Train services in Sydney's northern suburbs would be disrupted for almost a year before the opening of the north-west rail link, under proposals recently approved by the state government.

In late 2018 and early 2019, the government plans to shut the existing Epping to Chatswood line for seven months to make the line compatible with the sort of trains it will run on the adjoining north west rail link.

Train services will experience disruption for almost a year

But before then, the government is planning to run shuttle trains between Epping and Chatswood for four months, meaning commuters from the city or Hornsby will have to change trains to access stations such as Macquarie Park or Macquarie University.

Transport for NSW says "survey work and inspections" in the existing Epping to Chatswood tunnels have already started as part of a project to convert the train line to what it calls "rapid transit" - single deck trains that will operate without drivers. The department recently granted itself planning approval to undertake this conversion.