The driver of a train that ploughed into a safety barrier at Richmond station in Sydney's north-west "felt dark, dizzy and powerless" just moments before the crash injuring 16 people.

Safety investigators believe it was possible the train driver experienced a blackout or a micro-sleep. However, they are unable to determine conclusively the cause of the crash on January 22 last year because of the lack of closed-circuit TV inside the driver's cab.

The crash has highlighted Sydney Trains' operational shortcomings to ensure enough "multi-layered defences" existed to stop trains from over speeding.

The train smashed into the safety barrier at Richmond station in January last year. Credit:Christopher Pearce

A final report into the crash by the Australian Transport Safety Bureau found several factors increased the safety risk, including deficiencies in the buffer stop design at Richmond and inconsistencies in Sydney Trains' rostering of the driver before the crash.