I am working on a project related to an emergency evacuation:
Find the minimum time to make $n$ people to evacuate the city (travel time of the slowest). There is 1 vehicle that can contain $p$ people and travel at the speed of the slowest person of the group. One person has to bring back the vehicle used for transportation.
This problem is a generalization to the bridge crossing / torch problem.
I found solution for $p \leq 2$ which comes down to sort the people by travel time and to iterate pairwise whether it is better for the pair of people to travel together using 2 runners or to travel separately using 1 runner.
I tried to adapt it for $p=3$ but things escalated quickly and I ended up with many strategies to compare for every group of 3 persons with 1, 2, 3 runners and could not find a way to generalize for $p \geq 3$.