Literatura científica selecionada sobre o tema "Air-Rail substitution"

This paper presents an overview of the environmental performance of high-speed rail (HSR) and air passenger transport (APT) in the European Union (EU). This performance embraces the direct environmental burdens/emissions such as energy consumption, air pollution, noise, land-take and land use, safety and congestion. A comparison of the marginal values of particular burdens/emissions and their costs (externalities) is carried out. The results have shown that significant mitigation of the impacts and savings of costs could be achieved by substitution of air passenger transport by high-speed rail. The substitution can be carried out through competition and complementarity of operations of both modes.

In this paper we present the results of a study that aims to establish the potential for high-speed train travel as a substitute for short distance air travel at Amsterdam Airport. We investigated the 13 most important destinations that offer direct flights to and from Amsterdam Airport. Almost 40% of the air passengers travelling to/from these destinations are transfer passengers. Empirical evidence reveals that high-speed trains dominate the market for journeys of 2 hours or less, such as between Paris and Brussels. However, trains claim only a tiny market share of journeys longer than 5 to 6 hours; air travel dominates that market segment. Using these findings, we developed a model to estimate the substitution of air travel with high-speed train travel. The explanatory variables in this model are travel time, daily departure options, fares, and the inconvenience associated with transferring at airports. In a “minimum” scenario, we predict that in 2030 high-speed trains could replace approximately 1.9 million air journeys. This calculation is based on feasible reductions of train travel times and increased train frequencies for part of the rail network. In this scenario, Amsterdam–London accounts for more than three-quarters of the predicted substitution. In a “maximum” scenario, substitution could increase up to 3.7 million air journeys per year, provided that inconveniences for passengers when transferring at airports from plane to train are resolved and train ticket fares are reduced by 20%. These two scenarios imply a reduction of 2.5 to 5% of all flights to/from Amsterdam Airport in 2030.

Public transport has become a challenge to supply on one side and to afford it on the other side. There are several issues in practical life, which can be associated with the demand for rail transport service, required for sustaining a normal life. This study is based on estimating the determinants of rail transport demand and calculating income and price elasticities for different classes of train services in the short run. The study found that the substitution is dominant and that the own-price effect and income effect are dominant in all the effects. There is a positive relationship between income increase and demand for rail service for air-condition class passengers. The study found that substitute elasticities are positive for rail services, which indicates that rail tracks and buses are substitutes for each other. It entails that rail fares income and road density are constraining variables such that the change in these would consequently bring a change in rail passengers in each class, and fuel price is also significantly reallocating the passenger across each class while the opposite does not hold. The increase in road accidents increases the demand for rail services in Pakistan. Keywords: Demand elasticities, Rail services, Short run, ARDL, and Road Accidents

Research about service operation costs in the rail sector has usually focused on freight, high-speed, or national passenger rail, but has seldom included the study of the cost of urban rail (metro) rapid transit. This study analyzed the determinants of train service costs for a panel of 24 metro systems worldwide. The study used econometric modeling to assess the relative weight of each factor. Wages and electricity prices and consumption were found to have statistically significant elasticities and evidence of potential substitution effects between factors. Other factors, such as driver productivity, network length, percentage of rolling stock with air conditioning, and rolling stock age, also showed statistically significant elasticities. The study found evidence of strong returns to density and returns to scale in the provision of train service outputs (for example, car kilometers, passenger journeys, and train hours).

Multiphysics problems represent an open issue in numerical modeling. Electromagnetic launchers represent typical examples that require a strongly coupled magnetoquasistatic and mechanical approach. This is mainly due to the high velocities which make comparable the electrical and the mechanical response times. The analysis of interacting devices (e.g., a rail launcher and its feeding generator) adds further complexity, since in this context the substitution of one device with an electric circuit does not guarantee the accuracy of the analysis. A simultaneous full 3D electromechanical analysis of the interacting devices is often required. In this paper a numerical 3D analysis of a full launch system, composed by an air-core compulsator which feeds an electromagnetic rail launcher, is presented. The analysis has been performed by using a dedicated, in-house developed research code, named “EN4EM” (Equivalent Network for Electromagnetic Modeling). This code is able to take into account all the relevant electromechanical quantities and phenomena (i.e., eddy currents, velocity skin effect, sliding contacts) in both the devices. A weakly coupled analysis, based on the use of a zero-dimensional model of the launcher (i.e., a single loop electrical equivalent circuit), has been also performed. Its results, compared with those by the simultaneous 3D analysis of interacting devices, show an over-estimate of about 10–15% of the muzzle speed of the armature.

