The shortcomings on Sydney's stressed train network will be exacerbated by looming "open-heart surgery" at Central Station, according to the State Opposition.

Key points: More than 270,000 people use Central Station every day

More than 270,000 people use Central Station every day NSW Transport Minister says the redevelopment will not disrupt passenger services

NSW Transport Minister says the redevelopment will not disrupt passenger services However, the State Opposition say recent delays prove that is wishful thinking

New South Wales Transport Minister Andrew Constance announced Laing O'Rouke had won the $955 million contract to renovate the station, and that work would begin immediately.

During construction, platforms 13 and 14 will close while underground works commence to upgrade the century-old station, which is Australia's busiest with more than 270,000 people using it daily.

Sydney's train network has been under increased pressure since a new timetable was unveiled in November, which added 1,500 weekly services.

Shadow transport minister Jodi McKay said the "dog of a timetable" would be exacerbated by the works at Central.

A spokesperson for the Transport Minister said platforms 13 and 14 "are not used" in the current timetable.

On December 11, Sydney Trains apologised to commuters after widespread delays during peak hour due to a fatality on the tracks.

The following month, a combination of factors was blamed for a day of chaos across the network in which overcrowding was reported on platforms at several stations, and trains were either hours late, or did not show up at all.

Platforms at Strathfield station were overcrowded during January's delays. ( ABC News: Nour Haydar )

Minister Constance said Central Station's redevelopments would untangle Sydney's train network.

"We will in essence undertake open-heart surgery on Central, and we're going to be able to do so without disrupting passenger services on a daily basis," he said

NSW Premier Gladys Berejiklian was less sure.

"Unfortunately the by-product of building something new means there is temporary disruption and we regret that," she said.

"But that's no excuse for not doing it. It would be negligent of us to sit on our hands and not improve Central Railway Station because it's going to cause some interim disruption."

Work to be finished by 2022

The redevelopment at Central Station will new Sydney Metro underground platforms and a "Central Walk" — a 19-metre wide underground concourse from Chalmers Street connecting heavy rail, light rail, the Metro lines and busses.

Those works are expected to be complete by 2022.

However, after those new Metro tracks will be laid and the station will be fitted out before its opening in 2024.

Central Station in Sydney will be revamped, with escalators to platforms 12 to 23. ( Supplied: NSW Government )

Ms McKay said the blueprint meant problems for commuters.

"The Minister is happy to stand in front of shiny new plans for his Metro but when it comes to the travelling experience of people on a day-to-day basis, he simply doesn't care," she said.

"Every single project that they have underway currently there have been issues with.

"We've got a dog of a timetable that we're working with and that will only be exacerbated by the works at Central."

More than 270,000 people use the station daily, with that number expected to rise to 450,000 in the next two decades.