12 Figure 1: Flow diagram illustrating the input data and processing steps used to create the input data used by the PCT. The abbreviations are as follows: HEAT = Health Economic Assessment Tool, OD pair = origin-destination pair, MSOA = Middle-Layer Super Output Area Exclude within-zone  flows, and pairs not  meeting additional  distance/size criteria Dataset 2:  Background mortality  rate for cyclists, merge in at the  local authority level Dataset 1:  Origin-destination (OD) pairs at the MSOA-level for  all commute trips in England and Wales, stratified by method of  travel to work and by gender, from the 2011 Census Data processing (details in Appendix) 1. Collapse flows >30km fastest-route distance, or ending  outside England or Wales, into an ‘other’ category.  2. Estimate distance and hilliness for OD pairs that start and  end in the same zone Assign cycling distance to ‘no fixed  workplace’ / ‘other’ flows  3. Apply propensity to cycle equations : generate changes in  cycling in each OD pair in 4 scenarios. Calculate changes in  walking/driving in 4 scenarios. 4. Calculate HEAT for health benefits. 5. Calculate CO$_{2}$ reductions. Dataset 3:  Fastest route distance  (km)/hilliness (% incline) of each  OD pair <30km Euclidean  distance, from CycleStreets.net. Aggregate to bidirectional OD level • Make bidirectional-totals for each OD  pair ,and collapse dataset. • N=718,455 unique bidirectional OD  pairs, 23,903,549 commuters. Aggregate to area level • Make area-level totals and  collapse dataset. • N=7201 unique MSOAs,  23,903,549 commuters Visualise desire lines in  the user interface, &  allow data download Model parameterisation draws on  analysis of the national dataset of  OD pairs; analysis of the UK,  Dutch and Swiss National Travel  Surveys; and published guidance  on HEAT and other sources. Visualise areas in the  user interface, & allow  data download. Visualise Route  Networks in the user  interface Allocate OD  pairs to routes Visualise fast/  quiet routes in the  user interface Subset OD pairs for regional builds • Exclude pairs that cross regional  boundaries, or have no fixed workplace. • Exclude pairs according to adjustable  criteria on maximum distance and  minimum number of commuters.