A high-voltage wire which fell onto a train in Sydney earlier this year, trapping 300 passengers and causing massive commuter disruption, was identified as a risk as early as 2020, a rail safety review has found.

The Minns government on Tuesday released the findings of the “sobering” report, which was commissioned following the Homebush incident in May. The study identified the need for extra care of critical assets on the city’s ageing heavy rail network.

The review found the response to the incident, including a three-hour operation to detrain trapped passengers, was too slow. Communication by Sydney Trains was inadequate, the report said, which contributed to widespread delays rolling into a second day.

The report said there was a “lack of care” offered to the trapped passengers.

“No attempt to take their details or follow up, if requested, was made. The toilet facilities at the station were opened, but water was only provided if asked for.”

The NSW transport minister, John Graham, said the report showed the city’s rail system was “not up to scratch”.

“The missteps and mishandling of the response ensured two days of chaos on our city’s public transport system when a well-managed response could – and should – have limited disruption to one day,” he said.

The government has committed to implementing all 12 of the report’s recommendations, including an overhaul of maintenance systems, with an investment of $458.4m over four years.

The review – led by transport industry expert Kerry Schott – found a 630mm section of the wire was first identified as being below its operational capacity or “condemning limit” of 10.9mm during an outsourced network-wide inspection in 2020.

This inspection was outside the normal maintenance program, and the wire was not repaired, although it was visually inspected as recently as April this year.

The review found that visual inspectors relied on binoculars.

“An overhead wire that carries power to the train broke and fell onto the roof of the incident train. We found that despite visual inspections of this wire every 13 weeks, and planned physical measurement every four years, the fact that it was thin and beyond breaking limits was not detected,” the report stated.

“The visual inspectors rely on binoculars and cannot get close enough for an adequate view. In our view, their tools are insufficient for the job they are given. The reason why the physical measurements missed the issue appears to be that this section of wiring was not measured. Added to these failings was a trial of technology done in 2020 that did detect the issue … was not followed up.”

Schott told reporters on Tuesday: “While looking at wires through binoculars does on the face of it sound weird, the difficulty with it is that we do need to keep the trains running.”

Sydney Trains has committed to replacing binoculars with hand-held laser devices by December.

Graham told reporters on Tuesday that a network-wide digital scan following the incident had identified 126 additional “points of interest” which have since been resolved.

The Sydney Trains chief executive, Matt Longland, said the network had “let passengers down”.

“I do apologise for what they had to experience over those two days,” he said.

“It should have been picked up in the inspection process, and it could have been avoided. Secondly, the response and the repair took far too long.”

The review identified significant issues with the response by the body that runs the city’s trains – the Rail Operations Centre (Roc). Delays into a second day appeared to have been caused by a “lack of management capability in dealing with an incident of this kind”, Schott’s report concluded.

Asked if anyone has been dismissed from Roc following the incident, Longland said there had been a “handful of changes”.

“I have made a number of changes to the leadership, both in engineering and also in operations, and people have left the organisation … I don’t want to go into the detail of individual circumstances.”

Schott said it was likely there had been knock-on effects on maintenance from a protracted industrial dispute between the government and unions, including the Rail, Tram and Bus Union (RTBU), which was resolved just days before the incident.

“It was such a contracted dispute as well, that it does mean that relations between the unionised staff and management were probably still a bit tricky,” she said on Thursday.

Further disruption looms for the city’s commuters, with union members on the city’s metro line, unaffected by the May incident, set to vote on taking industrial action this month. The RTBU was contacted for comment.