A freight invoice is written against distance; in the cold chain the cooled volume is cooled whether or not there is product in it. According to Eurostat, about one fifth of EU road freight vehicle-kilometres in 2020 were run by empty vehicles: 24 per cent in national transport and 13 per cent in international transport.
Dead volume collects in four places: the wall and insulation of the box, the gaps between boxes that ignore the module, the space left at the top when box height and vehicle height do not divide into whole layers, and the return leg when an emptied box still takes the space of a full one. Insulation thickness is not counted as a loss, it is what holds the temperature.
| Ratio | Calculation | What it shows |
|---|---|---|
| Vehicle utilisation | external volume of boxes / vehicle interior volume | stowage efficiency |
| Box efficiency | product volume / external volume of boxes | share taken by walls and inner gaps |
A hypothetical example: in a box that measures 600 x 400 x 300 mm outside (0.072 m³) and 520 x 320 x 220 mm inside (0.037 m³), product can fill at most about half of the outer volume.
ISO 3394 builds the dimensions of rigid rectangular packages on modules of 600 x 400, 600 x 500 and 550 x 366 mm, and ISO 3676 defines the pallet plan dimensions; a 600 x 400 mm box fits a 1200 x 800 mm pallet exactly, four to a layer.
Record loaded and empty returns separately and measure the folded or nested size of collapsible boxes as well; compare periods with the same vehicle, product mix and stowage rule.
