The Hunter Valley rail freight lines are to be shut for the next five days.
The move is expected to disrupt coal transport across the region, the Newcastle Herald reports.
According to Australian Rail Track Corporation general manager Alec MacKenzie, the closure will allow for major upgrade work across the 1500 kilometre network.
It is part of the wider strategy top increase capacity of the Hunter Valley line to support the growing demand for coal and the expansion of Newcastle's coal terminals, in particular the construction of the new T4 coal loader.
It is believed that the upgrades will cut down on queuing and congestion on the line.
The work is 'critical to the safety and reliability of the network' MacKenzine added.