University of Wollongong academic Philip Laird has called into question Infrastructure NSW's aim of a one-hour train trip from Wollongong to Sydney.
In its 20-year strategy for government spending released last week, Infrastructure NSW (INSW) cited a 60-minute train commute as a priority for the region.
The strategy said that some trains in peak hour could make the run in 60 minutes with a combination of measures.
These included trains travelling at faster speeds, tighter timetables, and express trains with fewer stops.
INSW chief executive Paul Broad specifically ruled out massive infrastructure work on the line.
"We're not about tunnels, we're not about big projects, we're about incrementally changing what we've got to do it better," he said.
Associate Professor Laird said while the trains could travel faster and timetable fiddling could bring down the travel time a bit, a one-hour ride was unlikely without some major infrastructure work.
"The timetable does have some slack but not 30 minutes of slack," Prof Laird said.
"The very best we could hope for in the existing timetable is what we had in the late '80s with one Saturday morning train doing it in 75 minutes.
"To get it down to an hour you're going to need infrastructure improvements - either the 12 kilometre tunnel [from Thirroul to Waterfall] as proposed in 1998 or some other track straightening between Waterfall and Thirroul."
While not ruling out the possibility, Prof Laird was sceptical about a one-hour ride on the existing rail line.
"It's not a dream but unless they've spelt out how to do it it does make you wonder," he said.
"More detail is needed from them to give confidence to the claim."
Prof Laird also noted that the INSW report mentioned the Maldon-Dombarton line which he said could play a part in a faster rail trip by removing freight from the Sydney-Wollongong line.
"It's a good thing that they recognised Maldon-Dombarton," he said.
"But there's a case for it to be built this decade rather than the 2020s."