Carryfast:
Assuming the type of runaway described by Juddian what are those yellow things stowed on the front bulkhead ?.
Those plastic chocks are about as much use a chocolate teapot, more often than not they’ll bounce down the road in front of the wheel until such time as the vehicle has enough momentum, by which time IF the chock eventually digs in the wheel goes straight over (or through when loaded) it often smashing it to pieces…still they look the part 
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