Sydney rail workers are "shattered" after a Sydney Trains employee was struck and killed by a train on Saturday.

Charles Lagaaia was working on the T1 Western Line at Clyde when he was struck by a train just after 6am.

The state government has its own transport agenda Credit:Fiona Morris

Authorities are investigating how Mr Lagaaia, a signal mechanic, was killed by a Blue Mountains service in the course of completing "important maintenance work".

Rail, Train and Bus union national secretary Bob Nanva said workers were "shattered" after the accident.