At our club meets we usually have a couple of areas containing garden centre soil, gravel, etc...the guys with the loaders, shovels, JCB's, etc are always in these areas ready to load the tipper trucks. A tipper goes in one end, gets loaded, goes off to the other end of the circuit and tips the load...another tipper gets loaded and fetches it back again.
It provides Joe Public with something to watch, gives the machine operators a chance to play with their often very expensive machines, and gives the tipper drivers a chance to show off their trucks.