Double-decker trains should not have been introduced, says Barry O'Farrell, in comments that repudiate much of the past 40 years of rail planning in the city.
The Premier was speaking at a press conference in Sydney's north-west on Monday, where his government is building an $8.3 billion train line that will never be able to accommodate double-decker trains.
"One of the decisions I think state governments got wrong decades ago was to move to double-decks, instead of matching what's happening in Paris, in London, where single-deck were retained," Mr O'Farrell said.
"Single-deck ... can carry more people, travel more quickly, and disembark those people more quickly without people having to come down those difficult steps that exist on our double-decks and that delay people at railway stations."
The North West Rail Link, to run from Cudgegong Road past Rouse Hill to Epping and then Chatswood, will be Sydney's first privately-operated commuter rail line.
The twin 15-kilometre tunnels for the project are being built with a six-metre internal diameter – too small to fit Sydney's existing double-deck fleet.
In time this will mean much of the rest of Sydney's train system will also need to change to single-decker trains. The government plans to extend the North West Rail Link past Chatswood station through the city in another harbour crossing, linking it to the Bankstown Line and the Illawarra Line to Hurstville.
"One of the decisions I think state governments got wrong decades ago was to move to double-decks, instead of matching what's happening in Paris, in London, where single-deck were retained."
But the insistence on building the North West Rail Link with smaller tunnels is controversial. The Beecroft-Cheltenham Civic Trust, for instance, is planning a public meeting for Tuesday morning to protest against the decision.
And the claim by Mr O'Farrell and Transport Minister Gladys Berejiklian that single-decker trains can accommodate more people than double-deckers is also contested.
Fairfax Media has in the past reported on analysis commissioned by Transport for NSW that shows that single-decker trains do not carry more people.
Mr O'Farrell prefaced his comments on Monday by saying they would be "controversial".
"There are more commuters going into London than come into Sydney and they're catered in good comfort by single-deck trains," he said at the press conference at Bella Vista to announce tunnel machines would be in the ground for the North West Rail Link by October, earlier than anticipated.
Double-decker trains were first introduced to Sydney in the mid-1960s. The silver double-decker S-Sets, which still run on Sydney's train system, were introduced in 1972.
The last single-decker trains in Sydney – popularly known as "Red Rattlers" - were withdrawn in 1992.
At a cost of almost $60,000, Ms Berejiklian and two department officials visited London and Paris last year. Paris, in fact, runs large numbers of double-decker trains on its "RER" lines, which run longer distances than the city's metro system.
Asked about the fact that Paris is expanding its fleet of double-decker trains, Ms Berejiklian said: "In Paris they have single and double-deck trains for long distances. Some of the newest long-distance trains being built around the world are actually single-decks, so in Paris I saw both the doubles and the singles."
She said the government's plans for Sydney's train system included a mix of double-deck and single-deck trains.
At the press conference on Monday, Mr O'Farrell and Ms Berejiklian said Transport for NSW would target western Sydney workers for the mammoth North West Rail Link project.
The train line will include eight new stations and 4000 commuter car parking spaces, and is planned to open in 2019.
The government's hand-picked chief executive of Sydney Trains, Howard Collins, has said he had warmed to Sydney's double-decker trains.
"Let me be a little bit controversial here, because you've got to be a bit," Mr Collins told a business lunch last year.
"Double-deck trains – go to Paris – see how the RER pounds those trains at 24 trains an hour. The design is different, they're still double-deck, but there are solutions," he said.
Mr Collins said he initially wondered what Sydney was doing with so many double-decker trains.
"I've sort of become a little bit warm to them already," he said.
The most recent double-decker trains ordered by the NSW government were the Waratah trains, ordered in 2006.