Key Points:

Travel time between Queenstown and the Milford Sound could be cut if a proposal for a train running through a 13.5km tunnel is accepted.

The Milford Sound Link Rail Ltd proposal would ferry up to 500 people and vehicles on a roll-on, roll-off electric powered train under the Humboldt Mountains from beside the Dart River bridge in Routeburn Rd, to Gunns Camp in the Hollyford Valley Rd, the Otago Daily Times reported today.

Passengers would remain in their vehicles while the train travelled through the tunnel.

Milford Sound Link Rail Ltd chief executive and director Greg Harris said the project had been four years in the planning, and it would be three to five years, provided the company got approval, before the project could start operating.

The departure site, beside the Dart River bridge, was outside a national park, so was not bound by national park laws.

The site at Gunns Camp was in Fiordland National Park, but Mr Harris said it was not insurmountable to get approval for the area.

Facilities would be basic at each departure point, and there would not be a large car park.

There would be one 300m-long train, with locomotives at each end, and the entire trip from Queenstown to Milford Sound would take about two hours, with 12-15 minutes on the 600-tonne train, he said.

"Trains are far safer than cars and buses. People have to stay inside their vehicles and the operators can have more control over them" Mr Harris said.

"Instead of people sitting on a bus for 12 to 13 hours, they can do it in half a day and go somewhere else.

"This can give the industry a real boost."