(Figure 3.1B) or to maximize traffic (Figure 3.1c). If we assume that the direct distance from i to j is 1.0, and from that the maximum traffic generated in toto the intermediate towns (open is 1.0, circles) and industrial cities (closed circles) then the first solution traffic 0.61 solution increases reduces to and the second the rail-length to 1.46. An intermediate compromise (Figure 3.1D) linking only the industrial centres keeps the traffic to 0.85 and increases rail-length to only 1.32. The value of this early analysis lies not in its absolute findings so much as in its illustration of the kind of locational problems faced in route construction. The actual values used by Wellington were of doubtful accuracy even for nineteenth-century Mexico, and like von Thien's ring distances (Chapter 6, their use is largely illustrative. Railway location was largely a problem for the middle and late nineteenth century rather than today, and we should perhaps view the rationale of railroad location over most of the world's railroad systems in this historical context.