But the transport body has dismissed it, retaining the location next to the existing stairs as its preferred option.

The previously secret "Option B" was a part of a suite of documents uncovered by Wollongong MP Paul Scully via a freedom of information request.

In 2017, engineering and construction firm Jacobs carried out a "compliance needs analysis" of the projects in the third round of the Transport Access Program.

This included Unanderra and the report looked at two options for the lift location.

Option A was Transport for NSW's preferred position next to the stairs, while Option B would place the lifts closer to the mid-point of the station platform, quite close to the northern car park exit.

Option B would also be closer to the disabled parking spaces at the station.

READ MORE: Govt gives clearer date for Unanderra lifts

The report found the first option "has major impacts on utility services which will be restrictive from both a project program and cost perspective".

Option B - which would require the demolition of the existing stairs and bridge - would "avoid any works in close proximity [to] the existing gas and water services crossing the rail corridor in the vicinity of the existing footbridge."

The location of utilities in the area of the lift pits at the southern end has been part of the reason the project has been delayed for so long.

"It certainly seems that, when it comes to lifts at Unanderra station multiple options have clearly been considered," Mr Scully said.

"For the government to fall back on the excuse of utilities under the ground - the same excuse they used to stop the project in 2011 - is just another case of the government dragging its heels when it comes to finally getting the lifts built at Unanderra station."

A spokeswoman from Transport for NSW confirmed the preferred option is for lifts to be installed on the northern side of the existing footbridge.

"This is subject to community consultation, including the preparation of the Review of Environmental Factors scheduled for early 2020," she said.

The spokeswoman said the utilities issue has been reassessed since the 2017 report.

"Following the initial needs analysis, completed in 2017, Transport for NSW carried out further site investigations, including site surveying and assessment of underground services," the spokeswoman said.

"This determined that it is possible to install the lifts near the existing footbridge, without impacting directly on major underground services such as gas and water mains."