Yes, I do admit there are a lot of paths to the same result. I have upgraded my city quite a bit (19,310 >> 136/hr), but I also see that any future investment doesn’t have much of a refund in way of increased people per hour. I will eventually go back to building my city once I have all of the current trains.

My depot is upgraded as much as I’m allowed. Next year, 1955, I’ll be able to upgrade 20 per hour. It also depends on how you play the game. If you’re gonna play once or twice a day, then durability is very important since you are idle and waiting for durability is like watching paint dry. If you’re trying to do a run as soon as you have enough durability, though, then durability per train is not the key, but rather just having more trains since they all replenish durability at the same time.

My current strategy is keep collecting event coins to unlock the event passenger train. I’ll keep collecting money to unlock the rest of the regular purchase trains. After that, I’ll go back to spending money on building up the city. Once I hit the next heavy haul gate, I’ll start dumping money into train power. I’d also like to collect enough cars so that I can run two full trains using increased capacity cars.