Premetro

Here infrastructure is gradually built with the goal to use rapid transit trains in the distant future, but using trams or light rail vehicles preliminary in the meantime.

The large scale report "Light Rail Transit: A State of the Art Review" describes on page 9 the relationship of premetro systems to broader terms as follows: The same distinction is made in glossaries.

This tunnel was intended solely to reduce streetcar congestion on surface streets, not for later conversion to metro service.

However, the small loading gauge, tight curves, and steep grades of the streetcar tunnels required shorter metro cars than otherwise desirable.

[11] The modern premetro concept Stadtbahn began in 1960s Germany, as rising traffic congestion due to auto ownership led to the construction of new transit systems.