Major construction work is under way at Central Station as part of the Sydney Metro project, in the biggest upgrade to the city’s busiest railway station in decades.

Two underground metro platforms are being built as part of the upgrade, as well as an underground concourse that will help commuters move between the light rail, trains, the metro and buses.

Work is under way to build a 27-metre deep metro station “box”, with about 6000 tonnes of crushed rock being excavated every week.

NSW Transport Minister Andrew Constance says it is fortunate work could continue during the COVID-19 pandemic.

He says there are strict protocols in place to protect construction workers.

“More than 5000 people are currently working across the Sydney Metro City and Southwest project, and by the time the project opens, around 50,000 people will have worked on it,” Mr Constance said in a statement on Wednesday.

“The upcoming Sydney Metro West project will support 10,000 direct and 70,000 indirect jobs.”

Work has broken into Central’s co-called ghost platforms, which were built last century but never completed.

The two unused platforms will house 17 communications and power rooms to support the metro.

The underground concourse is expected to open in 2022 while construction on the Sydney Metro, extending from Chatswood through the city and to Bankstown, continues until 2024.

The new standalone railway will include 31 stations and more than 66 kilometres of metro rail.