The work will begin 6.30am on the Tuesday from the port at Kooragang in Newcastle and along the rail corridor to Narrabri, and the Ulan line west from Muswellbrook.

All works are expected to finish by 6.30am on Friday, April 12.

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ARTC's Jonathan Vandervoort said 124 different jobs and an investment of more than $20 million would go into the works.

"Works will include ballast cleaning, re-railing, track re-conditioning and turnout renewals," Mr Vandervoort said.

"There will also be enhancements to signalling systems along a section between ... Watermark and Turrawan on the North West line, providing increased availability of the network."

Mr Vandervoort said the patience and co-operation of commuters and customers was appreciated during the works.

"The shutdown provides us with the best opportunity to access the track safely for longer periods of time and we plan well ahead to get the major work done during that window," he said.

"We ask people in communities close to the rail corridor to be cautious during the shutdown period and keep an eye out for increased vehicle movements in and out of work sites."

Alternative bus services will be provided during the shutdown, and details and schedules can be found at the Transport for NSW website.

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