Ask how long produce spends in transit and the answer is usually the driving time. Add the dwell – the hours a loaded crate sits on a dock, in a yard, or in a trailer with the unit off before it departs – and the total is often double. Dwell is where the field heat does its work, and it is the part of the cold chain that nobody owns.
Where dwell accumulates
Four places. Waiting for the paperwork and the load sheet. Waiting for a trailer that is late. Sitting in a yard in the sun because the unit is not running until departure. And sitting at the receiving end before unloading starts. Each is an hour or three, and each happens at the warmest point in the day more often than not.
What the produce is doing meanwhile
Respiring. A crop picked at 28C and held at 28C for six hours loses shelf life at a rate that no amount of subsequent cooling recovers. The cooling that happens later removes the heat; it does not give back the time. This is why pre-cooling close to the field matters more than the temperature in the trailer, and why the crate should be part of the pre-cooling strategy rather than waiting at the end of it – see crates for pre-cooling after harvest.
How a crate helps and where it does not
A vented crate in a running refrigerated trailer cools a stack faster than a carton does, so it reduces the recovery time after a dwell period. What it cannot do is cool anything while the unit is off and the trailer is in the sun – in that situation a stack of crates in a closed box is an oven, vented or not. The fix for dwell is scheduling and shade, not packaging.
What to measure
Put a timestamp on four events: packed, loaded, departed, arrived. The gap between packed and departed is the number nobody knows and the one that is usually largest. A season of that data changes how the site schedules, and it is cheap to collect because it needs no instrumentation – just someone writing down times.
Practical changes that work
Pre-cool before the crate goes on the truck rather than expecting the trailer to do it. Stage loaded crates in shade, not in the yard. Run the refrigeration unit while loading rather than after. And sequence the load so the last-on produce is not the first-off, so nothing sits at the back through two unloading stops. None of these cost money; all of them need a decision.
Where the crate choice does matter
If dwell is unavoidable, stacking strength at temperature matters, because a stack sitting in a warm trailer before cooling will be softer and the produce will settle. A crate does not soften, which removes one variable. The other variable – the produce itself – is not something packaging can fix, and it is worth being honest about that boundary.
Who should own the number
Dwell falls between packing, transport and receiving, so nobody owns it. Naming one person – usually whoever plans the loading schedule – is the single intervention that reduces it, because the measurement then happens and someone is accountable for what it shows.
The measurement itself is four timestamps written on a load sheet. Once they exist for a few weeks, the pattern is usually obvious: a particular loading window, a particular haulier, or a receiving point that always takes two hours. Fixing one of those is worth more than any packaging change.
What we can do
We supply vented produce crates that stack at full height warm and cool a stack quickly once the unit runs. Tell us the crop, the realistic dwell and whether pre-cooling happens before loading, and we will advise on the vent pattern and stack height.