Substitution and complementarity patterns between traditional transport means and car sharing: a person and trip level analysis

Transportation - Car sharing is a new transport mode which combines characteristics of private and collective traditional transport means. Understanding the relationship of this mode with existing...     

An artificial neural network based method to uncover the value-of-travel-time distribution

Transportation - This study proposes a novel Artificial Neural Network (ANN) based method to derive the Value-of-Travel-Time (VTT) distribution. The strength of this method is that it is possible...     

Waiting profiles: An efficient protocol for enabling distributed planning of container barge rotations along terminals in the port of Rotterdam

We consider the problem of aligning barge rotations with quay schedules of terminals in the port of Rotterdam. Every time a barge visits the port, it has to make a rotation along, on average, eight terminals to load and unload containers. A central solution, e.g., a trusted party that coordinates the activities of all barges and terminals, is not feasible for several reasons. We propose a multi-agent based approach of the problem, since a multi-agent system can mirror to a large extent the way the business network is currently organized and can provide a solution that is acceptable to each of the parties involved. We examine the value of exchanging different levels of information and evaluate the performance by means of simulation. We compare the results with an off-line scheduling algorithm. The results indicate that, in spite of the limited information available, our distributed approach performs quite well when compared to the central approach. In addition, our experiments indicate that an information exchange based on waiting profiles reduces the average tardiness per barge with almost 80% when compared to the situation with no information exchange. We therefore think that waiting profiles provide a promising protocol to tackle this problem.     

A medium-resolution wave hindcast study over the Central and Western Mediterranean Sea

The present study is aimed at determining the confidence limits of design wave parameters derived from numerical modeling—for both extremes and operational conditions—over the Central and Western Mediterranean Sea. The paper presents the methodology and results of an extensive validation activity conducted on a chain of medium-resolution third-generation wave models used for hindcast purposes. The stringent requirements of state-of-the-art coastal and offshore engineering applications over this area make the adoption of medium- or high-resolution hindcast wave and wind models almost mandatory because of the complex coastal geometry, bathymetry, and orography that in turn lead to large variations of the design wave parameters even within small regions. The chains of nested meteorological and wave models used in this hindcast study belong to the ETA and WaveWatch III families, respectively. In this study the wind and wave numerical models have been run over the past 20 years, with increasing resolutions of the wave models from 0.2° up to 0.04°. The results presented herein have 0.1° resolution for both wind and wave models. The wave data obtained are compared with available measurements from 14 wave buoys in coastal zones in the Central and Western Mediterranean Sea.     

The impact of the new onboard technologies on maritime education and training schemes in Europe: some findings from the 'METHAR' project

The paper reports some analyses put forward in the context of the METHAR Project. The purpose is the evaluation of the impact of the new technologies used onboard ships on the Maritime Education and Training systems in Europe and the identification of the future training needs. This issue is tackled by developing an ad-hoc methodology based upon the analysis of the responses to questionnaires sent to a number of operators involved in the maritime sector all over Europe, specifically ship owners, marine equipment manufacturers, pilots and port managers. Results enable the identification of some types of impacts that are named ‘organizational’ and ‘operational’. Moreover, a general evaluation scheme was developed as a tool for highlighting the structure and the characteristics of the impacts considered.     

Social marginal cost pricing and second best alternatives in partnerships for transport infrastructures

According to the economic theory, if all the first-best conditions are met, social optimality involves the prices to be set equal to social marginal costs. When it is not possible to set prices equal to social marginal costs, due to the presence of constraints within the transport sector or distortions elsewhere in the economy, the theory suggests corrections to the SMC principle (second-best alternatives). But the implementation of second best alternatives can give rise to serious problems when transferred from theory to practice. This chapter will discuss in particular the problems that might rise when investment cost are included (totally or partially) in the social marginal costs rules, and in particular when private operators are involved.     

Evaluation of green wave policy in real-time railway traffic management

In order to face the expected growth of transport demand in the next years, several new traffic control policies have been proposed and analyzed both to generate timetables and to effectively manage the traffic in real-time. In this paper, a detailed optimization model is used to analyze one such policy, called green wave, which consists in letting trains wait at the stations to avoid speed profile modifications in open corridors. Such policy is expected to be especially effective when the corridors are the bottleneck of the network. However, there is a lack of quantitative studies on the real-time effects of using this policy. To this end, this work shows a comparison of the delays obtained when trains are allowed or not to change their speed profile in open corridors. An extensive computational study is described for two practical dispatching areas of the Dutch railway network.     

Integrated Agent-based and System Dynamics Modelling for Simulation of Sustainable Mobility

In this article, a conceptual framework for a comprehensive evaluation of the diffusion process of alternative fuel vehicles is introduced. The framework takes into account the most influencing stakeholders, including car manufacturers, car dealers, consumers, energy supply system, fuel stations and government. The underlying mathematical models of different stakeholders are then integrated in one model of the whole energy and transport system. The hybrid modelling framework links the two powerful dynamic simulation approaches of system dynamics (SD) and agent-based (AB) modelling. Integrated modelling structure gives the potential of building more accurate and computationally efficient models for simulating the transition to sustainable mobility. We specify the integration process and the most important linking variables between various energy and transport components. Then the application of the integrated model is explained through a test case and, finally, the applicability of the hybrid AB and SD approach and its potential contribution to the models of transition to sustainable mobility will be concluded.     

Network economies in liner shipping: the role of home markets

This paper deals with the measurement of the network complexity of some selected shipping groups, also identifying the contribution of co-operative agreements among carriers. The empirical investigation is focused on: (i) the analysis of the distribution of the carrying capacity per range; and (ii) the comparison of that capacity with the throughput handled in the port facilities of the group. These variables are interpreted in the light of the impact that alliances have on the geographical wideness of the services supplied by each partner. This factor also allows to depict how the cultural and political origin of shipping lines affects the decision of joining an alliance and the outcomes deriving from such co-operation.