A track worker killed by a passenger train in south London was on a zero-hours contract, probably fatigued, and left exposed to danger when a colleague failed to turn up for work, investigators have found.

Safety inspectors called for an overhaul of “Victorian methods of protection”, and demanded Network Rail review how its outsourced labour suppliers ensure people are fit to work. They said previous calls for reform, after a death in 2007 and a near-miss in 2017, had not been heeded.

The report comes a week after the deaths of two other track workers, who were hit by a train in south Wales.

The Rail Accident Investigation Branch’s report into the incident at Stoats Nest Junction, near Purley, last autumn said the unnamed man, aged 37, from Upminster in east London, had been placing equipment on the track to protect the line for overnight engineering works.

He was hit by a Southern train from London Victoria to Three Bridges at 12.28am on 6 November. He was walking with his back to the train, which was travelling at about 69 mph, on an unprotected stretch of track.

The RAIB said the worker was probably fatigued and may have been distracted by personal issues. A second person who should have been with him had not turned up for work that night.

The labour supplier had “not sufficiently identified and addressed the risk of fatigue among zero-hours contracted staff”, nor “identified or prevented staff absenting themselves from work without being detected”, the report said.

Simon French, the chief inspector of rail accidents, said the nature of the contracts had “significant” safety risks. He said: “When workers are employed on a casual basis on zero-hours contracts, there can be great pressure for them to try and juggle multiple jobs to make ends meet.

“The possible effects of such patterns of employment on fatigue and fitness for work are significant. We are therefore recommending that the railway industry reviews the way it manages the use of staff on zero-hours contracts.”

French said modern technology meant there were many ways of improving safety: “The continuing requirement for people to go on to the track to place and remove red lamps and explosive detonators, as part of the arrangements for protecting engineering work on the railway, is something that RAIB has queried before.

“The industry should continue to explore ways of eliminating the need for Victorian methods of protection on the 21st-century railway. It is deeply saddening that another person has died while putting down protection for his fellow railway workers. There must be a better way.”

The risks were highlighted last week by the deaths of two other workers, Gareth Delbridge and Michael Lewis, who were hit by a Great Western train near Port Talbot. The incident is the subject of a British Transport Police and RAIB investigation.

The Purley incident could lead to huge fines for Network Rail, with the rail regulator examining possible health and safety breaches. A spokesman from the Office of Rail and Road confirmed it was investigating.

On Tuesday Network Rail announced the launch of a safety task force with £70m funding to improve track worker safety.

Sam Chessex, the acting route managing director of Network Rail’s south-east route, said the incident was “a terrible tragedy involving a member of the railway family”.

She said: “Network Rail does not use zero-hour contracts, and our code of conduct sets out what we expect from suppliers who do use them to ensure contractor safety. As a result of this incident we are reviewing our standards and our supplier practices to ensure they are focused on contractor safety.”