The effect of the competition between cars and trucks on the evolution of the motorway transport system

Motorways, which were devised at the beginning of their history as dedicated roads intended to be traveled by cars only, are at present also traveled by considerable flows of trucks. This fact has deeply changed the motorway transport system with respect to its original conception, owing to the interactions between two categories of vehicles whose characteristics are very different. These interactions greatly increase the transport cost perceived by car drivers with respect to truck drivers. This paper studies the consequences of this cost asymmetry on the evolution of the transport system when the geometric characteristics of a motorway remain unchanged in time, while transport demand increases. By using a theoretical model of competition between cars and trucks, it is shown that, if both the geometric characteristics of a motorway and the increase rate of the activities that feed the transport demand remain unchanged over time, the competition between cars and trucks, as well as the fact that in general passengers have better transport alternatives than freight, make the increase rate of truck traffic greater than that of cars, causing a progressive increase in the proportion of trucks in the time periods in which a motorway is traveled by both the vehicle categories. Since truck traffic on motorways, at least in Europe, is very scarce on weekends and in holiday periods, in which motorways are traveled almost only by cars, these results seem to indicate a tendency to the specialization of motorways, which are likely to be used in the future mostly by only one category of vehicles in different periods of time.     

Optical device for measuring the injectors opening in common rail systems

Since the needle displacement exerts a fundamental influence on the operation of Common Rail injection systems, accurate measurements of the control piston position can be crucial for a more thorough analysis of the behaviour of injectors, in particular when multiple injections are employed. Eddy current sensors have traditionally been used in lab activities to measure the control piston position inside injectors; apart from the high cost, the scientific literature clearly shows their inadequacy, which is mainly due to the presence of electromagnetic disturbance: the current pulse, which controls the opening of the injector, generates electromagnetic fields which strongly affect the acquisition of data. Many attempts have recently been made either to solve the interference occurring during such measurements or to propose alternative displacement transducers whose operation is not influenced by electromagnetic interference. In this paper, a new device for measuring the injector opening is proposed: it is an optical transducer characterized both by simple and very cheap construction and by a reliable physical principle for measuring the control piston lift. The reliability of the proposed sensor is assessed by a thorough experimental campaign and by comparing the experimental results with the numerical predictions achieved by a Common Rail injector model. Since the assembly of the optical sensor does not affect the injector operation, it can efficiently be used both for experimental tests and for on-board diagnosis and monitoring of the injector operation.     

Sustainability perspectives when crop use is implemented in different sectors: A life cycle assessment approach

The present study aims to provide a preliminary overview of the sustainability concept when biomasses conceived for food goals become the raw materials upon which different sectors, such as plastic or energy industry, can develop innovative strategies, according to a so called ??greener?? competitiveness. In the results hereafter presented, the definition of sustainability perspectives, according to the use of a life cycle assessment (LCA) approach, will be described for maize use as raw material in different sectors. The current biopolymer industry and conventional biofuel technologies, the so called first-generation biofuels, are the more and more in competition with the food sector. The presented environmental evaluation, in terms of air emissions, energy and water consumption, is useful in order to understand the sustainability of a bio-sourced product, in comparison with the equivalent item produced by fossil fuels.     

Home-work carpooling for social mixing

Transportation - Shared mobility is widely recognized for its contribution in reducing carbon footprint, traffic congestion, parking needs and transportation-related costs in urban and suburban...     

Evaluation of alternative scenarios of labour flexibility for dockworkers in maritime container terminals

In the competitive environment of Container Terminals (CTs), it is essential to reduce unproductive costs and to offer efficient services to shipping companies. One of the most important factors for CT efficiency is to plan workforce optimally. However, in some CTs, strict work regulations can avoid an optimal use of the available resources leading to longer operation times and to additional related costs. This study analyses labour regulations in Italian CTs and evaluates the effects of a greater labour flexibility at the operational level by hypothesising an increase of the labour flexibility allowed within the pool of internal dockworkers. The scenario representing the current work organisation in Italian CTs is compared to five new scenarios constructed by increasing the share of daily working flexibility and introducing a new type of labour flexibility, the so-called mini-flexibility. The use of a state-of-the-art Integer Linear Programming Model for the daily assignment of human resources in CTs allows to simulate the quantitative effects of each scenario in terms of operating costs and workers undermanning. Quantitative results support the idea that an increased labour flexibility in CT activities can actually lead to a significant reduction of the operating costs and to a greater efficiency of the CT.     

A comparison of rail liberalisation levels across four European countries

This paper presents the results of a research into railway regulation and liberalisation in Italy, France, Germany and Spain. The analysis covers the relationship between the State and the rail companies, network access conditions by operators, slot allocating and pricing schemes and how public service obligations are defined, financed and regulated.     

A new method for measuring the quality of circulation on motorways

The paper presents a method of measuring the quality of circulation worked out by processing the data derived from 155, 000 vehicle passages over two sections of two-lane, divided-carriageway motorway of identical geometric characteristics. The mass of observed data was broken down into a sequence of 293 periods of constant flow rate, each characterized by a specific flow rate and percentage of heavy vehicles. The percentage of vehicles passing on lane No. 1 and the suitable transformations of the characteristics of the speed and time headway processes on the two lanes during each of the periods gave rise to a vector of 15 components representing the circulation conditions during that period. By performing a linear transformation of the vectors for the 293 constant flow rate periods, it was possible to single out three non-correlated variables, called the “principal components”, which accounted for 75% of the total variance observed for the 15 components, and in turn permitted the representation, without excessive distortion, of the observed circulation conditions within a three-dimensional space by means of a swarm of 293 points. Analyzing the manner in which the three principal components varied jointly within the swarm, a total of four zones were identified, representing respectively free flow, stable flow, unstable flow and forced flow. Moreover, it was possible to identify the numerical value of the quality of circulation with the first principal component, which by itself accounted for 55% of the total variance. This component showed very strong correlation with the flow rate and the percentage of heavy vehicles, and thus permits among other things the mutual comparison of the conditions of circulation caused by different flow rates and compositions.