It is also possible to travel by train, but unlike in Europe it is not a very popular choice of transportation and it is not yet that massive.
In Santiago de Chile, the two most important routes in terms of train service are the Terrasur and the Trens Metropolitanos.
Terrasur, connects Santiago with Chillan (southern Chile) and makes several stops on the way. Its price depends on the requested destination. Its cabins are modern, fast and have a business class feature.
Trenes Metropolitanos, unlike Terrasur, covers shorter routes, connecting the city of Santiago with various districts around the capital. It has 18 stations, among them: Rancagua, Paine, Buin y Linares and many more.
For more information about the rail transportation in Santiago you can visit Wikipedia.