2014-10-14 Planning & Organisation Committee Agenda - Pages 51 - 117

PLANNING & ORGANISATION COMMITTEE MEETING AGENDA   14 OCTOBER 2014




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PLANNING & ORGANISATION COMMITTEE MEETING AGENDA                                                  14 OCTOBER 2014

            The population gravity model was expanded by William J. Reilly in 1931 to create a ‘law of retail
            gravitation’. This aimed to devise a method which might calculate the trading area of a particular
            location/shopping centre. It aims to identify the trade ‘breaking point’ between two places. This is seen as
            the point of ‘indifference’ between the two locations, where customers will be drawn to one or another of
            two competing commercial centres, depending on factors such as proximity, scale and convenience. The
            law presumes the geography is such it does not create significant barriers that would alter a consumer's
            decision of where to travel to buy goods. It also assumes consumers in each city are have similar cultural
            and economic circumstances.

            For instance, as shown in the theoretical example of figure                         My
            3, two locations are 75 km apart. Rather than the ‘break                   45.9 km   | 28.1 km
            point’, or the point of ‘indifference’ being halfway in          —a                     (6)
            between (35 km) the two centres, since location A has a                        7km   \
            larger population (more weight), it is assumed that it will     250,000                     tog,000
            draw more customers. Using gravity modelling principles,              D                        75
            Reilly’s Law places the point of indifference 45.9 km away   Map = ——             Ma = 1+ 9*9°0/50.000
            from location A.                                                   1+    o/p                      250,000
                                                                                       @      Map = 45.9

                                                                                       Distance between   Trade break
            Table 4 — Eumundi confirms the information       Table 4 -Eumundi          each location      point
            illustrated in Chart 3 above.                    creater Nambour     :             21              6
                                                             Coolum/Peregian Springs           24              17
                                                             Noosa-Noosaville                  26              20
                                                             Greater Maroochydore              34              26
            Table 5 — Doonan also confirms the data                                    Distance between Trade break
            illustrated in Chart 4 above                     Table 5 - Doonan          each location     point
                                                             Noosa-Noosaville                  14             10
                                                             Coolum/Peregian Springs           19             13
                                                             Greater Nambour                   28             19
                                                             Greater Maroochydore              35             25
                                                            Table 6 - Verrierdale -   Distance between   Trade break
            Table 6 — Verrierdale/Weyba Downs confirms       Weyba powns.             each location      point
                    ;          .                             Greater Nambour                  27               9
             he data illustrated in Chart 5 ab
            the data  Nlustrate    art > above               Coolum/Peregian Springs          17              12
                                                             Noosa-Noosaville                 18              15
                                                             Greater Maroochydore             31              25

            As a caution, it should be noted the concept of the gravity model has opponents who claim it is only based
            on observation and cannot be confirmed scientifically. It is also claimed the model is an unfair method of
            predicting movement because it is biased toward historic ties and toward the largest population centres.
            However, experience suggests the conclusions reported above are supported by other evidence such as
            shopping patterns and involvement in sport/social clubs and appear to be realistic and relevant, if not
            precisely accurate.

            Ted FitzGerald, June 2014

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