KiwiRail is embarking on an extensive rebuild of Auckland's railway tracks to prepare the network for the opening of City Rail Link (CRL). A lot of the network is over 100 years old, and needs an upgrade so Auckland Transport and KiwiRail can provide more frequent services and faster journeys.

This programme of work is in addition to the Pukekohe to Papakura (P2P) Electrification Programme, and the City Rail Link.