Le monde des transports et de la mobilité requiert une restructuration vu la croissance des échanges. Transférer une partie du trafic de marchandises de la route vers des modes de transports plus respectueux de l'environnement est un élément clé d'une politique de transport durable de marchandises sur des longues distances. Cette étude s'inscrit dans ce cadre en essayant d'évaluer l'opportunité de développer le transport combiné rail-route. Plus précisément, elle propose de localiser de manière judicieuse des terminaux dédiés au transbordement de fret continental, afin de permettre l'expédition de marchandises sur longues distances avec des volumes suffisamment grands pour que le transport combiné soit compétitif. Deux problèmes de localisation sont mis en évidence : le problème du p-hub médian qui répond au critère d'efficacité et le problème p-hub centre qui répond au critère d'équité. La méthodologie présentée, offre un outil de décision s'appuyant sur une modélisation du transport combiné et prend en compte la variation des coûts de transbordement en fonction du nombre de conteneurs transbordés. Elle permet également d'analyser les variations des aires de marché des terminaux en fonction de l'offre et de la demande de transport, ainsi que de mesurer les impacts sur la répartition modales.
There is a growing imbalance between modes of transport in the European Union. The increasing success of road results in an ever worsening congestion, more environmental nuisances and accidents. That's why one of the objectives of the European Common Transport Policy is to restore the balance between modes of transport and to develop intermodality. Among the various types of intermodal transport this doctoral dissertation is concerned by rail-road combined transport for which the terminals are embedded in a hub-and-spoke network. This kind of topology can reduce the transportation costs by consolidations at the hubs. The proposed method uses the flows of commodities and their geographic spreading as input to determine a set of good potential locations for transfer container terminals. This set can further be used as input for an iterative procedure based on both the p-HMP and the multi-modal assignment in order to identify the optimal locations for such terminals in Europe. This procedure takes into account the variation of the transshipment cost according to the number of containers that could be transshipped.
Unmanned Aerial Vehicles (UAVs) may solve, or at least reduce, the negative impacts of road transport such as accidents, pollution and congestion. The objective of this paper is to design UAV networks for biomedical material transportation in line with the Drone4Care project. Political, Economic, Social, Technological, Environmental, Legal (PESTEL) analysis provides an overview of the macro-environmental factors that should be considered. To identify the internal and external factors that are favourable and unfavourable to achieve this objective, Strengths, Weaknesses, Opportunities and Threats (SWOT) analysis is also performed. The raised issues are translated into a number of quantifiable scenario elements containing the most plausible up-coming events that may impact the future of UAV networks. Four location models are developed and applied to the city of Brussels and its periphery with respect to the associated market in terms of biomedical product flows (blood units or medical samples that are transported between hospitals, laboratories, and blood transfusion centres). In the context of separate case studies of scenario-based analysis, the experiments show that the use of charging stations is useful to extend the mission ranges and to gain market share. The results also show the possibility of gradually implementing the bases without requiring any major changes such as closing a base. ; Peer reviewed
External costs have been a key issue in the last years of transport research. In Europe, this trend is in line with the political willingness to internalize externalities in transport pricing policies. This paper has two purposes. It first identifies the recent work achieved in the field of external costs of road and intermodal freight transport, where each paper is assessed in terms of its perspective (academic or project oriented), its objective (prescription, application, projection), the type of externality (air pollution, climate change, noise, accidents, congestion) and the type of cost (marginal, average, total) that is considered. The literature review reveals a gap in the development of generic mathematical functions for external costs of transport. The second objective of the paper is thus to highlight the usefulness of such functions by identifying the main parameters that influence freight transport competitiveness in terms of external costs, and by determining which of these parameters should be incorporated in further research works. ; Peer reviewed
In the current Transport White Paper, the European Union presents a roadmap for a more competitive and sustainable European transport system. Concerning Urban Freight Transport, responsible for about a quarter of CO2 emissions of the transport sector, one of the goals of the EU is to achieve essentially CO2-free city logistics in major urban centres by 2030 by developing and deploying new and sustainable fuels and propulsion systems. The gradual phasing out of 'conventionally-fuelled' vehicles from the urban environment contributes to reduce oil dependence, greenhouse gas emissions and local air and noise pollution. To meet European air quality standards, authorities of some major European cities have already introduced Low Emissions Zones where access to urban areas is limited to freight vehicles that meet certain emissions standards. Greater use of low-emission urban trucks based on electric, hydrogen and hybrid technologies would reduce air emissions, but also noise, letting to use road infrastructure more efficiently by making night deliveries and avoiding morning and afternoon peak periods. In addition to their role in the reduction of polluting emissions, the development of low-emission vehicles also allows to mitigate the dependence of the transportation sector to high fossil fuel prices. Electric vehicles have the potential to be powered by renewable energy sources such as wind and