Transport operations, supervision, mixed loading, segregation and security
Mixed loading
Chapter 7.5.2 prohibits loading certain dangerous goods together in one wagon or one container. The classic case is Class 1 explosives, which cannot share a wagon with flammable, oxidising or toxic goods except where the table allows; the table is asymmetric, so "A with B" may be forbidden while "B with A" is not, and the restriction operates at wagon and container level, not merely at package level. Segregation questions are usually answerable only by reading the table for both entries.
Supervision and parking
Wagons carrying high-risk goods must be kept under supervision or parked in designated secure sidings rather than left unattended on running lines or in open yards. Marshalling yards handling such traffic need controlled access, lighting and a nominated person responsible for the load while it stands.
Security (Chapter 1.10)
Chapter 1.10 applies to all dangerous goods: awareness of security risks, secure storage of documents, and personnel reliability. High consequence dangerous goods trigger the extra regime - Table 1.10.3.1.2 sets quantity thresholds, and above them the consignor, carrier and consignee must each have a security plan, a nominated security correspondent and enhanced training. For Class 1, any quantity falls inside the regime.
Worked example
Two thousand five hundred litres of UN 1090 ACETONE, Class 3, PG II. The high consequence table lists Class 3 at PG I only (3 000 L), so this load is not high consequence: no security plan is triggered. Chapter 1.10 general measures and secure parking still apply. Change the load to 3 500 L at PG I and the full plan requirement bites.
Traps
Assuming any dangerous goods load is high consequence; forgetting that thresholds are per class and packing group; treating segregation as a packaging question; leaving high-risk wagons unsupervised overnight.