Infrastructure main goal is to gain economy and gain strategic edge over others.

I suggest infrastructure can be as follow:

Viaduct: This can be build on impassable or passable valley and can be of 1 or 2 tiles. This can be build specialy only build for road and automatically build for railway if required. 

Tunnel: This is similar to viaduct and can be 3 tile long and automatically build for railway if required and build specially for road.

Railway: This infrastructure will cause high increase in production, gold and bring population from far away city like 20-30 tiles. It effect increase when more cities are added to network even outpost can also be added. It can help in more efficient way to move military units. It benefit increase if connected to another civ.

Population i am saying means people not change city but the population which is ideal can contribute to nearby city which have vacant post.

High speed rail: It will help to get population from more faraway city like 50-60 tile and increase income. It unlock at modern era.

Expressway: It will increase production, gold income and population but less than railway and population range can be 20-30 tiles. Viaduct and tunnel will construct automatically.

The expressway would construct on existing road network when we construct it cause shortcut by making viaduct and tunnel.

+1
+a new transport district with visual buildings to build: 
- The main railway station (opens the possibility of building a railway connection)
- Bus Hub (increases city happiness by providing public transport in the city)
- Logistic Railway Center (transport of goods in containers by rail,trade routes can use the railroad)

Dude, you created the same thread few days ago in the design section. Why create another one? 

AquilaSPQR wrote:

Dude, you created the same thread few days ago in the design section. Why create another one? 

There people are not active.