The Propensity to Cycle Tool: An open source online system for sustainable transport planning Robin Lovelace (University of Leeds) Anna Goodman (London School of Hygiene and Tropical Medicine) Rachel Aldred (University of Westminster) Nikolai Berkoff (independent web developer) Ali Abbas (University of Cambridge) James Woodcock (University of Cambridge) Getting people cycling is an increasingly common objective in transport planning institutions worldwide. A growing evidence base indicates that high quality infrastructure can boost local cycling rates. Yet for infrastructure and other cycling measures to be effective, it is important to intervene in the right places, such as along ‘desire lines’ of high latent demand. This creates the need for tools and methods to help answer the question ‘where to build?’. Following a brief review of the policy and research context related to this question, this paper describes the design, features and potential applications of such a tool. The Propensity to Cycle Tool (PCT) is an online, interactive planning support system which was initially developed to explore and map cycling potential across England (see www.pct.bike). Based Abstract arXiv:1509.04425v3 [cs.CY] 15 Mar 2017 1