8.2 Tunnel Restriction Categories (A through E) and Passage Rules

Tunnel category and load code are different things

ADR 1.9.5 allows competent authorities to assign tunnel categories reflecting the consequences of dangerous goods incidents and available alternatives. Chapter 8.6 then connects those categories to the goods’ tunnel restriction codes. A driver needs both the signed tunnel category and the code for the whole load. The class number alone is insufficient.

Category A has no dangerous-goods restriction under this system. Categories B, C and D progressively restrict goods capable of very large explosions, large explosions/toxic releases, and large fires. Category E is the most restrictive. These are common ADR categories, while other road restrictions and operational directions can still apply. “Category A” does not cancel a weight limit, closure, police direction or other applicable traffic rule.

ADR 8.6.2 shows no dangerous-goods tunnel sign for category A and a sign with the relevant letter panel for B–E. It does not state that every sign without a letter automatically makes a tunnel category E. Resolve unclear signage or route instructions before entering; do not invent permission from a missing panel.

Read Table A column (15), then the exact 8.6.4 row

The tunnel code is shown in parentheses in column (15). Where required, it appears on the transport document after the dangerous goods description. A packaging code, transport category or HIN is not a tunnel code.

The D/E distinction is crucial: bulk goes with tanks in that row. It is incorrect to teach “first letter tanks, second letter packages and bulk” as a universal rule. Bulk means goods carried without the individual packages that would make them packaged carriage; an IBC remains a package, not a small tank merely because it holds a large quantity.

There are also quantity-dependent explosives codes. B1000C uses B–E when net explosive mass exceeds 1,000 kg and C–E when it does not. C5000D uses C–E when net explosive mass exceeds 5,000 kg and D–E when it does not. These quantities mean net explosive mass, not the gross weight of cartons or pallets. A basic driver recognises that these codes require the exact authorised explosives load calculation and specialist conditions.

Worked passage decisions

Petrol UN 1203, code D/E, tank carriage: use the bulk/tank branch, so passage is prohibited in D and E and allowed by this table in A–C. The same goods in drums use the other-carriage branch and are restricted in E. The driver must still check that the total load and actual operation are lawful.

Bulk goods with an assigned D/E code: use the D/E bulk/tank branch, even though there is no fixed road tank. Treating the load as “other carriage” would wrongly permit a category D tunnel.

Mixed packaged load: one relevant consignment has effective restriction E and another D. The whole load must satisfy the more restrictive condition, D. Do not average letters, choose the largest pallet or let a low-hazard load cancel a stricter item. Apply each code’s quantity/mode conditions before comparing restrictions. Goods carried under the relevant exemptions are handled as specified in 8.6.3.3.

A dash: UN 3082 provides a familiar example of an entry without a tunnel restriction. Do not infer that diesel in drums automatically has a dash: UN 1202 has its assigned code, and package carriage must be interpreted through that row. A dash for one product does not neutralise another product’s restrictions.

Exemptions and the limited-quantity trap

Dangerous goods carried under 1.1.3 are generally not subject to the tunnel restrictions and are excluded from determining the whole-load code, subject to the LQ marking exception in 8.6.3.3. A qualifying 1.1.3.6 small-load operation is therefore different from a fully regulated orange-plated load.

LQ is not always unrestricted. Chapter 8.6.4 restricts transport units requiring the LQ marking under 3.4.13, subject to 3.4.14, in category E tunnels. A transport unit over 12 tonnes maximum permissible mass carrying more than 8 tonnes gross mass of LQ packages can therefore be barred from an E tunnel even though it does not need orange plates. The 8-tonne measure is gross mass of the LQ packages, not net dangerous substance or vehicle tare. The table’s note also addresses IMDG-marked LQ units: the specified E-tunnel relief applies when the LQ package gross mass does not exceed 8 tonnes per transport unit.

Driving behaviour and emergencies inside tunnels

Plan the route before departure and confirm the latest operator restrictions, closures and any required booking or escort arrangements. Check the correct approach route and diversion before reaching the last safe exit. Do not stop in a traffic lane to argue with the signs or use ordinary satnav directions as permission.

Drive smoothly, observe the tunnel’s signals and spacing instructions, and avoid unnecessary stops. If breakdown or fire occurs, use the tunnel operator’s posted emergency directions, alert emergency services and identify the dangerous goods. Secure the vehicle only where safe, avoid smoke and move to a signed safe exit as directed. Do not turn around, reverse against traffic, return for documents through smoke or open the cargo to investigate a fire. The tunnel emergency plan and responders determine evacuation; ADR does not give one universal safe distance or driver firefighting tactic for all tunnels.

Source check: 17 October 2026 — ADR 2025, English text published by the Slovak Ministry of Transport, 1.9.5 and 8.6.