The railway freight terminals play a key role within the multimodal logistic chain. Therefore, the transit time through these terminals represents one of the most relevant terminal performances and at the same time a key component of the freight transport generalised cost, so that its quantitative analysis is a strategic activity, both in the terminal planning and in the logistic chain organisation. The transit time is composed by deterministic and stochastic components, which increase significantly the problem complexity. The considered freight terminals are: land freight interchanges (interchange between trains and trucks); marshalling yards (modification of the composition of trains within the railway system); and railway maritime terminals (interchange between ship and trains). The model finalised to the determination of the transit time has been structured on the basis of its following general and, nevertheless, simple formalisation: TTR = TE (C, O) + TI (T, D, R) where: TE depends upon external infrastructures and transport services formalised in two arrays including parameters and constraints; carrying capacity C (e.g. railway line bottlenecks, etc.); operation planning O (e.g. timetable structures of the transport services arriving at the terminal and departing from it, etc.); TI depends upon technologies, dimensions and operational rules in the terminal formalised in three arrays including parameters and constraints. These are: terminal planning parameters T (e.g. check-in and transfer technology); terminal dimensions D (e.g. distances between gates and transfer area, number of tracks, etc.); and operational constraints and rules R (e.g. speed limits, maximum loading weights, etc.). The model is characterised by wide generality and applicability to different terminal typologies, lay-outs, dimensions and transfer technologies. This approach highlights contributions and weights of the various activities and phases of the freight unit transit through the terminal by distinguishing operational and waiting periods, whose duration depends not only upon internal performances (technologies, dimensions and operational rules) but also upon external parameters and constraints (time distribution of vehicles arrivals and departures). Actually, the results of some case studies showed that the amount of time dedicated to the activities only depending upon internal parameters is generally very limited (about 5% in the land freight interchange case studies). For the covering abstract see ITRD E126595.
Samenvatting