The literature is full of interesting applications requiring capacity planning in transportation networks. A quick search revealed hundreds of results. A few interesting application areas below (there are dozens).
Theme Parks:
Ahmadi, R.H. 1997. Managing Capacity and Flow at Theme Parks, Operations Research, Vol 45, No 1, 1–13, https://www.jstor.org/stable/171921.
Dial-a-Ride Problems:
Tellez, O., Vercraene, S., Lehuede, F., Peton, O., and Monteiro, T. 2018. The fleet size and mix dial-a-ride problem with reconfigurable vehicle capacity, Transportation Research Part C: Emerging Technologies, Vol 91, 99-123, https://doi.org/10.1016/j.trc.2018.03.020.
Military Applications:
Longhorn, D.C. and Muckensturm, J.R. 2019. Determining nodal capacities for military distribution problems, Journal of Defense Analytics and Logistics, Vol 3 No 2, 110-130, https://doi.org/10.1108/JDAL-03-2019-0006.
Longhorn, D.C. and Stobbs, J.D. 2021. A heuristic approach applied to the fleet sizing problem for military ground vehicles, Journal of Defense Analytics and Logistics, Vol 5, No 1, 2-20, https://doi.org/10.1108/JDAL-03-2020-0005.
Disclosure: I am NOT one of the authors.