this infrastructure be built? The central purpose of this paper is highlight the potential of online, interactive and publicly accessible tools to improve the provision of locally specific evidence about where cycling has the greatest potential to grow for transport planning. It does so with reference to the Propensity to Cycle Tool (PCT), an online planning support system funded by the UK’s Department for Transport to map cycling potential (Department for Transport, 2015). The PCT is open source. This differs from other tools for assessing cycling potential (see the next section) and has wider implications for how models can and should be used in the transport decision making process (see the Discussion). 

## 2 The Propensity to Cycle Tool in context 

The PCT was developed alongside two branches of academic research: a) methodological developments for estimating cycling potential and b) Planning Support Systems (PSS). The subsequent overview of this policy and academic landscape places the PCT in its wider context and explains its key features. 

## 2.1 The policy context 

A number of factors influence the attractiveness of cycling for everyday trips (Parkin, 2015; Pucher et al., 2010). However, the intervention that has received the most attention has been the construction of new cycle paths. In the UK context, devolved transport budgets mean that local authorities have some control over the design and implementation of cycling networks. While much of the road network budget allocated centrally, through Highways England, cycle paths tend to be commissioned and designed locally due to funding streams such as the Local Sustainable Transport Fund, described in the context of modal shift to cycling by Chatterjee et al. (2013). This, and the shorter distances and more flexible routes (e.g. through parks and along disused railways) that cycle paths can take increases the 

