An urgent maintenance blitz is needed to fix Sydney’s growing backlog of failing rail infrastructure as the government works to reverse the trend of late and cancelled trains.

A surge in infrastructure-related defects, coupled with a growing backlog of compliance checks on those defects, were the main causes of disruption across the rail network, an interim review of Sydney Trains released on Monday has found.

The record backlog of infrastructure defects of between 35,000 and 40,000 was a concern, said National Transport Commission chair Carolyn Walsh, who heads the review.

“We believe that is not going to just bounce back under business-as-usual arrangements,” Ms Walsh said on Monday

“We’re actually recommending that the backlog of maintenance must be immediately and urgently addressed in order to get the resilience of the network back and to ensure its ongoing safety.”

All 12 recommendations in the interim report would be supported by the government, Transport Minister Jo Haylen said.

Staff had been instructed to begin work on speeding up checks as soon as possible.

There are 1265 priority one defects that must be checked every seven days and another large number of priority two defects need an inspection every 28 days, in case a breakage occurs.

The city circle and inner west lines have the worst backlog and were suffering the most severe reliability issues, Sydney Trains chief executive Matthew Longland said.

“As we’re building the plan, we’re looking at the number of incidents and how they flow through to the reliability of services and that’s how we’ll prioritise the work that we do first,” he said on Monday.

An “ambient level” of defects was expected across the network at any time but the backlog has blown out to unsustainable levels.

The review into problems across the NSW rail network was announced days after Labor won the March 25 election.

March was a particularly bad month for rail reliability when a radio system outage crashed the Sydney network, a live wire landed on a train at Panania trapping 500 people for 90 minutes and signal outages caused delays on election day.

That followed 12 months of delays, disruptions and widespread outages as the rail unions battled with the coalition government.

IThe Sydney Trains timetable could also be overhauled next year, as the panel flagged ongoing issues.

The timetable, designed to boost passenger numbers as the network became overcrowded, has stretched the capacity of Sydney Trains staff, leaving services fragile since its introduction.

The review found response times and the flow of information to commuters could improve by reviewing the chain of command at Sydney Trains and Transport for NSW.

A final report will be handed down in October.

– AAP