European Transport / Trasporti Europei (2010) 46/XVI

The paper proposes a metamodelling procedure devoted to provide a reference model to be used by decision makers in the performance evaluation of Intermodal Transportation Network (ITN). In order to obtain a generic model describing a nonspecific ITN from the structural and behavioural point of view, the metamodelling approach consists in applying a top down and modular procedure. The model is specified by the well known Unified Modelling Language (UML), a graphic and textual modelling formalism intended to describe systems from structural and dynamics viewpoints. Hence, the paper models a generic ITN starting from the network description and shows by a case study the metamodel of one of the most important nodes that compose it: the port subsystem. Moreover, the case study model is translated in a simulation software and the performance measures obtained by the simulation results are shown.

Urban areas are vital centers of economic activity and innovation generating large economies of density and proximity. Yet, procuring and distributing goods in an urban context is fraught with difficulties because of infrastructure congestion, external costs, conflicting objectives among stakeholders, and asymmetric information. In order to improve the performance of the urban goods transport system many policies have been proposed, including goods vehicle time windows, vehicle-type restrictions, loading\unloading policies, fiscal policies, the promotion urban transhipment and consolidation centres. Unfortunately, not much is known concerning how these policies affect the existing distribution practices. It is quite likely that the impact is differentiated by type of product and distribution channel. The aim of this paper is to explore this issue. Drawing on the existing literature and on the empirical evidence from some Italian cities, the paper identifies and discusses the relationship between each of the above-mentioned policies and the distribution channels of some goods (fresh food sold in retail stores, food distributed by Hotels, Restaurants and Catering (Ho.Re.Ca.), pharmaceutical products and clothing&footwear) which are commonly distributed in Italian urban centers. It is found that the distribution of pharmaceutical products is unaffected by these policies, whereas the distribution of fresh food is negatively affected especially by access time regulation and loading\unloading policies. The Ho.Re.Ca. and the clothing&footwear channels are likely to be impacted the most by fiscal policies and by the promotion of urban transhipment and consolidation centres.

This paper presents a macro-architecture for simulating goods movements in an urban area. Urban goods supply is analysed when the retailer is the decision-maker and chooses to supply his/her shop. Two components are considered: demand in terms of goods supply and vehicle routing with constraints to simulate goods movements. To analyse demand we consider a multi-step model, while to analyse goods movements a Vehicle Routing Problem with Time Windows (VRPTW) is formalized. We examine the distribution process for a VRPTW in which the optimum paths between all the customers are combined to determine the best vehicle trip chain. As regard optimum path search, a multipath approach is proposed that entails the generation of more than one path between two delivery points. Some procedures (traffic assignment, real time system measurement, reverse assignment) to estimate system performance are also proposed. Finally, heuristics to solve the proposed problem are reported and their results are compared with those exact.

A freight terminal is a key node in a transportation network and the transit time of containers through this terminal represents one of the most relevant bottleneck in logistic chains. The system performance reduction and the corresponding increase of transit time is often due to the increase of the freight flow without a corresponding increase of stacking and handling capacity. For this purpose it was decided to approach the problem by a discrete event simulation model, in order to reproduce the activities carried out inside an intermodal terminal, to calculate the total transit time and to identify the bottlenecks. The transit time of a cargo unit in a terminal is the summation of times required for the development of each phase of the process (waiting time + operational time). Therefore, the first step was the identification of the main activities and the analysis of waiting and operational phases, in order to quantify the times of each phase. For modelling the software Planimate® was used. Planimate® allows the simulation of a process as a set of discrete events, in series or in parallel, through the use of hierarchical networks. In order to optimise handling operations on containers, different scenarios were simulated with various fleets of trailers and front cranes to investigate the corresponding variations of performance indicators. For the application of the model an Italian case study was chosen: the container terminal inside the harbour of Livorno (Darsena Toscana Terminal).

In city logistics, service providers have to consider dynamics within logistics processes in order to achieve higher schedule reliability and delivery flexibility. To this end, city logistics routing demands for time-dependent travel time estimates and time-dependent optimization models. We consider the process of allocation and application of empirical traffic data for time-dependent vehicle routing in city logistics with respect to its usage. Telematics based traffic data collection and the conversion from raw empirical traffic data into information models are discussed. A city logistics scenario points out the applicability of the information models provided, which are based on huge amounts of real traffic data (FCD). Thus, the benefits of time-dependent planning in contrast to common static planning methods can be demonstrated.

This paper analyses three different approaches of supply representation for intermodal nodes and proposes some functional and topological models for the representation of ports and Freight Villages. Besides in the paper functional and topological representation of container port and freight village are proposed. Further research is directed to the specification and calibration of cost functions, useful for cost estimation for different components of node network, with a view to facilitate the analyses of freight mobility on multimodal large networks.

The aim of this paper is to find an optimal solution to operational planning of freight transportation in an industrial district. We propose a system architecture that drives agents – the industrial district firms - to cooperate in logistic field, to minimize transport and environmental costs. The idea is to achieve logistics optimization setting up a community made of district enterprises, preserving a satisfactory level of system efficiency and fairness. We address the situation in which a virtual coordinator helps the agents to reach an agreement. The objectives are: maximizing customers satisfaction, and minimizing the number of trucks needed. A fuzzy clustering (FCM), two Fuzzy Inference System (FIS) combined with a Genetic Algorithm (GA), and a greedy algorithm are thus proposed to achieve these objectives, and eventually an algorithm to solve the Travelling Salesman Problem is also used. The proposed framework can be used to provide real time solutions to logistics management problems, and negative environmental impacts.

Although the technical literature contains numerous efforts to simulate container terminal performance, little attention has been paid to setting up, calibrating and validating models for handling equipment activities. This paper presents results from the estimation of activity duration concerning three different types of handling equipment: mobile harbor cranes, gantry cranes and reach stackers. Two estimation approaches (sample means vs random variables) were investigated with respect to different hypotheses with regard to activity aggregation and container type (undifferentiated, 20’, 40’, full or empty). A concise but exhaustive state of art is proposed, an in-depth descriptive analysis of experimental data is carried out, several probability distribution functions were tested and more than 60 statistical models are proposed. The results can be easily implemented in any terminal simulation model.