A vehicle travelling along a straight path which extends to the horizon uninterrupted remains in state of indeterminacy-- existing invisibly at all points along the road simultaneously-- until its waveform is collapsed by a villain entering the road. This causes the vehicle to coalesce into an observable form at that location, maintaining high velocity. Classical cartoon physics take over at this point.
RDB translation into plain English: As soon as Wile E. Coyote steps into the road, the bus appears to run him down.
From an autobiography of Chuck Young, creator of the Road Runner cartoons ("Chuck Amuck: The Life And Times Of An Animated Cartoonist", and "That's All Folks: The Art Of Warner Bros. Animation". Copyrights and trademarks C. Jones et Warner Bros)