The NSW premier has blamed ongoing chaos on the rail network on the unions after the transport minister assured the parliament future communications between management and government will be more precise.
Dominic Perrottet told parliament on Wednesday the "entire situation could have been avoided but for the actions of the unions on Sunday".
The premier, who was not told about the shutdown in advance, said he had since received advice from Sydney Trains there was a "substantial safety concern" over protected industrial action planned by the union.
"(Unions) have not even hidden at any point in time during this entire process their view ... is to cause massive chaos and industrial issues across New South Wales."
It comes after Transport Minister David Elliott faced questions over who in the department made the decision to shut the network early on Monday, which affected up to a million commuters.
He conceded communication between the department and his office had not been "sufficiently precise" when the decision was made.
Those senior transport bureaucrats were told in a meeting today any major decisions need to be subject to "written briefing and written endorsement", Mr Elliott said.
"That will ensure there are no further incidents of this nature in the future.
"Whatever process shortcoming occurred on Sunday night, the ultimate outcome would not have changed."
The comments came after the premier said he was seeking advice on whether the law was broken by those bureaucrats making those decisions without contacting the minister.
Mr Perrottet said he "should have been told" about the decision and is looking into whether proper procedures were followed, News Corp reported.
"That needs to be interpreted and I'm seeking advice," he said.
He has since ordered his ministers to be available 24 hours a day after the shutdown was blamed on the transport minister being asleep.
Mr Elliott said on Tuesday that if he was contacted by bureaucrats in the early hours of Monday, he probably would not have answered because he was asleep.
"The minister will reflect on that and realise that all ministers are available 24/7," Mr Perrottet said on Wednesday.
"My expectation is that ministers are immensely connected to the operational matters that are occurring within their portfolios."
NSW Opposition Leader Chris Minns said Mr Elliott had not given satisfactory details as to what he knew, and when he knew it, before the rail network shutdown.
"What's the point of having a government if the minister responsible is not even told, or does not know, what's happening on his watch?" Mr Minns asked.
Labor's transport spokeswoman Jo Haylen said it was "absolutely implausible that a public servant alone would shut down Sydney's transport network" without the minister signing off on the action.
"There are giant holes in the transport minister's story," Ms Haylen said.
A dossier from Mr Perrottet's office confirmed the transport minister had known about the shutdown from 10.43pm on Sunday night, she said.
"Either the transport minister is incompetent of running his own department, or he has misled the public and the parliament about his involvement," Ms Haylen said.
On Tuesday the government withdrew its claim against the Rail, Tram and Bus Union in the Fair Work Commission after the union asked to see the justification for shutting down the network.
Trains resumed at limited capacity on the same day, and will continue at the same level of service through to the end of the week.
The government is due to meet the RTBU later this week to discuss a new enterprise agreement.
