Beginning as the New Zealand Railways Corporation's Cityline division as a result of restructuring in the 1980s, in its final form Tranz Metro was the operator of Metlink's suburban trains owned by the Greater Wellington Regional Council in the Wellington Region of New Zealand.

[8] In 2004, Toll Holdings bought a majority shareholding in Tranz Rail and renamed the company Toll NZ, and on 1 July 2008, it was bought (less the Tranz Link trucking and distribution arm) by the government and renamed KiwiRail.

KiwiRail retained ownership of the tracks, platforms, electric traction and signalling systems.

Public consultation in 2005–2006 resulted in some changes of emphasis in the new contract, which runs for ten years from June 2006.

[14] The September 2006 fare rises and section changes were stated to part-pay for a major upgrade of trains and facilities over the next few years in conjunction with regional bus service improvements.

Rolling stock as at 2 July 2016: In 2008-2011, KiwiRail and GWRC undertook a major upgrade of the Metlink network, dubbed the Wellington Regional Rail Programme (WRPP).