Is train common noun or proper noun?

The Word 'train' is both a verb and a noun.

The noun train is a common noun, a general Word for a connected line of railroad cars; a general Word for a part of a gown that trails behind the wearer; a general Word for a connected series of events, actions, or ideas; a general Word for a series of moving machine parts for transmitting motion.

A proper noun is the name of a person, place, thing, or a title; for example:

The Essex Steam Train (attraction), Essex, MA

Train Ave, Cleveland, OH

"The Train", 1964 movie starring Burt Lancaster