Transport NSW has hit back at suggestions a piece of obsolete equipment hobbled Sydney's train network, causing commuter chaos during the afternoon peak.
While a confidential report uncovered by the Sydney Morning Herald warned trains' digital radio system components were obsolete, officials identified the culprit as an unrelated router.
The city rail network's digital radio system, which controls communication between trains and the rail operations centre, failed at 2.45pm last Wednesday, stranding thousands of passengers for over an hour and causing major delays.
Sydney Trains said it determined in 2021 that parts of the Digital Train Radio System (DTRS) would become "obsolete" in the next five years.
Plans were being made for a broader technology upgrade based on the 5G spectrum, while relying on the old system until the changes could be made.
But in a statement addressing media reports about the obsolescence risk on Tuesday, Transport NSW claimed it applied only to wireless base station components, which did not cause the shutdown.
The faulty component was a router that is readily available on the market and not obsolete.
"The current DTRS has been operating across the rail network in Sydney since 2016 and regular upgrades, including one in March 2023, are a regular part of the ongoing maintenance program, with component spares also held in stock," the statement read.
"DTRS technology is used widely in railway systems around the world."
Despite battling ongoing industrial action, adverse weather events and the impact of COVID-19, Sydney Trains says it has prioritised an extensive maintenance program across the network.
Around $1.4 billion is slated to be spent conducting maintenance this financial year, with $800 million already spent.
Labor's transport spokeswoman Jo Haylen said Sydney Trains most recent maintenance backlog for the 2021-22 year was $670 million.
"Passengers simply want a safe and reliable public transport system," she said.
Premier Dominic Perrottet called the outage a "freak incident".
"These incidents happen from time to time, they do," he said.
"Transport did everything they could to get it back on and up and running as soon as they could - and they did in a little over an hour."
The breakdown stranded 250,000 commuters trying to get home, causing a ripple effect across the city as buses quickly filled up and chaos ensued.
Every Sydney train was parked for 90 minutes, awaiting instructions before getting the all-clear just after 4pm.
Train drivers are reportedly going to get analogue hand-held radios as a backup in case communications are temporarily severed again.
A Sydney trains spokeswoman said analogue radio is an approved alternate communication platform within the organisation's network rules.
"It is not uncommon for analogue radio to be used as an additional backup option," she said.
