Infrastructure threatens to lock-in societies to fossil fuels unless something is done now. This is because infrastructure lasts for such a long time, meaning that any infrastructure built or rebuilt now will last well into the twenty-first century – until the end of the century, in some cases. Consequently, there is a need to integrate climate change into infrastructure now or societies will be left with infrastructure designed around unsustainable socio-technical systems (such as combustion engines, roads, and suburbanization). Such change is conceptualized in the literature as a sustainability transition. However, any attempts at such transitions have to address the ‘materialities’ of infrastructure systems (physical form, environmental context, and so on). In this paper, I develop the concept of ‘socio-material systems’ and apply it to transport infrastructure in Ontario, Canada.