Abstract:
The South African inland logistic systems are heavily reliant on existing road networks. The bulk
transportation of goods, such as coal, increases the loads the roads currently have to carry and lead
to damaged roads that in turn increase logistic costs. For these and other socio-economic reasons
the strategic decision has been made by one of the major coal transportation companies in South
Africa to migrate the transportation of coal as far as possible from road to rail. To support this
strategy, coal consolidation centres are to be optimally located, whereby road-based coal will be
diverted to the hubs and transported by rail to the demand point.
The purpose of this project is to develop and evaluate mathematical models that could be used
by decision makers to determine optimal locations of coal consolidation centres. To ful ll this
aim two mathematical models are developed: a network-based model in which a limited number of
prede ned nodes along the existing rail network can be chosen as hub locations, and the continuous
model in which all points on the plane are considered. The two main objectives are to decrease
total operational cost and to migrate the transportation as far as possible o road and onto rail.
A test case is used to highlight strengths, weaknesses and underlying behaviours of the models.
The most noteworthy endings involve the major weaknesses of both models. The greatest weakness
experienced by the network-based model is the limitation of the possible hub locations; improved
locations not on the rail network are excluded and could yield improved results. The continuous
model eliminates this weakness, however, it does not consider the distance along the rail network in
calculating optimal locations. This chosen locations the continuous model yields are numerically
inferior to the network-based counterparts. For these reasons the decision is taken to use both
models in order to achieve optimal results; the continuous model is used to determine additional
hub locations, while the network-based model is used to determine nal results.
In the procedure described above, mathematical models are developed with the capability to
guide decision makers in determining optimal coal consolidation centres. The results with regard
to the case study are analysed to give recommendations to guide the decision-making process.
