Sustainability is important for many reasons, but fundamentally it is not about what we should do for the environment, it is something we must do to preserve our quality of life and of all life on the planet. It is particularly important for road tunnels because compared to a road at grade, a road tunnel has a substantially larger carbon footprint due to the significant efforts required to build a road tunnel, and the nonstop operation of its systems through its life cycle. In Australia and New Zealand, governments have committed to achieving net zero emissions by 2050. Organisations responsible for delivering and operating road tunnel infrastructure will have an obligation to reduce embodied and operational emissions as far as practicable, as the tunnels will exist beyond 2050.