What is "palangal"

Palangal is a 1981 Malayalam film written by John Paul Puthusery and directed by Bharathan starring Nedumudi Venu, Zarina Wahab, Bharath Gopi and Shankar. Film's plot is a love story of a man who works in railway lines and a woman who lost his lover in railway lines. Majority of the film was shot in Shornur due to the persistence of Bharathan as he always wants to hear the siren of the trains in the whole film. Coal engine was used in those periods in train and engines were brought from Madras for shooting this film.