I’m not against planes, I just don’t see the point of bothering to implement them. If they were implemented correctly, they’d be a perpetual loss-maker, as they only make the remotest sense transporting over international/intercontinental distances. Domestic flights between neighbouring towns never exactly turned into any kind of industry in the real world.
Ships/boats are a mixed bag. Earlier in the game, canals and cargo barges would actually make some sense, as that has some precident in reality… but also in reality, the collapse of that particular industry was caused by the rise of trains and motor-vehicles, so it would at best add some early flavour to the game in a similar way that the horse-and-cart does currently.
Modern-day commuter-boats like the Thames Clipper make decent sense for Train Fever. They’re still dwarfed by train and car travel, but at least it would be relevant on the scale the game deals with. I’d gladly see those added, as I think it would add some nice extra character to the game.
Large scale container shipping suffers the same issues as air travel… it only really makes sense on an international/intercontinental scale, where the relatively low speed is offset by the sheer vastness of the capacity. It’s a scale of economy that wouldn’t make any sense inside the scope of a Train Fever map.
The idea of having airports and shipping ports as game-generated industries seems a much better idea to me. In the early 1900’s, you could start out with a bunch of scattered small airfields, and the ones you feed with services could gradually expand in a similar way to towns, until they turn into major international hubs. In modern times, one or two major ports would require massive capacity passenger and cargo services to connect them to up to cities, and could be considered vital growth motivators. The late game could end up with a significant focus on providing efficient international links. It would also be rather neat to have maps with a section of coastline, along with some river estuaries/natural harbours/cliffs, etc. Weaving train lines around the coast of a hilly map like Brunel did in South West England could be rather satisfying 🙂