Designing Australia’s largest public transport project to withstand a changing climate
The Sydney Metro Northwest is Australia’s largest public transport project and a priority infrastructure investment for the New South Wales Government
We integrated sustainability principles throughout the project and collaborated with multiple stakeholders – clients, public authorities and communities – to minimise the metro’s carbon footprint.
We developed the project and the overall Business Management System based on the outcomes of a Life-Cycle Assessment (LCA) and a project-specific Climate Change Risk Assessment and Adaptation study. Additionally, we introduced a holistic approach to sustainability on site, ensuring that decision-making included environmental, social and economic perspectives at every step: design, procurement and construction.
In particular, in the design phase, we considered the climate change risks related to more frequent and extreme heat waves, higher annual temperatures, increased rainfall intensity, flooding, wind, storms, lightning and hail. For each risk, we identified design solutions to help make the project more resilient.
For example, we designed the foundations of the viaducts and bridge to withstand to a 2000 years flood event, and specified the size of culverts and catch drains to account for a 10% increase in rainfall intensity. Additionally, given the projected increase in mean wind of 10% by 2100 in the area, we designed the viaducts and bridge to withstand extreme gusts of wind of 173km/hr. That is 47% greater than the maximum recorded wind speed in Sydney.
Using the LCA results, our project team identified a set of focus areas with related sustainability targets to be included in the design phase and then integrated with procurement, workforce and construction processes. These include: Climate Change; Carbon Management and Energy Efficiency; Community; Water Efficiency; Waste and Materials; Land Use and Biodiversity; Pollution Control; Workforce Development; Sustainable Procurement; Temporary Site Facilities; Innovations.
The targets range from energy saving (-5% of diesel and electricity consumption in comparison with the standard design) to water (minimum 50% replacement of drinking water with non-drinking water), waste recycling (90% of construction waste to be reused or recycled), low-carbon steel (60% of reinforcing bars and meshes produced through recognised energy reduction processes) and carbon reduction (-2.5% of GHG emissions). Modelling demonstrates a reduction in materials lifecycle impacts of 44%.
Social targets include a minimum value of supplies to be drawn from local businesses (at least 160), employees to be hired from the local community (minimum 20%), development and diversity targets (at least 15% of trainees and minimum 2% of employees from disadvantaged groups).
To engage our supply chain, we integrated key sustainability criteria in our procurement checklists, asking potential suppliers to respond to a sustainability questionnaire in the tender process and arranging workshops to explain our requirements.
Finally, we monitored day-to-day construction activities to review performance against our sustainability policies and requirements, tracking results in real time.
Infrastructure Sustainability Rating
We sought independent verification of our progress via the ISCA IS Rating Tool. This is an Infrastructure Sustainability (IS) scheme developed by the Infrastructure Sustainability Council of Australia (ISCA). It verifies and validates the successful delivery of environmental and social sustainability initiatives throughout the project lifecycle.
The IS Rating is determined by a score out of 100 and has three rating levels: “Commended” indicates that a project is achieving better than ‘business as usual’; “Excellent” recognises Australian best practice; and the “Leading” rating indicates “World-Class Best Practice in Sustainability”.
In October 2015, Salini Impregilo was awarded the “Leading” IS Design rating in recognition of the collaborative efforts of our project team in Sydney and our design partner SMEC to integrate sustainability at the heart of the project.