Air transport has been constantly growing and forecasts seem to confirm the trend; the resulting environmental impact is relevant, both at local and at global scale. In this paper, data from various datasets have been integrated to assess the environmental impact of modal substitution with high speed rail. Six intra-EU28 routes and a domestic route have been defined for comparison. The airports have been chosen considering the share of the total number of passengers on flights to/from other EU Member States. Three scenarios have been proposed in the time period 2017–2025; aircraft types, distance bands, and occupancy rate are investigated on each scenario. The comparison with HSR service has been carried out only on passenger service and not for freight. The energy consumption and the consequent emissions for the aircraft have been estimated on the base of the available data for the mix of aircraft types, performing the routes. The results indicate the advantage of the high speed trains, in terms of direct CO2eq emissions per passenger km. Compared to a neutral scenario, with an annual passenger increment of 3.5%, the HSR substitution of the 5% and the 25% of this increment allow a GHG saving of 4% and 20%, respectively. Some of the analysed routes (e.g., Frankfurt Main–Paris CDG) have interesting GHG savings but the duration of the trip today is limiting for a real substitution. Moreover, there is general agreement that the extreme weather events induced by climate change will affect the functioning of the European transport system. In this sense, transportation by the rail mode is expected to play a significant role in strengthening the EU transport system, its resilience, and its reliability, as it is less immediately subject to the impacts of severe weather conditions.

This paper examines the beneficial impact of high-speed rail (HSR) on reducing aviation CO2 emissions in China. As a fast-growing economy and the world’s largest CO2 emitter, China has made massive infrastructure investments but has also committed to reducing emissions across all sectors. This study demonstrates that investments in China’s HSR can effectively contribute to reduction of emissions from domestic aviation, a sector that is particularly challenging to decarbonize. Although a wide body of literature has assessed the competition between HSR and air transport, little attention has been paid to the climate implications of this phenomenon. It is estimated that, through mode substitution for air transport, HSR generated a cumulative net saving of between 1.76 and 2.76 million tons of CO2 from 2012 to 2015. This was equivalent to 3.2%–5.1% of 2015 domestic aviation emissions. Importantly, it is also demonstrated that by not taking into account the electricity consumption of HSR, its environmental benefits could be overestimated. Lastly, through analysis of future energy mix scenarios this study highlights that HSR has a great potential to reduce CO2 emissions even further if China achieved its climate pledge in the Paris Agreement in terms of decarbonizing its electricity generation sector by 2030.

