Intermodal Transport Units Explained: Pallets, Containers, and Everything Between

Let's dive into the different containers we see in intermodal transport.

Michael Keith Lewis
Michael Keith Lewis
Intermodal Transport Units Explained: Pallets, Containers, and Everything Between

Intermodal transport sounds abstract until you’re the one staring at a dock, a booking deadline, and a pile of freight that almost fits. At its core, intermodal just means moving goods using multiple modes of transport (truck, rail, ship) without handling the cargo itself between modes. What makes that possible is standardization: pallets, containers, and unit load devices that behave predictably across borders and vehicles.

This guide breaks down the most common pallets, containers, and transport units used in intermodal logistics, what they’re good at, and where people get burned when they choose the wrong one.

1. Pallets: The Atomic Unit of Freight

Pallets are the smallest standardized building block in intermodal logistics. Everything else scales up from here.

Common Pallet Types

🇺🇸 GMA / North American Pallet (48” × 40”)

  • Where used: U.S., Canada
  • Why it exists: Designed to fit efficiently in domestic trailers and 40’ containers
  • Reality check: Slight inefficiencies when mixed with Euro pallets or used in air freight

🇪🇺 Euro Pallet / EUR‑1 (1200mm × 800mm)

  • Where used: Europe
  • Strength: Excellent modularity in European trucks and warehouses
  • Tradeoff: Suboptimal in ISO containers unless planned carefully

Half & Quarter Pallets

  • Use case: Retail, mixed SKUs, last‑mile delivery
  • Gotcha: High cube waste if you don’t re‑stack upstream

Pallet Materials

  • Wood: Cheap, repairable, heavy, ISPM‑15 compliance required internationally
  • Plastic: Consistent dimensions, lighter, expensive
  • Metal: Niche, extreme durability, heavy
  • Cardboard / Composite: One‑way shipping, fragile

Skeptical takeaway: pallets feel standardized until you mix regions. That’s where density and wasted air quietly kill margins.

2. Unit Load Devices (ULDs): Air Freight’s Version of Pallets

Air freight doesn’t use pallets the way surface transport does. Instead, it uses ULDs, which are shaped to the aircraft.

Common ULD Types

  • AKE / LD‑3: Half‑width containers used on wide‑body aircraft
  • PMC / PLA: Flat pallets with contour nets
  • Lower‑deck vs Main‑deck: Completely different constraints

Why ULDs Matter

  • Aircraft balance and contour matter more than raw volume
  • Over‑dimensioning here means you don’t fly at all
Forward‑thinking note: air freight is unforgiving. If your upstream pallet strategy ignores ULDs, you pay for it later…literally by the kilo.

3. ISO Shipping Containers: The Backbone of Intermodal

These are what most people think of when they hear “container.” But not all containers behave the same.

Standard Dry Containers

20’ Container

  • Best for: Heavy, dense freight
  • Typical reality: Weight‑limited before volume‑limited
  • Common mistake: Leaving cubic capacity unused

40’ Container

  • Best for: Palletized consumer goods
  • Sweet spot: Standard global freight

40’ High Cube (HC)

  • Extra height: ~1 ft more vertical clearance
  • Why it matters: Double‑stacked pallets suddenly become viable
From experience: most people under‑estimate height before they under‑estimate weight.

Specialized Containers

Refrigerated (Reefer)

  • Temperature‑controlled
  • Reduced usable interior space
  • Power availability matters more than people expect

Open‑Top / Flat Rack

  • Over‑height or over‑width cargo
  • Expensive insurance, expensive mistakes

4. Intermodal Rail Units

Rail introduces its own abstractions.

Common Rail Equipment

  • Well Cars: Designed to stack containers double‑high
  • 53’ Domestic Containers: North America only
  • Intermodal Chassis: The silent bottleneck in many supply chains
Hard truth: you don’t really book rail, you book availability of everything around rail.

5. Truck Trailers (Because Reality Is Messy)

Even in intermodal workflows, trucks do the first and last mile.

Common Trailer Types

  • Dry Van (53’): Domestic U.S. workhorse
  • Step Deck / Lowboy: Height‑restricted freight
  • Curtain‑Side: Fast access, limited structural support

Mismatch between pallet strategy and trailer geometry is one of the most common, least talked‑about inefficiencies.

6. The Real Problem: Interfaces

Most logistics failures don’t happen inside a pallet or container. They happen at the interface:

  • Pallet → Container
  • Container → Rail
  • Rail → Truck

Each interface introduces constraints that upstream decisions often ignore.

Skeptical rule of thumb: if you didn’t model it, you’re paying for it.

7. Why This Matters More Than Ever

Rising fuel costs, tighter margins, and global labor constraints mean inefficiency is no longer invisible. What used to be “good enough” is now measurable waste.

Forward‑thinking operators are:

  • Planning loads digitally before freight ever moves
  • Choosing containers based on actual usable volume, not marketing specs
  • Treating pallets as design decisions, not defaults

Final Thought

Intermodal transport works because standards exist but profit lives in the gaps between those standards. Understanding pallets, containers, and transport units isn’t academic. It’s how you stop shipping air.

If you’re serious about logistics optimization, the next step isn’t a bigger container. It’s better planning.