Locomotive's

I love the idea! Right now I am mining coal on the back end of my island, and those huge haul trucks are burning a LOT of precious diesel to get it to the power plant. FYI I would gladly buy trains as a DLC- devs need to eat too! :-)
Balance would be requiring lots of resources to build the railroad, but costing fewer resources per unit/distance to move products.
Suggestions:
Railroad tracks- Tier 1 requires wood & iron- low speed limit. T2 wood and steel- higher speed limit. T3 rconcrete, steel & a tiny amount of rubber- highest speed limit.
Locomotives- T1 requires iron & mechaincal parts, uses coal & sand- hauls few wagons. T2 steel & mechanical parts, use coal & sand- more wagons. T3 steel & vehicle parts, use diesel & sand- even more wagons. Possible T4, steel & electronics, uses sand, consumes electricity.
Would need a vehicle depot to supply the trains with fuel & sand- also stations for loading and unloading products, with connections in and out to storages.

I do not think that trains are needed in COI. I would prefer to have "internal" cargo barges or ships. this way you can move stuff from one end of the map to the other much more neatly that adding train tracks on a map that is already difficult enough to make everything fit with conveyors and pipes.

If you leave idea of "island" and have maps without sea or only partially-sea, you can make trains to work just like cargo ships! You can build and upgrade stations on edge of maps and then CAN watch trains to get loaded and unloaded and drive around the tracks (make it looking complex enough, more track in stations etc.) and it would not change gameplay. Win-win option?

Many keep knocking the scale of the island and trains but try to think of a minecart rather than large locomotives transporting many cars of freight and cargo around the map. A simple point A to B straight line would help expedite ore removal/crops/water/wastewater transport over a distance.

I do love to see a train like or maybe road train? To transfer resources among different production area

Not sure about trains specifically, but I do think something is very much needed to facilitate bulk transfer of mixed cargo from one side of an island to another, particularly on the larger islands or where passing through the middle is impractical until very late game. I and not sure trains is the answer, but maybe a significant improvement to transport logistics specifically aimed at bundling a mixed bus from one zone to another.
Think maybe transport hub building at each end that packs stuff (from belts/pipes) into shipping containers (each contains completely mixed cargo) truck move the containers, and they are unpacked at the destination hub back onto belts/pipes etc. Truck can then be assigned to the inter-hub routes as currently.
Each hub might have say 10 each of pipe, u and flat conveyor ports in and out, or maybe one with in ports and another with out ports etc. In fact the hubs could be done like the existing cargo ship ports with their cargo type modules. Max of 12/16?

Too right, trains are a huge part of our industry. Yet maybe bigger islands too?

simple Mine Cars would do the job and take away the some of the need for such high road transport

you dont need trains in this game, you have belts to do the job lol. takes to much space and is really not needed, i just put a big stirage close to a mine and connect it with belts where it needs to be , is much better then trains, this is not anno right!

Instead of trains running on rails - Land trains - basically a truck with several trailers - and specific load and drop points would be more practical?

I think trains call for bigger islands with longer distances. But maybe I'm wrong.

The more content the better and plus I love trains so please add them.
You could have trains transport large amounts of resources to replace having long pipes/conveyors on the map.
We mainly just need cargo trains as passengers trains would be pointless as the game doesn’t have people models.

It would be good for underground mines it takes many people and a mining train but it could get more ressurces out of the ground like this mining train that got out of a mine

Schaffe platz für eine Halde und beute die Lagerstätten komplett aus. Abraum der nächsten Lagerstätte ins Loch gekippt ...fertig!

smol trains and greater trains. yes its good.

Trains
General Track - T2 Construction OR Iron/Wood
Track Crossings - T2 Const + Concrete
Engine - T1 powered by coal
Wagons - T1-180 T2-360 T3-720 T4-1080
Each Engine and Wagon take up a vehicle slot.
Can go up a smooth gradient hill but slows down extensively.
Storage can be lined up with train stop, transfer storage>Wagon can be faster than belt.
Depending on how you line up the train stop, different stops can load/unload different wagons.
Scenarios:
Island loop - Train loads up at each mine and unloads at a centralized smelter.
Inner Island Transfer - Train loads up at the the assembly area and unloads at the Contracted Cargo Ship.
Long Distance Transport - From a mine at the opposite end of the island back to the main area. (Curland Gold!)
Developement considerations:
Setting a train(vehicle) to follow a track.
A way to stop and 'pause' a vehicle temporarily while a train crossing is blocked.
Wagons would essentially be a moving storage container

How I see trains working is you'd have 3 tiers, T1 Coal, T2 Diesel, T3 Electric. Each increment having more speed at the cost of a higher tier of mainatance and building costs.
These trains wouldn't use truck spots but train engine limits. Let's say start with 2 and up to 10 depending on research.
You would build them by placing a land version of the Cargo Dock which we'll call it the Train Depot; This would put the engine down, next you attach storage modules to it in the standard 2x, 4x, ect way the type you place down would determining what wagon cars are added to the train. Fuel for the train would be fed into the depot same as the Cargo Dock.
Using this system If each wagon held as much as a T3 truck, You could free up the equivalent of 8 T3 trucks going between 2 points, potentially multiplied if the train moved faster then the trucks. This would be a huge boon regardless of how big or small a island is.

You don't really need a bigger map for trains. The first island is pretty huge, and trains could just run back and forth like conveyor belts. Even if it was a 4 car train with engine, making stops between engine houses. To drop off resources or linked to the assembly, storage units. Or they could just have modified the storage for trains only. "I'm not sure," it would be much different from conveyor belt. The distant between copper, iron mines is huge way from your industrial park. Trust me I spend a lot of time moving them around, with copy and paste. I could've avoided that with a locomotive. I do like Captain of Industry and all it has to offer, It was just a suggestion I had on steam recently. I play games like Factorio and Satisfactory, I wind my trains around the map, so I don't have to use conveyor belts. Just looks cleaner if you ask me. So, I support the idea!
Would I pay? Sure would

With the new update and the map editor, really you can go large distances with a train, would be awesome.

For those who haven't seen it.
CD #43: Loans, Difficulties, Surfaces
https://www.captain-of-industry.com/post/cd-43
"Besides working on the large map editor, we were building infrastructure supporting a few features, such as roads and trains."