Session 3: Synchromodal Transport – Chair: Rob Zuidwijk
Martijn Mes (University of Twente) – Anticipatory synchromodal transport planning
We study the problem of selecting transport modes and transfers in a synchromodal network over a multi-period horizon. Freights with different characteristics become known gradually over time. Using probabilistic knowledge of freight arrivals, the planner balances current and future costs at each period. We model this Dynamic Service Network Design (DSND) problem as a Markov Decision Process (MDP) and solve it using Approximate Dynamic Programming (ADP). Using different problem settings, we show that our look-ahead approach has significant benefits compared to benchmark heuristics.
Ioanna Kourounioti (Delft University of Technology) – Serious gaming: a method to capture behaviour in freight transport
In Serious Gaming (SG) participants take up a specific role and react in different situations opposed to them by a simulated environment. Specifically, the definition of serious gaming is ‘a conscious endeavour to reproduce the central characteristics of a system in order to understand, experiment with and/or predict the behaviour of that system. SG applications have been used to raise awareness, to introduce innovations and to train employees. On the other hand, discrete choice models have been apply to quantify the factors that influence transport related choices. For model development we use Stated Preference (SP) scenarios. SP approaches may be therefore applied to test the introduction of new policies though the design of realistic scenarios for new policies. However, one of the biggest disadvantages of SP is the hypothetical design of experiments. Sometimes respondents are asked to state their opinions in unfamiliar situations resulting in making choices limited by lack of information or understanding. In addition, SP surveys when combined questions aiming at the collection of socioeconomic and Revealed Preference (RP) data, can be quiet long and time-consuming resulting in low response rates. The possibility to use SG applications as a survey instrument when studying individual behavior is investigated. The games developed to research synchromodality related issues are used as a case study to research the behavior of freight agents.
Alberto Giudici (Erasmus University Rotterdam) – Reliability in synchromodal transport: a bilevel programming planning approach
Import flows of containers face a wealth of uncertainties while being routed through the hinterland of a seaport towards their inland destination: starting from the arrival of ocean liners to the actual release of the containers at terminals, from congestion at the port to miscoordination between operators in the transport chain. All of those uncertainties impact the lead time taken by any operation. Practitioners hedge against uncertainties by adding slack to the duration of their operations and leave slack capacity slots on their transport means to account for last minute change in plans. The introduction of such slacks creates freedom for the update of future flow routing decisions with the aim of maintaining an adequate service level. At the same time, introducing slacks leads to an inefficient use of capacity and assets. Therefore, a trade-off emerges clearly as, on one side, minimal capacity slack would increase the chance of late deliveries of containers as no alternative options are available in case of missed connection and, on the other side, leaving too much slack capacity would be too costly for the operator while containers could be delivered on time. To address this problem, we formulate a combinatorial optimization problem aiming at the minimization of capacity costs, representing the costs generated by slack capacity, and the determination of an optimal strategy for the adaptive routing of a container flow in a stochastic time-varying network guaranteeing a certain service level. In this model, the a-priori decisions on the allocation of capacity to transport demand and the adaptive decision making is taken jointly into account with a punctuality constraint linking the two, the a-priori and the adaptive, time dimensions. In this talk, we are going to introduce the mathematical model and provide the firsts results.