evidence base, we hypothesise that tools such as the PCT can encourage informed and rigorous debate, as advocated by Golub et al. (2013). In conclusion, the PCT provides an accessible evidence base to inform the question of where to prioritise interventions for active travel and raises more fundamental questions about how models should be used in transport planning. 

## Author contribution statement 

The PCT was built as a collaborative effort. The Principal Investigator of the project was JW, and the initial concept for the project came from JW and RL in response to a call from the Department of Transport. AG led the creation of the model underlying the PCT, and the generation of estimates of cycling levels, health gains and carbon impacts in each scenario. JW and AG led the development of the methods for calculating health impacts. JW, RL, AG, and RA contributed to the development of the cycling uptake rules. RL led the processing of these modelled estimates for spatial visualisation in the online tool and coordinated the development of the online tool. RA led the coordination of policy implementation and collection of practitioner feedback. AA and NB led on the user interface, with contributions from all authors. NB led the deployment of the PCT on a public facing server. AG led the writing of the Appendix. RL led the writing of this manuscript, with input from all authors. 

## Acknowledgements 

We would like to thank the following people for comments on earlier versions of the manuscript and the development of the PCT: Roger Geffen (Cycling UK), Tom Gutowski (Sustrans), Helen Bowkett (Welsh Government), John Parkin (University of the West of England), Nikée Groot and Phil Tate. Thanks to Simon Nutall and Martin Lucas-Smith for access to and 

