The proposal, by independent railway experts associate professor Philip Laird of the University of Wollongong and Max Michell, was made to the Ausrail conference in Sydney last week.

The plan has also been included in a national railway magazine Railway Digest this month.

It proposes replacing curves with straighter track at three major sites, between Rydal and Tarana, Locksley-Brewongle and Newbridge-Blayney along with smaller changes at other sites.

While it was not costed they said the plan would lift the average running speed from 68 km/h to 84 km/h.

They said the western railway line was not only the slowest in NSW but also much slower than regional train services in Victoria, Queensland and Western Australia which had all benefited from upgrades including realigning the track.

Orange Rail Action Group chairman Dr Peter Bilenkij welcomed the research.

He said realigning the tracks was vital for the transit times between Orange and Sydney to be improved.

"This is independent of government, it's a step in the right direction," he said.

Dr Bilenkij said even when the new regional train fleet was introduced in 2024 the trains could not travel much faster than the current trains if the track was not realigned to allow higher speeds.

He said the proposal came as both the federal and state governments were conducting studies and research into providing fast rail services in NSW - including the main western line.

ORAG's efforts, along with the Orange City Council, to improve rail services to Orange were acknowledged in the report.

The experts said the western main line was actually a lot straighter when it was first laid than it is at present.

However, because of difficulties for steam trains to climb the gradients extra curves were built into the line by the 1920s.

This added 15 kilometres and many slow curves to the railway.

They said with modern, more powerful, diesel trains the line could be straightened, in some cases re-using the original route.

The state government last year announced the construction of two passing loops, at Georges Plains and Rydal, to maintain travel times and cut delays.