AN UNUSED train passageway, prevented by past councils from being sold off or developed, looms as the likely route of a potential light rail system between Coolangatta and the airport.

The route, once complete, would put the project on the doorstep of the Tweed.

The preservation of the rail corridor for future light rail expansion was a key project in the Gold Coast City Transport Strategy 2031.

Gail O'Neill, Division 14 councillor, said Gold Coast council forked out about $800,000 in its last budget to investigate stage three of its light rail project.

This includes the connection between Coolangatta and the airport.

Tweed MP Geoff Provest said the railway corridor linked to Bay St at the border of Coolangatta and Tweed Heads.

He said about 30% of airport passengers travelled south from its exit doors.

Marion Charlton, Gold Coast Airport chief operating officer, said Coolangatta was a key light rail stop.

"We don't consider the airport as an end point for light rail. Just as passengers should have a seamless connection to the hubs of Broadbeach and Surfers Paradise, they should be able to travel south to Coolangatta in the same way,” she said.

"Locals make up 38% of Gold Coast Airport's total passengers and of these, 26% live in New South Wales.”

Cr O'Neill said the council investigation into stage three of its light rail project would be finished by early April.

"This is my personal view: it would have to go up Coolangatta Rd and then through the cutting and that makes sense to me, it's already there,” she said.

"I'll let the experts work that out but I would say that would be part of the investigation because it's already there... and I'm actually really pleased to hear NSW are coming on board and want to be part of the talks.”

Some have suggested the light rail project could one day connect Tweed to Byron Bay buy Mr Provest shot down such suggestions saying the associated costs would be too great.

He said the NSW Transport Minister had committed to investigate the project and Tweed Shire Council should join discussions.

TSC general manager Troy Green said the rail corridor was the logical route.