Rail is a grounded, guided, low grip transport system

It needs specific ground infrastructure which is costly to implement and maintain but contributes greatly to efficient land use.
The rails provide the guiding system. By controlling the direction of the train, they allow it to go very fast. However, this means that trains cannot overtake one another.

Low grip refers to the contact of a steel wheel on a steel rail. As the train glides on the track, it is easy to carry very heavy loads with a low environmental footprint, but very difficult to brake and stop, or to accommodate steep gradients.
Because of the huge investment required, rail can only be commercially attractive and financially acceptable as a mass transport system. This is just as well, as it is typically a heavy haul system.

Classical rail

Classical rail networks are largely spread worldwide. They comply with various gauge standards, but the best performance is achieved using the 1.435 m track width.
Most of these networks are made up of mixed-traffic tracks. The maximum speed never exceeds 200 km/h (exceptionally 220 km/h). Built during the 19th century, many stations are now located in the centres of large cities where most urban transport lines converge, facilitating door-to-door trips.

When compared to other transport modes, classical rail has proven to be very safe and environmentally efficient. However, the aviation and automotive sectors have introduced many improvements and are still introducing innovations in their respective systems. This has had a strong negative impact on rail market shares for medium- and long-distance trips.

More than 50 years ago, Japan, followed by France and many other countries, decided to stop the decline of classical rail in this market segment by introducing brand new concepts for the rail mode rather than upgrading existing structures. This represented the birth of high speed rail.