Methods and systems for reverse-iterating a backward planner determining trajectories for vehicles of a fleet of vehicles are provided. In one example an iterator configured for recursively determining the contingency tables at successive time steps in a computational iteration order from a target time to an initial time is caused to reverse-generate the contingency tables in an order from the initial time to the target time. Reverse-generation is caused by recursively: (i) subdividing a sequence of time steps by a factor of at least two into successively smaller sub-sequences, (ii) iterating in a computational iteration order over each recursively subdivided sub-sequence, and (iii) generating a contingency table closest in time to the initial time for the recursive iteration over each recursively subdivided sub-sequence.