number of deaths avoided due to cycle commuting minus the number of additional deaths due to reduced walking. Note that this approach means that for some OD pairs where walking made up a high proportion of trips, additional deaths were incurred. The monetary value of the mortality impact was calculated by drawing on the standard ‘value of a statistical life’ used by the Department for Transport. We also estimated the reduction in transport carbon emissions resulting from decreased car driving in each scenario. This again relied on the assumption that all modes were equally likely to be replaced by cycling. The average CO $^{2}$-equivalent emission per kilometre of car driving was taken as 0.186 kg, the 2015 value of an ‘average’ car (DEFRA, 2015). The data analysis and preparation stages described in the previous sections were conducted using the national OD dataset for England as a whole. By contrast, the stages described in this section were conducted using a region-by-region approach. Transport decisions tend to be made at local and regional levels (Gaffron, 2003), hence the decision to display results on a per region basis. Figure 3 shows the output: ‘desire lines’ lines with attributes for each OD pair aggregated in both directions (Chan and Suja, 2003; Tobler, 1987), and visualised as centroid to centroid ‘flows’ (Rae, 2009; Wood et al., 2010). ## [1] FALSE Desire lines allocated to the route network are illustrated in Figure 4. This shows two route options: the ‘fast’ route, which represents an estimate of the route taken by cyclists to minimise travel time and the ‘quiet’ route that preferentially selects smaller, quieter roads and off road paths. ## [1] FALSE 18 3.5 Visualisation, route allocation and network generation