What your freight goes through

Packaging advice makes a lot more sense once you know what it is protecting against. An LTL trailer is a shared space, so your pallet spends the trip surrounded by other people's freight, and it gets picked up and put down repeatedly along the way. These are the forces at work.

The four hazards

Almost all freight damage traces back to one of these four:

• Shock. Sudden impacts. Speed bumps, potholes, hard braking, and being set down by a forklift.
• Vibration. Constant, low-level shaking that is present for essentially the whole time the truck is moving. It works fasteners loose, wears through packaging by abrasion, and lets contents settle.
• Compression. Weight pressing down from above, plus the squeeze from straps and stretch film. This is the force most people underestimate.
• Exposure. Temperature and humidity swings, dust, dirt, odors, and condensation. Cardboard in particular gets dramatically weaker when it is damp.

Compression: the freight stacked above yours

Trailers get loaded to fill space, which is how LTL keeps costs down. If there is room above your pallet, something goes there. The amount of weight that can end up on top of your freight is a direct function of how much empty space you leave between the top of your load and the trailer ceiling.

Two practical consequences:

• Fill the vertical space where you can. If the product can safely ship standing up rather than lying flat, it usually should. Just watch the height-to-base ratio below, and remember that both orientations change the dimensions on your quote.
• Assume something will be stacked on you. Road hazards create short bursts of compression that can reach five times the weight of the freight above, so a box rated only for its own static load is not enough.

If your freight genuinely cannot take any weight on top, that is a stackability question rather than a packaging one. Mark it as not stackable when you quote, because it changes how much trailer space the carrier has to sell you. See Shipment Contents.

Top-heavy freight, the most common failure

When a truck turns a corner, the freight resists the change in direction. A tall, narrow load has very little leverage to resist with, so it tips or leans onto whatever is next to it. The useful rule of thumb compares the height of the load to the smallest dimension of its base, which is usually the pallet width.

If your load lands in the unstable zone, you have three options:

1. Use a bigger pallet

   Widening the base is the cleanest fix, because it changes the ratio rather than compensating for it. A 48 x 48 pallet instead of a 48 x 40 buys real stability.

2. Split the load

   Two shorter handling units are far more likely to arrive intact than one tall one, and they are usually easier to handle at both ends.

3. Package for the stabilization it will get

   Carriers stabilize tall freight with cargo straps, shoring beams, adjacent freight, and the trailer wall. Those methods concentrate force on the corners and edges of your load, so it needs reinforced corner protection to take them. See Stacking and securing the load.

Why "it survived last time" is not a plan

The number of times freight is handled varies by route. A shipment that moves direct between two terminals gets handled far less than one that transfers through two or three, and interlined shipments change carriers along the way. You do not control which route your shipment takes, so the packaging has to be good enough for the worst realistic case. See Interlining and How Freight Moves.