The tunnels
The tunnels are passages for trains under mountains, hills and rivers. The tunnels are dark but the trains are well lighted. Electric motors are often used, this avoids the smoke of steam engines which is very unpleasant in the tunnels.
The water tank
The water tank is seen frequently along the route of the railroads and plenty of water must be taken on and carried in the engine tender to make steam which is the power used to drive the big engines.