NEW Zealand’s national operator KiwiRail will be undertaking a major upgrade of the network in Auckland over the next few years in preparation for the opening of the City Rail Link (CRL), which will enable the frequency of commuter services to be increased.

CRL is now due for completion in 2024 and has been described as New Zealand’s largest infrastructure project to date. It aims to double rail capacity through the city, and requires a preparatory programme of track renewals to remove temporary speed restrictions and upgrade infrastructure to modern standards.

KiwiRail says that its Auckland commuter traffic has experienced considerable growth in recent years, following investment in electrification, new rolling stock and stations. At the same time freight traffic has also increased.

Much of the track is need of renewal and until recently there has been limited funding to carry out this work. To ensure safety an increasing number of temporary speed restrictions have been put in place, increasing journey times for commuters.

With funding from Waka Kotahi, New Zealand’s national land transport agency, KiwiRail has now developed a Rail Network Rebuild programme to improve reliability and ride comfort and enable the frequency of commuter services to be increased with the opening of CRL.

A KiwiRail graphic illustrating the processes involved in strengthening and renewing the track formation for the Auckland upgrade. Picture: KiwiRail

The track renewals programme will include removing the ballast and existing formation, building a new formation to provide a firm and resilient base for the new track and improving drainage.

To complete the majority of work before CRL opens, KiwiRail and Auckland Transport have decided to implement a programme of line closures. This will begin with the Onehunga and Southern lines which will close from January to  March 2023, with the final phases of the programme  on the Western, Newmarket and Manukau Branch lines scheduled for completion in 2025.

A KiwiRail map illustrating the timescale of phased line closures required to undertake the Rail Network Rebuilt through Auckland. Picture: KiwiRail

Under the CRL programme, twin 3.45km tunnels have been completed at a depth of up to 42m below Auckland city centre, connecting Waitematā with Mount Eden on the Western Line via two new underground stations at Karanga-a-Hape and Te Waihorotiu (Aotea).

The tunnel boring machine made its final breakthrough on September 14, meaning both tunnels are built and ready for further works to be carried out.

Construction of the new link line has been delayed, however, by the impact of the Covid-19 pandemic and disruption to the global supply chain, and the CRL project team has been working with design and construction contractor Link Alliance to determine the impact this will have on total project cost and the timescale for completion.