City Rail Link sets new sustainability benchmark with leading ISC ratings
Aotearoa New Zealand’s most significant infrastructure project, the City Rail Link (CRL), has achieved a landmark sustainability milestone, receiving two Leading As-Built ratings from the Infrastructure Sustainability Council (ISC) under its IS Ratings scheme – the only comprehensive rating system in Australia and New Zealand for evaluating the economic, social and environmental performance of infrastructure across planning, design, construction and operation.
These ratings make CRL the first project to earn a Leading IS As-Built rating, officially recognising the entire project, stretching from Waitematā to Maungawhau, as meeting the highest sustainability standards ever achieved on either side of the Tasman. The IS system is used to assess projects across a wide range of sectors, including roads, water, rail, energy, airports, ports and social infrastructure. To put this achievement into perspective, CRL is the only New Zealand rail project among 80 assessed in the sector, including high-profile projects such as the Sydney Metro and Melbourne Metro programme. This recognition is a significant achievement for Auckland and for the teams involved.
CRL’s awarded ratings:
- Leading As-Built rating for the overall CRL project, covering design and construction of the C1, C2 and C3 contracts, comprising the 3.45km route of tunnels and stations.
- Leading As-Built rating for the design and construction of CRL’s main C3 tunnels and stations, including Te Waihorotiu, Karanga-a-Hape and Maungawhau Stations, and the tunnel boring machine works between Maungawhau and Te Waihorotiu.


ISC Chief Executive Toby Kent commended the achievement, saying: “The ISC is proud to see New Zealand’s biggest transport infrastructure project adopt sustainability into the DNA of its operations. This has been an amazing achievement and demonstrates the overwhelmingly positive social, economic and environmental good that is possible to achieve through an IS Rating.”
CRL Ltd Chief Executive Patrick Brockie said the independent assessment is a powerful endorsement of the values and hard mahi adopted and demonstrated by the project, contractors and subcontractors from day one. “Success for CRL Ltd and our Link Alliance delivery partner is testament to the passion, commitment, and tenacity of the many talented people who have delivered a project that is not just good for Tāmaki Makaurau Auckland, but good for the sector, shifting the needle on how we integrate sustainability, environment, social outcomes and culture into large scale infrastructure projects.”
The rating was earned through a number of initiatives aimed at raising the project’s environmental and social performance. Resource efficiency was central with over 97% of construction and demolition waste and 100% of spoil diverted from landfill. Over the project’s 100-year lifespan, design and construction strategies are expected to delivery significant long-term efficiencies, including:
- 17.8% reduction in peak operational energy use
- 23% reduction in operational carbon emissions
- 58% reduction in operational water use
Through partnership with the Mana Whenua Forum, nominated designers have brought to life cultural narratives in the public realm, most notably through the creation of Te Komititanga. Participation in CRL Ltd’s Progressive Employment Programme pilot provided opportunities for Māori and Pasifika youth to gain valuable experience across construction sector roles.
“Te Ao Māori has environmental sustainability at its very core,” says Edith Tuhimata, from the project’s Mana Whenua Forum, “and we have an inherent responsibility to future generations for the way we conduct our businesses and the impacts that has on the environment and the people, if we take care of the Taiao (environment), the Taiao will take care of us. Mana Whenua bring a holistic approach to the CRL project to ensure whakapapa links are acknowledged and the best practical environmental, sustainable, social and cultural outcomes are achieved.”


The contracts included in the ratings are:
- C1 – Waitematā Station/Lower Queen Street and Commercial Bay: designers Aurecon, Mott MacDonald and Jasmax; delivered by Downer and Soletanche Bachy Joint Venture.
- C2 – Northern end of Albert Street between Customs Street/Commercial Bay and Wyndham Streets: designers Aurecon, Mott MacDonald, Grimshaw, Jasmax, Arup; delivered by Connectus (McConnell Dowell and Downer Joint Venture).
- C3 – Main Tunnel, Stations, Western Line Connection and Rail Systems, delivered by Link Alliance (Vinci Construction Grands Projets, Downer, Soletanche Bachy, WSP, AECOM, Tonkin+Taylor and CRL Ltd).
Under the C3 contract, Jasmax worked in collaboration with Mott MacDonald, Arup and Grimshaw, as part of the Principal Technical Advisory led by Aurecon, to develop the reference design for CRL. Jasmax is now undertaking an Owner Verifier role, responsible for ensuring that the Link Alliance construction consortium delivers the project in accordance with the reference design.