One of New Zealand's most scenic train journeys is celebrating 30 years of taking passengers across the country.

KiwiRail's iconic TranzAlpine train journey has grown from humble beginnings to become one of the country's most popular attractions with local and overseas tourists, said KiwiRail chief executive Peter Reidy.

"The idea for the TranzAlpine was born more than 30 years ago after it became clear how much passengers on our Christchurch-to-Greymouth service enjoyed the scenery on their journey," he said.

In November 1987, the first TranzAlpine Express began running.

Carriages were refurbished, a buffet service and alcove-style seating were introduced, and the viewing experience was enhanced with panoramic windows.

These days, the train has an open-air viewing platform and commentary.

The service has become a New Zealand icon that has been named among the world's top train journeys by National Geographic and The Travel Luxury Expert.

The TranzAlpine carries around 55,000 passengers a year into Greymouth, and West Coast Tourism estimates that it brings around $15 million per annum to the region.

TRANZALPINE FACTS

* Journey between Christchurch and Greymouth takes just under five hours

* 16 tunnels, the longest of which is the 8.5km Otira Tunnel

* The first open-air observation platform was added in 1991

* In the 12 months to June, the TranzAlpine carried approximately 110,000 passengers

* It's travelled around five million km in the last 30 years.

- NZ Newswire