1,720,997 research outputs found
Preliminary methodologies for selecting diesel railways to be converted to hydrogen
No full textAlthough rail transport is often considered a crucial component of sustainable mobility, in some cases, such as non-electrified railway lines using diesel trains, it may not be entirely sustainable. The ideal solution would be to electrify these lines, but low demand and/or low traffic do not justify the costs relating to the installation of the contact line, the construction of electrical substations and the complete replacement of the train fleet. In this context, the conversion of non-electrified lines from diesel to hydrogen could be a suitable compromise. Indeed, in this context, the Italian National Recovery and Resilience Plan includes investment in hydrogen experimentation on railways and requires the identification of lines to be converted to hydrogen. Hence, this paper proposes some methodologies for identifying the lines suitable for conversion
A methodology based on the depot selection to identify the non-electrified railway lines to be converted to hydrogen propulsion
No full textRail and metro systems are essential for sustainable mobility, offering higher passenger capacity with the same energy consumption and lower emissions compared to cars and buses.
Railway propulsion currently relies on two main technologies: electric and diesel-powered systems. Electric trains produce no local emissions, though their overall environmental impact depends on the energy mix used for electricity generation. Diesel-powered trains use an internal combustion engine to generate electricity and drive the wheels via an electric motor, resulting in emissions directly linked to diesel combustion. The lack of electrification is often due to an unfavourable cost-benefit analysis, as secondary lines often have insufficient traffic to justify the investment.
In this context, to enhance the sustainability of non-electrified railway lines, Italy’s National Recovery and Resilience Plan has allocated €300 million to test hydrogen-powered trains, selecting six lines and nine refuelling stations for conversion. Indeed, hydrogen may serve as an intermediate solution to full electrification, enabling a gradual transition from diesel with minimal infrastructure modifications.
This paper presents a methodology for grouping railway lines that share refuelling stations to optimise hydrogen production, storage, and distribution costs. The approach is applied to the Italian railway network to evaluate feasibility and support the National Recovery and Resilience Plan objectives
A simple railway traction simulator for comparing performances of metropolitan railway vehicles
No full textThe design of additional public transport services to increase the resilience of road networks
No full textSome events (as, for instance, a bridge collapse, an underpass closure or a road maintenance intervention) may generate the total or partial unavailability of some elements of urban road networks. Hence, some users have to redirect their paths generating an increase in congestion on the remaining part of the network. In this context, this paper proposes the design of additional public transport services to increase the resilience of road urban networks by affecting the user modal choices to reduce road flows and bring congestion levels as close as possible to the initial equilibrium conditions. Finally, to verify the usefulness and feasibility of the proposed methodology, it has been applied in the case of the road network of Fuorigrotta, a district of the city of Naples, in southern Italy
Adoption of hydrogen in railway traction: Opportunities and limits in the case of non-electrified railway lines
No full textAlthough rail transport is generally considered a sustainable transport system, and numerous research and design methods are based on considering rail transport as the backbone of public transport and/or sustainable mobility, it is necessary to highlight that in some cases railway lines are still based on the use of diesel-powered trains, since these railway lines are still non-electrified. Indeed, for instance, in Italy, compared to approximately 25,000 km of railway network, almost 19% consists of non-electrified railway lines. Moreover, the Italian National Recovery and Resilience Plan (included in the European Next Generation EU Programme) provides for the allocation of about €300M for the testing of hydrogen in rail transport. In this context, the objective of this paper is to provide an analysis of the opportunities and limits associated with the use of hydrogen-powered trains on non-electrified railway lines
The influence of passenger weight on rail and metro running times: Theoretical formulation and applications to the case of Line 1 of the Naples metro system (Italy)
No full textAnalyses of transport systems require knowledge of the interactions between travel demand and transport system performance. In general, the travel demand depends on transport system performance, and in turn the transport system performance depends on how many users use the same element at the same time.
In the literature, rail and metro systems are generally considered uncongested (i.e. performance does not depend on the travel demand) at least as regards train running times.
This contribution examines the dependence of train running times on the number of transported users. Indeed, in rail and metro contexts, the weight of carried passengers in the case of a full load has the same order of magnitude as the unloaded train weight. Hence, variation in the maximum traction effort and the motion resistance between a fully loaded and a completely empty condition implies variations in train running times. Moreover, in frequency services, even in the case of constant demand (i.e. rigid demand assumption), the number of users boarding each train depends on the service frequency. Hence, since service frequency depends on the running times through the cycle time, it is possible to identify a fixed-point problem between the number of boarding passengers and train running times.
The application to the case of Line 1 of the Naples metro system has shown the extent of these variations and the extension times conditions that allow defining a cycle time independent of demand variability
Renewal of rolling stock in a metro line: performance analysis and operational implications
No full textIn modern cities characterised by high population density, the mobility problem can be addressed by utilizing efficient public transportation systems. Shifting the demand from private cars to these systems can both increase the livability of a place and reduce negative environmental impacts. In this perspective, vehicles for urban rail and metro services should be periodically updated to meet the demand and replace obsolete rolling stock. However, the new rolling stock could have different performances compared to the old one and, in the case of such significant modernisation, an evaluation of the differences in performance between the old and the new configuration is necessary. Indeed, the modifications can bring benefits or disadvantages from a user or company cost perspective. In this work, a model is presented to compare the total cost, considering both energy costs and passenger travel costs, in the event of an update of the rolling stock. The model is then applied to Linea 1 of the Naples metro system (Italy) to evaluate the feasibility and usefulness of this approach
Effects of the passenger weight on the train running times and related implications on service frequencies
No full textAlthough rail and metro systems are traditionally assumed to operate without congestion (i.e., transportation system performance is not influenced by travel demand), this study investigates how passenger volume affects train running times. Indeed, the passenger number significantly alters train dynamics, particularly when trains are fully loaded, and boarding passenger number depends on service frequency, creating a fixed-point problem between boarding passengers and train running times. An analysis of Line 1 of the Naples (Italy) metro system demonstrates these variations and highlights criteria for establishing a cycle time that remains stable despite fluctuations in demand
Service frequency variability and its dependence on the passenger number and fleet composition
No full textRail and metro systems are generally considered uncongested, as variations in running times between stations are negligible compared to other systems, such as road transport, where congestion can increase travel times more than three times compared to normal conditions. This study analyses the effects of variability in the number of passengers on rail and metro vehicles (and related variation in total train weight) on running times. Indeed, although the variations in running times are neglectable, they can compromise the stability of service frequency, triggering mechanisms that lead to a deterioration of system performance. Therefore, the paper proposes a methodology for analysis to assess whether such variability could influence the stability of service frequency. An application to Line 1 of Naples metro systems, in Italy, has shown that in ordinary conditions the layover time is able to absorb any running time variations thus ensuring the stability of the service frequency
Quattro Quartieri. Spazio urbano e spazio umano nella trasformazione dell’abitare pubblico a Roma
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