ACCIONA has achieved the highest Design score ever awarded under the Infrastructure Sustainability rating program in Australia, for the NSW Government’s Western Harbour Tunnel project (WHT).

Scoring 101.1 out of 110, the WHT project has received an IS v1.2 Design Rating of Leading, reflecting the project team's commitment to embedding sustainability across every stage of planning and design.

The 6.5-kilometre WHT tunnel is Sydney’s first new road crossing of the harbour in more than 30 years. ACCIONA is delivering stage 2 of the tunnel, which includes excavation of 4.8 kilometres of traffic tunnels from Birchgrove to Cammeray, including under Sydney Harbour, and the complete tunnel fit out.

Project Director Andrew Marsonet, emphasised ACCIONA’s commitment to sustainability, which was reflected in this outstanding IS Rating Certification.

“At Western Harbour Tunnel, sustainability remains a guiding principle that reflects our early commitment to lead with a ‘regenerative by design’ mindset.

"Through empowered leadership and holistic decision making, our focus on leaving behind a positive legacy for our community and environment continues to shape everything we do – from design to delivery,” Mr Marsonet said.

The rating recognises a 42 per cent reduction in potable water use, saving approximately 2,560 megalitres over the project’s design life. Significant carbon savings were achieved by a 35 per cent reduction in life cycle material impacts, driven by early collaboration with design partners.

Key innovations included removing an entire floor from the Cammeray Ventilation Building, optimising tunnel panel design using durable local materials, and embedding value‑engineering initiatives across the project.

The WHT project creates enduring benefits beyond the infrastructure itself. The design approach taken by the team has seen Berrys Bay being revitalised into accessible public parkland, supported by marine research to guide future ecosystem restoration.

A partnership with Corrective Services NSW has created employment pathways for women, while collaboration with Aboriginal artists Dennis Golding, Taleena Simon and local Elders has embedded cultural narratives into the tunnel through the Passing Knowledge artworks, honouring connections between Cammeraygal and Wangal Country.

The ISC Rating Scheme is Australia’s leading framework for assessing the economic, social and environmental performance of infrastructure projects across their lifecycle, from planning and design through to construction and operation.

Projects are assessed across a wide range of sustainability areas including governance, procurement, ecology, discharges to air, land and water, legacy outcomes, and stakeholder engagement.

Within each category, projects must demonstrate compliance with detailed sustainability “credits”, supported by evidence. These credits are weighted depending on project context. For example, ecological considerations may carry greater weighting where infrastructure is located near sensitive habitats.

Achieving such an outstanding IS design rating demonstrates that the Western Harbour Tunnel exceeds best practice sustainability benchmarks and highlights ACCIONA’s leadership in embedding sustainability, innovation and cultural value into complex infrastructure design.