3.4 Estimation of health and carbon impacts Because the cost effectiveness of cycling investments are influenced by wider social impacts, estimated health economic and emissions impacts are presented in the PCT. An approach based on the World Health Organization’s Health Economic Assessment Tool (HEAT) was used to estimate the number of premature deaths avoided due to increased physical activity (Kahlmeier et al., 2014). To allow for the fact that cycling would in some cases replace walking trips, HEAT estimates of the increase in premature deaths due to the reduction in walking were also included. The change in walking was estimated based on the assumption that, within a given OD pair, all modes were equally likely to be replaced by cycling. Thus all the non-cycling modes shown in Table 2 experienced the same relative decrease. Trip duration was estimated as a function of the ‘fast’ route distance and average speed. For walking and cycling we applied the standard HEAT approach. Ebikes are not specifically covered in HEAT Cycling but enable faster travel and require less energy from the rider than traditional bikes. Thus we estimated new speeds and intensity values for this mode, giving a smaller benefit for every minute spent using Ebikes than conventional cycles. For more details see the Appendix. The risk of death varies by gender and increases rapidly with age. This was accounted for using age and sex-specific mortality rates for each local authority in England. For the baseline and Government Target scenario the age distribution of cyclists recorded in the 2011 Census was used. New cyclists under Go Dutch and Ebikes were assumed to have the age-gender profile of commuter cyclists in the Netherlands. The inclusion of age specific parameters and mode shift from walking shows how the HEAT approach can generate nuanced health impact estimates using publicly available data. The net change in the number of deaths avoided for each OD pair was estimated as the 17