I made a similar post a few days ago before I saw this.
Similar to cargo with a bit of a twist. The train would be a fairly common event with different variations. The railroad would hit several key locations such as trainyard, harbor, military tunnels, etc. The train would be going fast enough for horses and cars to catch it but would slow down when passing near monuments enough for people on foot to get on.
1st variation- most common
Remember that naked barge that was fairly close to making it in the game. This variation could severe a similar purpose. This train would be controlled by the NPC bandit group and would be guarded by them. The train would act as a mobile safe zone with limited time items for sale.
2nd variation- uncommon
The cargo train would be similar to a high tier monument. Guarded by hostile scientists and juggernauts. The train would be stocked with higher tier loot and even a chinook crate.
3rd variation- rare
The armored train, similar to taking a boss vehicle like Bradley or helicopter. The train could be defended by a multitude of defenses but always has some form if auto cannon defending it. It may also have SAM turrets or gunslits for scientists inside the train to shoot out. To get the loot of the armored train vital modules of the train must be destroyed for the train to stop and drop loot. These modules may include the auto cannon cart, the engine cart, or even the conductors cart. After these vital modules are destroyed then flaming loot boxes will drop like helicopter and Bradley.
Each train variation should have chances for different modules to spawn, for example the bandit train might spawn with a small helipad one time and without one a different time. Same could go for the other two variations. This would change each train event and the tactics needed to use them.
Also if you’re adding trains you kinda have to add a craftable handcrank cart.