solar energy. However, weaknesses can be found in the limited capacity of the battery and the time needed to recharge, and consequently, the limited driving range of electric vehicle. The main sources for final energy consumption are the vehicle size and the engine characteristics, the load factor, the driving pattern, the gradient which represent the average topology of the country, the speed and the acceleration. To maximize the driving range, a routing model, which aims at minimizing the energy consumption, has to be developed. Our paper focus on the Electric Vehicle Traveling Salesman Problem (EV-TSP): given n cities, find the shortest tour, i.e., the shortest directed cycle containing all cities. The classical objective is to minimize the cost tour scheduling to fulfill delivery requests at each location. In this paper we consider the energy cost and we present an extension of the classical problem to minimize the remaining storage capacity of all electric vehicles at the destination node, knowing that there is no recharge operation on the tour. The objective function accounts not just for the travel distance but also on the load of the vehicle and on its speed while the energy consumption of the engine additionally depends on the path to travel, on the slope of the roads and on the vehicle specifications. Moreover, negative consumption that may happen due to regenerative breaking and kinetic energy capture on downhill paths is taken into consideration. Mathematical model is described and computational experiments are performed. ; Peer reviewed
The growing trade between Europe and the rest of the world and the enlargement of the European Union has led the European Commission's Directorate-General for Energy and Transport to fund Worldnet – Worldwide Cargo Flows – within the Framework 6 research project under the Scientific Support to Policies initiative. The main outputs have been an extended freight origin-destination database for the year 2005, extended road and rail networks, and new maritime and air-cargo networks. Moreover, these outputs were developed according to TRANSTOOLS (Tools for TRansport forecasting ANd Scenario testing) specifications. Due to the magnitude of the project and to the consequences that its results could generate in transportation planning at European level, this study assesses the validity of the freight origin-destination matrix. Our analysis indicates multiple problem cases, inconsistencies and aberrations.
The political pressure in favour of multi- and inter-modal transport has oriented the focus on sustainable transport solutions. Inter-modal transport is one of the possible solutions, but its efficiency strongly depends on the places where the container terminals are located. The number of possible locations on large scale networks becomes rapidly too large to be taken as input by exact location methods. That's why the first goal of this paper is to outline a method that helps to identify the best potential locations out of the thousands of potential nodes. The basic idea is to use the flows of commodities and their geographic spreading as input to determine a set of good potential locations for transfer inter-modal terminals. This set can, in a second step, be used as input for already well known optimal location models in order to identify the optimal locations for container terminals in Europe. The methodology is illustrated over the whole trans-European networks. The paper concludes with a discussion of the results: the model predicts a reduction of the total transportation costs on the network and a modal shift from road to rail. It also evaluates the new modal shift and other indicators
The current and expected growing number of people living and working in cities, as well as the limited space available inside city centres, implies an always greater exchange of inbound and outbound freight flows between city centres and their surrounding regions. Urban freight transports provide economic benefits to society but are also responsible for negative externalities such as congestion, air and water pollution, climate change, accidents and noise. They are more polluting than long-distance freight transports because of the increasing consumption of fuel due to the frequent stops on their delivery route. Moreover, due to traffic congestion, most of the transport vehicles are using alternative routes which are associated with a longer transport time, higher transport costs and negative impact on society and the quality of life. Regulatory measures are rules made by the city or further governmental authorities. Access restrictions are one of the most applied measures to control urban traffics in specific areas of the city. There are several types of access restrictions from time windows, emissions and noise limits to vehicle weight and size. Policy measures can be of various types such as the implementation of low emission zones, the introduction of cleaner vehicles or the encouragement to use non-motorized transport such as bikes. Measures related to land use planning and infrastructure are usually very cost-intensive and thus include long time planning and long implementations periods. These measures range from on-street as well as off-street loading zones to specific delivery zones and collecting points. Also, Urban Consolidation Centers (UCCs), inside and outside the city, are part of these measures related to land use planning. Over the last years, the idea of consolidation of goods has been downscaled; this idea is associated with micro-depots. The objective of this paper is to determine how to efficiently distribute various products made by small and medium firms to customers from different cities. Some of these firms have delivery vehicles. Besides, some delivery companies are available for collecting or picking up goods from different firms. These delivery companies have several vehicles which can carry products to customers or to small depots which can be located in different points in the cities. We will consider the whole \textit{distribution network}, allowing us to make decisions at firm, delivering companies and satellite level. We propose a mixed-integer linear program for the specific case of a multi-echelon multi-product distribution network considering heterogeneous capacitated vehicles. The validity of this model is tested on small-scale instances. To solve problems of a more realistic scale, we develop a matheuristic. Acknowledgements With the support of Wallonie-Bruxelles International. ; Peer reviewed
