ECONOMIES OF THROUGHPUT AND TRANSPORT BOTTLENECKS IN GRAIN DISTRIBUTION SYSTEMS

In this paper, a model is presented which shows the relationship between country grain storage costs and transport bottlenecks that exist in the harvest period. It is shown that transport bottlenecks limit the amount of grain that can be transported from receival points in the peak receival period. This constraint means that the cost of operating country receival points is high because the turnover of storage capacity is limited. However, system costs can be reduced by focusing the peak transport task at sites that are less intensive users of scare transport capacity. This allows more grain to be transported out of the system in the peak period, decreasing the need for costly long term storage at country sites. In the longer term, differences in the intensity of transport use means that optimal levels of investment in storage capacity (relative to grain receivals) will differ between sites. Relatively more storage should be constructed at sites that are intensive users of transport capacity (eg. those sites that are furthest from the port). Less storage capacity is needed at sites that are less intensive users of transport because a large depot-to-port transport task will be concentrated at these sites in the peak period.