Planning problems for rail operations

While pipelines are used for (almost) continuous transports of chemicals between and inside chemical production sites, rail transports are (typically) used for smaller and more sporadic shipments between chemical production sites and to customers with rail road access. Rail transports are of special interest in basic chemical industry because large quantities of material can be transported at once on a dense infrastructure compared to waterway or pipeline networks. Particularly locations without access to navigable waterways often depend on this mode of transport. Moreover, travelling times for rail transports are often easier to calculate and uncertainty is smaller in contrast to waterway transports. Hence, rail transports are typically a reliable and well predictable mode of transport. 

However, transport capacities of ships and barges are generally larger than train capacities. Hence, transport cost rates per volume and distance unit are typically higher for rail transports. Since most large-scaled chemical production sites have waterway access, raw materials are typically supphed via ship transports, but intermediate and minor basic chemicals are often transported via rail e.g. because the distribution structure is disperse and/or not all customers/suppliers have waterway access. 

Compared to pipeline and ship, rail transports are more flexible,but require more organizational and technical efforts. Hence, the next subsection sheds light on technical and organizational details considering rail transports of chemical products. Subsequently, an operational planning model is proposed aiming to support short term transport decisions in a chemical production network connected by rail links. 

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