Nice idea. Also it can impart probability when a city merges adjacent regions. Railway was the key technology of city expansion started during the industrial revolution. 

I suggest new idea for humankind the railway will provide supplies which will increase power of units and also capable of bringing reinforcement of unit from distant tile.

How do we know it is not already included?  Also, would railways be similar to roads in Civ 6? so they would only be beneficial for trade and units moving more quickly over tiles? ?

If you see humankind we have limited army generals hence limited army. So we should be sure about deployment of troops to protect border.

Railway can increase deployment and increase food sharing and trade.

I proposed that it will not replace roads but we will have choice for train track and with tracks there will be tunnel formation and bridges between canyon.

There could be a collective technologi ( ISO) which allows to connect to railway systems of other nations.

 It could also upgrade tourisms and increase influence.

The technologi Maglev could improve its efficiency .

I like the idea of underground lanes and the idea of building each part above ground (cheaper and easier to maintain) or beneath ground (  more expensive, but can cross mountains, rivers and even ocean ( but that should be costly and require a own technologie, otherwise it would be to over powerd)).

I agree with you that technology give more ways to approach the area.

Roads! Roads! Roads! & infrastructure

I truly hope that railroads will not only grant bonus movement on the map, but also have powerful economic and civil effects. Transport of goods and people by rail truly revolutionized the world, and there are so many gameplay bonuses that could be tied to it. A few examples off the top of my head:

- Bonus food and production for cities connected by rail

- More efficient trade routes

- Ability to develop outposts and new colonies faster by supplying goods more quickly

- Population migration events/projects

- Faster culture spread to cities connected by rail

And following this, air transport and travel should also have huge impacts when it is unlocked. 

To the previously described version of the mechanics of railway stations/freight stations, you can add river stations in the same way. Which give some bonuses for cities connected by rivers, if there are river stations\river ports.

Another point could be the option to choose which kind of train the player uses where whitch could influence the look and/ or game mechanics.

Zugg_zug wrote:

I truly hope that railroads will not only grant bonus movement on the map, but also have powerful economic and civil effects. Transport of goods and people by rail truly revolutionized the world, and there are so many gameplay bonuses that could be tied to it. A few examples off the top of my head:

- Bonus food and production for cities connected by rail

- More efficient trade routes

- Ability to develop outposts and new colonies faster by supplying goods more quickly

- Population migration events/projects

- Faster culture spread to cities connected by rail

And following this, air transport and travel should also have huge impacts when it is unlocked.

You are so right. Too bad that micromanagement of roads to railroads conversion is likely to be a very tedious endevour. Just like it was in CIV 4 

It can also help in reinforcement from distance.