A benchmark that measures levels of access could be applied to evaluate the links between access to opportunities and social development in cities. This target, aiming to "provide access to safe, affordable, accessible and sustainable transport systems for all", is supported by the infrastructure-based indicator 11.2.1, measuring the proportion of the population with convenient access to public transport, by sex, age and persons with disabilities (UN, 2016). This indicator is based on the assumption that access to infrastructure relates to access to opportunities. While it is useful, measuring and tracking progress in achieving SDG 11, as well as other SDGs (e.g. SDG 4.3, "ensure equal access for all women and men to affordable and quality technical, vocational and tertiary education, including university"), could be enhanced by incorporating other indicators that measure access to jobs, health and education via motorised and non-motorised modes (OECD, forthcoming).