Gunnedah trains will be replaced with buses next week because of track maintenance and enhancement work.
The works will occur on the main line between the port at Kooragang in Newcastle and Narrabri, and the Ulan line west from Muswellbrook, from 6.30am Tuesday, May 21 and 8.30pm Thursday, May 23.
ARTC's Jonathan Vandervoort said the maintenance involved about a thousand workers undertaking 122 jobs to help deliver service reliability.
"Similar to other recent maintenance programs, a scheduled 62-hour shutdown is required to allow us to access the track for maintenance and upgrades that cannot be done safely when trains are running," Mr Vandervoort said.
Works include ballast cleaning, re-railing, track reconditioning, and enhancements to signalling systems on the Bengalla to Mangoola section on the Ulan line and on the Werris Creek to Burilda section on the main north line.
These signalling system enhancements will provide increased availability of the network on those lines.
"We apologise for the inconvenience and as always we appreciate the patience and cooperation of motorists, commuters and customers right across the maintenance program," Mr Vandervoort said.
"We also 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."
Details and schedules of the alternative bus services can be found on the Transport for NSW website.