SaHF DMBC Volume 1 Edition 1.1.pdf - Shaping a healthier future

Figure 9.15: Example travel time maps
S-curves
The travel model was also used to produce „S-curves‟. This is a graph that plots all the travel
times to a specific hospital or hospitals for a particular region. The curve starts at the bottom
of the graph (the x axis) with the shortest possible journey and then cumulatively adds on all
the other possible journey times up to the very longest travel time at the top of the graph.
This means the graph can be used to show the percentage of the population that can reach
their destination within a specified time. See Figure 9.16 of an example S-curve.
Figure 9.16: Example travel time maps
Outcomes of the travel analysis
Figure 9.17 shows the travel maps for all the boroughs in NW London. The areas shaded in
the darkest blue would experience an increase in travel time of between 6 to 34 minutes, if
residents there had to go to their „next nearest‟ hospital. The maps showing the current
configuration minus either Northwick Park or Hillingdon have the greatest amount of area
shaded, demonstrating that a larger area (and therefore significant population levels) would
have to travel further if either of these hospitals were no longer major hospitals. This is in
comparison with the maps for St Mary‟s, Chelsea & Westminster and Charing Cross, where
the area of impact is much smaller (refer to Appendix K for further details).
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