Geografie 1966, 71, 42-54
Inter-Island Transport in Indonesia
Indonesia as an insular state faces a series of problems of inter-island transport of products, covering sometimes distances of several thousands of kilometers. The state measures 5.110 km from West to East, and 1.888 km from North to South. This situation and the fact that the present tonnage or carrying capacity of ships is relatively small, it calls for a most effective inter-island transport. On consulting the map of transport routes, the question arises whether the transport directions of certain products (e. g. rice, cement, fish, copra) are the most advantageous or if it were possible to determine such a plan of transport as to decrease the total costs as much as possible. The present paper attempts at a methodical approach to certain economic-geographical problems by means of calculations of linear programming. We do not know, of course, the detailed inner classification of transported products, e. g. no closer dates on rice are known (whether transported in the from of seed or as a foodstuff). We do not know the total structure of the inter-island transport, the tonnage which is at the disposal in the docks at a certain time, the possibilities of making use of a free cargo space for return passages, etc. Therefore we have rather simplified the main problem in considering the product without its further classification according to quality. We have been speaking of "export" and "import" ports in the inter-island transport, and have considered the transport as a centrally controlled institution, etc. We have avoided, for instance, the transport of goods from manufacturing areas to "export" ports, and from "import" ports to areas of consumption, and a series of further details which -if summed up - can influence the results considerably. In the solution of this problem the so-called modified stepping stone method has been applied. A simple model simulates the transport of homogenous product from supplier D1, D2 ... Dm to consumers S1, S2 ... Sn. Each supplier has a certain capacity, e. g. a1, a2 ... am; b1, b2 ... bn. In our case, suppliers are the "export" ports, consumers are the "import" ports. For the up of the model it becomes necessary do determine certain criteria according to which advantages or disadvantages of the transport should be appreciated. The simplest criterion known is the length of the transport. Distances will be marked with general symbols c11, c12 ... cmn. Before the application of the optimalization method, we have to find the so-called basic solution which is usually quite simple. We can use, for instance the "northwest corner method". In most cases the basic solution is not optimal. Consequently, after the initial basic solution we apply the methods of approximation the simplest of which is the indexing method. To finish the solution of the problem, the method of distribution is applied, which tests the optimum, determines the variety at exit and is concerned with the transformation of the solution. The above example is a simplified model of reality. Nevertheless the results of the calculations are of interest for the economic geographer, as shown in the enclosed maps and table.
