score: (ii) select probable vertices to be linked from this list of settlements by a randomization (iii) connect the two largest vertices by a rail link; (iv) process; add the other in such that the next largest centre joins the edges sequence largest and closest centre which is already located on the network (Kansky, 1963, p. 138). after all the vertices have been connected to the railroad system, un-allocated links remain, then, (v) add the links in such a way that the circuit between the first, second, and third largest centres is completed, and continue to complete the circuits bringing in the fourth, fifth and lower order centres in turn. The map of routes may be finally adjusted by (vi) the adoption of delta-wye (A n transformations (Akers, 1960) to simplify the links between triangles of three points, and (vii) local adjustment of the routes to physical variations in the relief Kolars and Malin (1970) have developed the Kansky model by using the population within twenty miles of selected points to identify ridges of high population potentials; such ridges were then incorporated into the model as generators of route links on the railway system.