A former Sydney Trains employee who saw his colleague fatally hit by a train is fighting to get his job back after he was blamed over the accident and sacked.

Adam, who requested his surname be withheld, has lived with severe PTSD since he saw his colleague Charles Lagaaia get hit and killed by a train during maintenance work in Sydney's west in June 2016.

Adam, who was sacked by Sydney Trains, has lived with PTSD since 2016. Credit:Wolter Peeters

The signal electrician, who had worked for Sydney Trains for 13 years, was asked to help with overnight work to replace wooden sleepers at Clyde so an extra train service could be stabled there ahead of a race day at Rosehill.

At 6.08am on June 18, Adam and Mr Lagaaia were removing a clip from part of the track, which they both believed to be out of operation, when a train suddenly approached. Mr Lagaaia was unable to move out of the way and was killed.