It really depends on the specifics of the top track. Are people added to the top track just in time to be run over by the trolley, or is the track pre-populated with an endless arrangement of people waiting to be run over.

If it's the later case, how do people further down the track survive for an unbounded amount of time while waiting to be run over? Do they wait, bound and screaming for an eternity? How do they survive long enough to be alive before being run over?

I need to know if the top track reduces to running over an infinite arrangement of corpses. Or, if trolley time for the top track has some different meaning, such that the trolley brings an end to the finite life lived by each next person on the track.