For more than 150 years, trains have travelled along the banks of the river, first transporting coal and then eventually becoming a tourist railway in 1976.

Now the railway's committee has grand expansion plans to extend its current seven kilometre return journey to be more than 60 kilometres, by getting permission to use the main line through to Penguin.

The committee also wants to run the historic train into the Devonport CBD using an existing platform on the waterfront, but is calling for $8 million in State and Federal government funding to make it all happen.

"This is a tourist icon and Devonport, as far as I can see, is the gateway to Cradle Mountain … look at the tourists that come through there. We want to capture those," Don River Railway president Lynn Laycock said.

"When this project gets off the ground, it will benefit the entire north-west coast."

PHOTO: The railway's committee says expanding the operation will be a "win-win for everybody". (ABC News: Erin Cooper)

Ms Laycock said the plans included a new cafe, improved railway museum and new workshops to care for the historic rolling stock, some of which dates back to the 1800s.

"With the train travelling to Penguin, it'd probably have a two-hour layover so you can imagine how much people will enjoy it…the shops will benefit, hospitality will benefit, so this is a win-win for everybody," she said.

"We're just looking forward to the Government stepping up and helping us with some funding."

'If we don't grow, I don't think we'll survive'The volunteer-run not-for-profit relies on government funding for large-scale upgrades.

The railway's general manager Barry Pickett said funding was needed first to outline costings, then to build the plans — plans he said were key to ensuring the railway's future.

"Getting into Devonport and Penguin has the potential to quadruple our revenue and also creates opportunity for employment and increases visitation," Mr Pickett said.

"If we don't grow, I unfortunately don't think we'll survive long-term and I'd hate to see this site go back to a static site."

PHOTO: The railway is maintained by "thousands of hours" of labour provided by volunteers, the committee says. (ABC News: Erin Cooper)

Mr Pickett said slow upgrades in past years had lacked a clear direction for the business, but that was not the case this time around.

"We need to preserve the history of Tasmanian rail, we also need a cafe to create a real experience for people, we need to develop the shed to store all our equipment and we need to be more interactive with our displays to people have a real fun experience.

"It needs to be more than a train trip."

Govt considering funding applicationMs Laycock said the committee had shown Premier Peter Gutwein and several Government ministers around the railway in the past year and the expansion plan had been well received.

A Government spokesperson said the Government supported the Don River Railway and was considering the committee's funding application.

The railway committee has also been in talks with state-owned TasRail, which owns the main line and uses it for freight operations.

PHOTO: Barry Pickett believes "we need to preserve the history of Tasmanian rail". (ABC News: Erin Cooper)

Two high-speed points must be installed on the line for the Don River Railway's trains to access it, which would cost about $1 million.

"TasRail are, in principle, quite supportive of our venture and they will do whatever they can to help us along the way as far as training and accreditation goes," Mr Pickett said.

A TasRail spokeswoman said TasRail and the Don River Railway had a positive working relationship "with a productive dialogue, high levels of support, assistance and encouragement".

"TasRail has a transparent network access process in place and welcomes an application from the DRR and/or any other third party rail operator interested in doing likewise," she said.

Ms Laycock said the Don River Railway was aiming to have passenger trains on the main line by the end of 2022.