Loading, segregation & quantity thresholds

Some hazards must not travel together. The ADR 7.5.2.1 table, keyed on the danger labels, tells you which label combinations are prohibited or need separation; explosives have extra compatibility-group rules. Certain goods must also be kept away from foodstuffs. The DGSA verifies the firm applies the table correctly and, crucially, treats any unlisted/blank combination as prohibited rather than assuming it is allowed — the same fail-safe DGMind's segregation engine uses.

7.5.2.1 mixed-loading table is keyed on the danger labels.

ADR 1.1.3.6 lets a transport unit carry limited amounts before the full requirements (orange plates, ADR driver certificate, some equipment) apply. Each UN entry sits in a transport category (0–4) with a maximum quantity per transport unit. When goods of different categories are mixed, you multiply each quantity by a factor (category 1 ×50, category 2 ×3, category 3 ×1; category 0 = never exempt; category 4 = no limit) and the total must not exceed 1000. This calculation is a classic exam question — DGMind's quantity calculator does the same maths, but the candidate must show the working.

Each entry has a transport category 0–4 (Table A column / 1.1.3.6.3).

Real exam questions usually mix three or four items in different categories. The disciplined method: (1) write each item with its UN number, quantity and transport category from Table A; (2) write the multiplier (50/3/1/0/no-limit) next to each; (3) compute (qty × multiplier) per line; (4) sum; (5) note any category-0 item (the whole exemption is disqualified, you stop the calculation and say full-ADR); (6) state the verdict in one sentence with the citation. Worked example: 80 L cat 3 + 50 L cat 2 + 5 kg cat 1 + 0 cat 4 = (80×1) + (50×3) + (5×50) + 0 = 80 + 150 + 250 = 480 ≤ 1000 → within. If you had added 1 kg of a cat-0 item, the exemption would be disqualified regardless of the sum.

Tabulate every item with category and multiplier — show the working.

For Class 1 explosives, the 7.5.2.1 mixed-loading table is only half of the answer. The other half is the compatibility group letter (A–S) on each item: 7.5.2.2 sets which Class 1 groups may travel together and which may not. As a rule, items of the SAME group may load together; items of DIFFERENT groups need the 7.5.2.2 table — many combinations are prohibited, some are allowed if the load is a single division code (1.4S etc.), and rocket motors / detonators with main charges have specific rules. The DGSA must read the UN classification code (e.g. '1.1D', '1.4S') not just the class number.

Read the full Class 1 code: division (1.1–1.6) + compatibility group letter (A–S).

Mixed-loading and threshold maths don't help if the load shifts in transit. ADR 7.5.7 requires packages and containers to be secured by suitable means (lashings, dunnage, locking pins, friction mats) so they cannot move significantly during normal carriage. Stacking limits are observed; fragile packages are not crushed; orientation arrows are respected. The DGSA monitors that loading staff are trained in securing and that the securing equipment is available and in good order — load-shift is a frequent root cause of incidents and a typical roadside-check finding.

Secure packages so they cannot move significantly (7.5.7.1).