Altor guide · 2026-09-16

Multimodal journeys: when a shipment must satisfy two rulebooks

The carton left the dock on a truck. The aircraft accepted it. The vessel terminal sent it back. Same UN number. Same fibreboard. The second book was never opened.

A multimodal journey is not a courtesy copy of the first declaration. Each leg has its own acceptance. 49 CFR 173.22 still puts classification, description, packaging, marks, and labels on the offeror for every mode that carton will see.

What the regulation actually requires

49 CFR 171.22 authorizes a US shipper to offer hazardous materials in accordance with the ICAO Technical Instructions and the IMDG Code, with conditions. Using those books does not drop the Hazardous Materials Regulations. 171.22(b) requires conformance with the international standard you chose and with Part 171 Subpart C. 171.22(g) still keeps Part 172 Subpart G emergency response information and Part 172 Subpart H training.

49 CFR 171.24 is the ICAO overlay. An aircraft movement, and the highway or rail legs before or after it, must still meet Parts 171 and 175, the ICAO quantity limits, and any United States variation. 171.24(c) still wants the motor vehicle placarded under Part 172 Subpart F.

49 CFR 171.25 is the IMDG overlay. You may use the IMDG Code for vessel, and for motor or rail, only when all or part of the movement is by vessel. 171.25(b)(1) still points the water carriage to Part 176, and the highway or rail legs to Parts 177 or 174, with HMR placards on the vehicle. 49 CFR 176.24 will not accept the freight without a shipping paper prepared under Part 172 or authorized by Part 171 Subpart C.

The documents are not interchangeable. IATA DGR 8.1 is the air Shipper's Declaration. IMDG Code 5.4.1 is the sea transport document. IMDG Code 5.4.2 is the container or vehicle packing certificate, signed by the person who packed the container, not by whoever filled the air form. 49 CFR 172.202 is the HMR basic description. For water, 172.203(i) adds the shipper's name and, for a Class 3 flammable liquid with a closed cup flash point of 60 C (140 F) or below, that flash point next to the basic description. 49 CFR 172.204 and IATA DGR 8.1.6.12 are still certifications by the person who offers the material.

A worked air and water example from the current ICAO extract. UN 1845, Dry ice or Carbon dioxide, solid, Class 9, no packing group. Packing instruction 954 at 200 kg passenger and cargo. 49 CFR 172.101 prints A and W for this entry, so the HMR applies when the material is offered by aircraft or by vessel. Column 6 is none, which is why a highway carton often has no diamond. 49 CFR 173.217(a) still requires packaging that can release carbon dioxide gas. 173.217(b)(1) requires each transport vehicle and freight container containing solid carbon dioxide to carry the dry ice warning mark on two sides. 173.217(b)(2) requires other packagings to be marked that they contain carbon dioxide, solid, and must not be stowed below decks. Those vessel marks are not packing instruction 954.

A second line. UN 1090 Acetone, Class 3, packing group II. Passenger packing instruction 353 at 5 L, limited quantity Y341 at 1 L, cargo packing instruction 364 at 60 L. The air desk walks IATA DGR 9.1.3 and 49 CFR 175.30. The water paper still needs the 172.203(i) flash point when it is 60 C or below. A highway limited quantity carton under 49 CFR 173.150 is not an air limited quantity under 173.27(f)(2), and it is not an IMDG limited quantity by inheritance.

UN 3480 Lithium ion batteries is passenger forbidden on the air list. When those cells move under IMDG special provision 188, 49 CFR 171.25(b)(3) still wants the passenger aircraft forbidden mark, or a Cargo Aircraft Only label under 172.448, on the package.

The mistake people make

Desks pack once, to the book on the shelf. They photocopy the IATA Shipper's Declaration onto an ocean booking and call it multimodal. They never get a container packing certificate. They treat dry ice as unregulated because the truck did not care, then load the same cooler in a freight container with no 173.217(b) marks. They skip the flash point on UN 1090 because the air form never asked for it that way. They offer a highway limited quantity diamond, no Y, to an aircraft, then to a vessel.

Packing to the stricter inner packaging is not a complete rule. You can meet the tighter quantity cap and still miss a mode-specific mark or a second signature. The second terminal grades that mode's book. Disagreement parks the freight. What to do after a rejection sits at https://altor.consulting/rejected.html.

How to fix it

Write every mode on the routing before anyone tapes a diamond. If the carton will see an aircraft, open the current IATA DGR Section 4.2 list and packing instruction, plus 49 CFR 171.24. If it will see a vessel, open the current IMDG Dangerous Goods List and 49 CFR 171.25. Pack so every leg is legal.

For UN 1845, vent the packaging and apply the 173.217(b) vessel marks when water is on the routing, plus the air marks and miscellaneous Class 9 label when the booking is an aircraft. For UN 1090, lock packing group II and the quantity against packing instruction 353, Y341, or 364, then put the closed cup flash point on the water shipping paper when 172.203(i)(2) applies. Complete IATA DGR 8.1 for air. Complete IMDG 5.4.1, and 5.4.2 when goods are packed in a container or vehicle. Walk IATA DGR 9.1.3 and 49 CFR 176.24. If you cannot stand behind every leg under 49 CFR 172.204, fix the carton and the paper, then sign.

Do not offer a one-mode carton on a two-mode routing.

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