In this paper, we discuss service network design models for consolidation-based freight transport systems. Two path-based formulations are presented for the domestic and long-corridor cases, respectively. In the context of intermodal transport as a relevant application, the modelling frameworks are applied in Belgium-related case studies, in order to draw meaningful managerial insights. Several future scenarios are experimented by analysing a number of parameters that have been identified as significant operational factors and policy levers. The results underline the costly position of rail transport and a clear economic favouring of inland waterways (IWW), potentially attributed to the high rail fixed costs. Additionally, it is suggested that intermodal transport can benefit from rail subsidies, especially during the early stages of covering the market. Even in the best-case scenario, the resulting modal shares are far from reaching the figures desired for freight transport in the EU. Thus, more powerful instruments need to be implemented to promote greener transport schemes. ; Peer reviewed
The aim of this paper is to consider the topic of pricing decisions in the context of intermodal transport as a subject of significant influence on intermodality's success and the move towards environment friendly modes to bring about a European sustainable transport system. We review the state of research in intermodal pricing from an Operational Research (OR) perspective as a subject with a vital link to energy consumption and sustainability assessment. In particular, we study freight transport within a revenue-maximizing perspective. Driven by the political incentives to enhance its challenged market position, we direct our discussion to the particular gap in optimization approaches that tackle service prices as explicit tactical decisions from the carriers' point of view. A suggestion to utilize the bilevel programming framework in the present context is put forward, as well as an account of its widely successful application to similar hierarchical decision schemes. Different approaches to express the shippers' behaviour—the potential intermodal transport customers—within the lower level problem are proposed, along with the modelling implications of different possible objectives as well as the multimodal network structures. ; Peer reviewed
In the last decades, the market of goods became globalized, increasing international trade relations and the demand for long distance transportation. As a consequence of the larger distances traveled and of the containerization of goods, maritime transportation became more efficient and reliable. In the hinterland, intermodal (rail-road) freight transportation emerged as a competitive alternative to truck-only transportation. In one of its possible meanings, intermodal freight transportation is the multimodal chain of container-transportation services [1] that, e.g., brings containers from (or to) the seaport by barge or rail to (or from) an intermodal terminal in the hinterland from where they are shipped by truck to their final destination (or origin). This study focus on inland intermodal freight transport, in particular, on the rail–truck transport of cargo containers in Belgium. This European country has a long rail system and in the last years has readapted this system in order to handle with containerized cargo. Since 2004, some rail-road terminals have been built and new intermodal services between the seaports of Belgium have been established. In addition, with the aim of promoting the modal share of intermodal rail-road transport, the federal government of Belgium started subsidizing part of the rail transport cost and of the transshipments costs at the rail-road terminals. With these investments the intermodal freight flows in Belgium have increased. ; Peer reviewed
This paper discusses the impact of three freight transport policies aiming to promote railroad intermodal transport in Europe, and examines the case of Belgium as a testing ground. These policies consist in subsidizing intermodal transport operations (such as in Belgium, to stimulate rail transport), internalizing external costs (as recommended by the European Union in order to foster cleaner modes), and adopting a system perspective when optimizing the location of inland intermodal terminals. The study proposes an innovative mixed integer intermodal freight location-allocation model based on hub-location theory and deals with non-linear transport costs in order to replicate economies of distance. Our analysis suggests that subsidizing has a significant impact on the volumes transported by intermodal transport, and, to a lesser extent, that optimizing terminal location increases the competitiveness of intermodal transport. On the other hand, according to our assumptions, internalizing external costs can negatively impact the promotion of intermodality. This finding indicates that innovative last-mile transports are needed in order to reduce the external impacts of drayage operations. ; Peer reviewed
In this article an Iterated Local Search algorithm for the capacitated vehicle routing problem with sequence-based pallet loading and axle weight constraints is presented. Axle weight limits impose a great challenge for transportation companies. Yet, the literature on the incorporation of axle weight constraints in vehicle routing models is very scarce. The effect of introducing axle weight constraints in a CVRP on total routing cost is analyzed. Results show that integrating axle weight constraints does not lead to a large cost increase. However, not including axle weight constraints in the planning process may induce major axle weight violations. ; Funded by the Interuniversity Attraction Poles Programme initiated by the Belgian Science Policy Office (COMEX project: Combinatorial Optimization: Metaheuristics and Exact methods). The computational resources and services used in this work were provided by the VSC (Flemish Supercomputer Center), funded by the Research Foundation - Flanders (FWO) and the Flemish Government - department EWI.
