The height of the container while on the truck is 4.2m. You need to allow at least this height when going under powerlines/trees, eves of houses/factories or through doorways.
Even though the container is 2.44m wide, the truck & mirrors etc. needs an opening of at least 2.9m.
When the tray lifts up, the top front of the container will go up to 6.5m in height while unloading. This needs to be considered when unloading near/under powerlines and trees or inside factories.
The truck will need clear space in front of the container to drive out from under the container & then manoeuvring space to drive away. This needs to be at least 12 metres for a 20’ container on a rigid truck or 18 metres for a 40’ container on a semitrailer.
The land where the truck parks to unload needs to be relatively level. If the site slopes, the truck can unload if parked facing up or down the slope. If the truck is positioned facing across the slope, as the tray lifts up and the truck starts to drive out from under the container it can jump the side rail of the tray and roll over.
Most transport companies don’t like to take their vehicles off road. If delivery is into an area where the ground isn’t sealed or compacted / hardstand, the driver will inspect the area and make a judgement whether or not to proceed. If the vehicle becomes bogged / stuck you will be liable for the recovery cost. So it’s a good idea to make sure you identify any soft or wet areas, old rubble drains, recently excavated / filled areas etc. then advise the driver of their location. Also have an alternate site to place the container in case the driver won’t go off the compacted surface.