
A load with tunnel restriction code B/E, carried in packages.
- B applies to tank carriage: categories B, C, D and E
- E applies to other carriage: category E only
- This load is in packages, so the second half applies
Result: Passage is forbidden through category E tunnels only. A category C tunnel is not restricted by this code for this carriage mode.
What this tool does not decide: Decoding the code is not a route decision. Which category a given tunnel holds, what signage applies and whether a route is permitted are separate questions, governed by the current GB tunnel category list and the responsible duty holder.
Carry ADR Driver Pro with you
Revise by route, use the offline reference and keep practical driver tools close at hand.
