The term's previous use in railway track terminology (e.g., India's Grand Trunk Road, Canada's Grand Trunk Railway), which came from the natural models mentioned above, was the other obvious influence.
Unfortunately, due to some short sightedness, no provision had been made for deep wading trunking and the A30 was unable to participate in the Normandy landings; the tank had to wait until ports had been secured and the Mulberry harbours completed.