The section from Hindon to Pukerangi held special appeal, Project Steam member Richard Emerson said.
The vision of "pioneering preservationists" went beyond allowing the scenic wonders of the gorge to be appreciated by cycling and walking enthusiasts to preserving the railway for all people of varying abilities and disabilities, he said.
Feasibility of extending the popular Otago Central Rail Trail past Middlemarch towards Dunedin is to be looked into.
If established, a cycle trail might run from Middlemarch to Outram, including alongside some of the track and using an old walking trail but unavoidably clash with the rail line between Hindon and Pukerangi.
Tourism trains from Dunedin in recent times have mostly run only as far as Hindon.
However, aspirations for restoring train services to Middlemarch have remained.
"The journey by train to Middlemarch is a wonderful experience, starting from the classical ‘Gingerbread’ Dunedin Railway Station, rolling along the Mosgiel-Taieri plains, climbing the hills through two long tunnels and joining along the meandering Taieri River to Hindon," Mr Emerson said.
"The highlight of the trip is just around the long bend above Hindon with the railway soaring above the Taieri River, climbing along the scenic rocky gorge to plateau out at Pukerangi.
"From there, the passengers can appreciate the Strath-Taieri vista and the majestic Rock and Pillar Range before ending at Middlemarch."
Project Steam is a society focused on restoring steam locomotives and heritage rolling stock, but it also has a long-term vision to run a tourism train between Middlemarch and Sutton, and possibly further.
Mr Emerson said having a scenic railway at its doorstep was a point of difference for Dunedin.
"And once the line is gone, it’s gone forever."
The Dunedin City Council has shown willingness to retain the line and a train service on it.
However, it has yet to work out how this should be structured and it has also endorsed the cycle trail feasibility work.
The Otago Central Rail Trail Trust, which commissioned the cycleway extension feasibility analysis, said it had worked with Project Steam to ensure the heritage line between Middlemarch and Sutton, and potentially to Pukerangi, remained available.
"But having assessed the line between Pukerangi and Hindon, there is no opportunity to have both a train and cycle service that could operate together," trust chairwoman Kate Wilson said this month.
The trust wanted to make sure the council had all relevant facts before it when making decisions about train assets and "has offered to undertake the feasibility to ensure all the information on the options is available".
Running a train service — and being responsible for the Taieri Gorge track — has effectively been a loss-making exercise for council-owned Dunedin Railways, as deferred maintenance became a multimillion-dollar issue.
The council has in recent months not talked publicly about the extent of track maintenance needed, because of commercial sensitivity.
Mosgiel-Taieri Community Board chairman Andrew Simms said at a board meeting last week the council essentially had control of the railway corridor for decades to come and nothing precluded it from becoming a cycle trail.
It was up to the council and community to work out how the asset might best be used, he said.
"The greatest thing we can hope for is a transparent discussion of the whole matter."
