The TranzAlpine is a passenger train operated by the Great Journeys New Zealand division of KiwiRail in the South Island of New Zealand over the Midland Line; often regarded to be one of the world's great train journeys for the scenery through which it passes (see lists of named passenger trains). The journey is 223 kilometres (139 mi) one-way, taking almost five hours. There are 16 tunnels and four viaducts, with the Staircase Viaduct elevated as much as 75 metres (246 ft).

The train has become increasingly popular, and carried 204,000 passengers in the financial year ending 2007. By 2016, passenger numbers were approximately 130,000 a year, but rising again after the setback of the Christchurch earthquake, and were exceeding pre-earthquake levels.

The TranzAlpine service was suspended in 2020 and again in 2021 because of the COVID-19 pandemic, but resumed on 14 January 2022.

The train was introduced on Sunday 22 November 1987 to replace the conventional Christchurch-Greymouth express trains and became one of the New Zealand Railways Corporation's new tourist-oriented passenger services utilising refurbished rolling stock. Accompanying this new-look train were a new-look livery and rebranding.

From late 1982 until 1983, twelve second class NZR 56-foot carriages, three with luggage compartments at one end, were refurbished with new "Supervent" windows, fluorescent strip lights, wall-to-wall carpet, and later still, new seats designed by Addington Workshops were introduced to replace the former articulated diesel-hauled AC class "Grassgrub" carriages. A matching 56-foot van and six 50-foot wooden bogie box wagons for parcels completed the consist. Some of these wagons had served in the same capacity and in the green colour scheme with the Grassgrubs on the Picton and Greymouth routes and one wagon had served the old yellow Northerner as a parcels van, prior to the introduction of the twelve 56-foot carriages. These carriages and wagons, like their Grassgrub predecessors, worked the Picton Express (out and back) and Greymouth or West Coast Expresses (one each way simultaneously). All were painted in a bright red colour scheme.

With the deterioration of the yellow Northerner stock, carriages to replace these had to be found by sourcing from the rest of the NZR 56-foot carriage fleet. The change in service was marked, with a refurbished modular FM van turned power-luggage van with handbrake end-mounted 11 kW petrol generator, and three carriages, one from the Endeavour Express and later Southerner Express converted into a servery car seating 31 in reupholstered Addington Workshops-produced seats, in bays of four with two pairs of seats each facing into a table, arranged alcove-style, with windows over double the size of the old ones, enabling better views of the alpine scenery, reupholstered seats and carpet, and a buffet counter service, to replace refreshment stops at railway station cafeterias at Springfield and Otira. The original intention had been to replace each pair of windows with one larger window, but the final solution was to cut out the side of the carriages and to insert a steel ladder frame to which sheets of strengthened glass were glued. The effect, of a continuous sheet of glass the length of the carriage, was spectacular and undoubtedly was a major factor in the success of the new service. The other two carriages were red Picton – Greymouth carriages that were refitted and repainted to the same standard but retained their smaller windows and seated 50, same seating arrangement and type as the servery car.

Reducing the service to an "out and back" format as opposed to "one each way" freed up carriages for other services, and by refurbishing existing stock it was hoped that the move would draw people to the previously poorly-performing Greymouth passenger trains. The service proved to be popular, with patronage doubling in the first year, with 7,183 passengers in January 1988 alone.

Soon, two more Picton – Greymouth carriages were refitted similar to the servery and observation car, so the two small-window carriages could be slotted into the Southerner consists. These new "big window" carriages each sat 51, same seating arrangement and type as the servery car. In the early 1990s, the first generation TranzAlpine panorama carriages had a new pressure ventilation system installed, similar to the Bay Express and the observation carriage introduced to this train in 1991.