An extended TAPAS-Z model and a case study of the transport of forest products

We contribute an extension of the agent-based freight transport analysis model TAPAS-Z, whose aim is to simulate decision- making and other activities in transport chains. TAPAS-Z is a further development of the TAPAS model, and it enables stochastic variation, based on statistical distributions, of the locations of senders and receivers of freight, hence providing improved support for simulation of transport between larger regions. The model extension presented in this paper enables stochastic sampling of sender and receiver locations from historically known data, which we argue is beneficial in those situations where such data exist. We also contribute a case study where we used our extended TAPAS-Z model to simulate transport of timber from forest felling places to a Swedish paper mill. The case study illustrates how we recommend conducting a case study using the extended TAPAS-Z model. The aim of the study was to assess the possible implications of a structural change from a time-based to a distance-based Eurovignette system for heavy freight trucks in Sweden, which will lead to increased costs for most road users. As a mitigation action for the increased costs, we studied the possibility to use heavier trucks than the currently allowed 60 tonne trucks. The simulation results suggest that an introduction of a distance-based Eurovignette is expected to cause a small modal shift from road to rail for the studied type of transport. Furthermore, an introduction of larger freight trucks is expected to lead to a complete shift to road transport.