Buses will replace trains from February 11-14 when the Australian Rail Track Corporation (ARTC) carries out a major maintenance shutdown.
The shutdown will affect the rail network from the port of Newcastle through to Narrabri and out to Ulan, with overnight outages on the passenger network from Islington to Maitland.
It is expected to start at 6.30am on Tuesday, February 11 and finish at 6.30am Friday, February 14.
Approximately 1200 workers will conduct over 120 maintenance jobs including removing and replacing almost 14km of rail, upgrading about 1.5km of track subgrade across six sites, and routine maintenance and defect removal and various other major upgrades.
ARTC will also welcome the new 120 stone Loram grinder to the Hunter Valley which will improve rail grinding performance.
ARTC group executive Hunter Valley Wayne Johnson assured residents and the community ARTC was focused on delivering a safe maintenance shutdown.
"As days of extreme heat can have an impact on the track, such as causing signal faults, circuit breaks or track buckling due to intense heat conditions, we need to carry out this work to ensure the track remains safe, particularly in recent extreme weather conditions," he said.
"We continue to also carry out spot maintenance as required, to ensure the safety and reliability of the track and limit 'hot works' on these days, such as welding or rail grinding to reduce risk."
Mr Johnson said the work required a total shutdown for work to be carried out as safely as possible.
"Similar to other recent maintenance programs, a scheduled shutdown is required to allow us to access the track for maintenance and upgrades that cannot be done safely when trains are running," he said.
"We thank our customers, commuters and motorists across the network for their patience while we carry out this important planned maintenance program.
"We remind residents to remain vigilant as there may be more vehicle movements in and out of work sites in residential areas around the work sites."
Details and schedules for bus services can be found at the Transport for NSW website.
The next major maintenance shutdown is scheduled from April 1-3.