Cette thèse examine des outils économiques et comportementaux pour réduire les émissions de CO2 du transport aérien. Elle est structurée en trois chapitres, chacun traitant d’un aspect spécifique : l’impact des taxes sur les billets d’avion, l’effet du cadrage des émissions de CO2 et l’influence des signaux sociaux sur les choix entre l’avion et le train. Le premier chapitre analyse l’effet des taxes passager sur les billets d’avion en Europe entre 2001 et 2019, tout en prenant en compte l’impact des lignes à grande vitesse (LGV). En utilisant une méthode de doubles différences appliquée aux routes aériennes entre villes, l’étude estime l’effet de ces taxes sur le trafic aérien. Les résultats montrent qu’une augmentation d’un euro des taxes entraîne une baisse de 1 % du trafic aérien, tandis que chaque kilomètre de LGV réduit le trafic aérien concurrent de 0,24 %. Sur la période étudiée, les taxes passager ont permis une réduction de 3 % des émissions de CO2 liées à l’aviation, tandis que les LGV ont contribué à une réduction de 0,4 %. Cette analyse met en lumière l’effet combiné des taxes et des investissements dans les infrastructures ferroviaires pour réduire les émissions du trafic aérien. Le deuxième chapitre explore comment un cadrage des émissions de CO2 peut encourager informations environnementales peuvent orienter les comportements vers des choix moins émetteurs. Le troisième chapitre étudie l’impact de deux incitations : une information descriptive sur les émissions de CO2 des avions et un signal social sur la part d’utilisateurs du train par rapport à l’avion. Une expérience de choix discrets permet d’analyser comment ces outils influencent le choix entre avion et train. Le signal social avec une part modale élevée d’utilisateurs de train a un impact significatif, équivalant à une réduction de 20 % du prix du train. L’information sur les émissions de CO2 a un effet équivalant à une réduction de 5 % du prix du train. Combinés, ces signaux montrent un effet global supérieur à leurs impacts individuels. Ce travail souligne l’efficacité des signaux sociaux dans l’orientation des comportements de transport. Il offre des implications concrètes pour les politiques publiques, suggérant l’utilisation conjointe d’incitations pour maximiser leur efficacité sans effet d’éviction. Cette thèse fournit donc des preuves empiriques sur l’impact des politiques de réduction des émissions de CO2 pour le secteur du transport aérien. Elle montre que les taxes passager, les investissements dans les infrastructures ferroviaires, le cadrage en perte des informations sur les émissions de CO2 et les signaux sociaux peuvent contribuer à des changements comportementaux significatifs, offrant des pistes pour des interventions politiques efficaces combinant des instruments complémentaires
This thesis examines economic and behavioral tools to reduce CO2 emissions from air transport. It is structured into three chapters, each addressing a specific aspect: the impact of taxes on airline tickets, the effect of framing CO2 emissions, and the influence of social signals on the choice between air and rail travel. The first chapter analyzes the effect of passenger taxes on airline tickets in Europe between 2001 and 2019, while accounting for the impact of high-speed rail (HSR). Using a difference-in-differences method applied to air routes between cities, the study estimates the effect of these taxes on air traffic. The results show that a one-euro increase in taxes leads to a 1% decrease in air traffic, while each kilometer of HSR reduces competing air traffic by 0.24%. Over the studied period, passenger taxes contributed to a 3% reduction in aviation-related CO2 emissions, while HSR contributed to a 0.4% reduction. This analysis highlights the combined effect of taxes and investments in rail infrastructure in reducing air traffic emissions. The second chapter explores how framing CO2 emissions can encourage more environmentally friendly transportation choices. A discrete choice experiment evaluates whether a gain-framed message (highlighting the positive impact of reducing emissions) or a loss framed information can steer behaviors toward lower-emissionchoices. The third chapter examines the impact of two incentives: descriptive information on the CO2 emissions of airplanes and a social signal regarding the share of train users compared to air travel. A discrete choice experiment analyzes how these tools influence the choice between flying and taking the train. The social signal, showing a high modal share of train users, has a significant impact, equivalent to a 20% reduction in the price of train tickets. Information on CO2 emissions has an effect equivalent to a 5% price reduction. When combined, these signals show a greater overall effect than their individual impacts. This work underlines the effectiveness of social signals in guiding transport behaviors. It offers concrete policy implications, suggesting the combined use of incentives to maximize their effectiveness without diminishing returns. Thus, this thesis provides empirical evidence on the impact of CO2 emission reduction policies in the air transport sector. It demonstrates that passenger taxes, investments in rail infrastructure, loss-framed information on CO2 emissions, and social signals can contribute to significant behavioral changes, offering insights for effective policy interventions that combine complementary instruments

Studies have shown that short-haul airline passenger traffic (less than 500 miles) is decreasing nationwide. This decline may be attributed to legacy airlines' rising costs (especially fuel), increased airport congestion, and increased travel time due to post-September 2001 TSA security screening. Previous studies tended to look at the substitution of high-speed rail and other transportation modes for air travel, especially as travel times shorten. Substitution usually takes the form of collaboration or competition between competing modes and competing carriers. This chapter presents an alternative view – with a discussion of the proposition that air carriers may benefit more from collaborative arrangements that allow them to “own” at least a portion of the intermodal passenger experience rather than shifting or transferring passengers to competing non-air modes. As we believe that this proposal has merit and is worth consideration, we conclude the chapter with a research agenda designed to empirically test the proposition.

Interest is growing in using fully flexible diesel-gas dual fuel engines for power generation and propulsion on land and sea. Benefits such as the flexibility to adapt the type of fuel to the market situation, fail-safe operation and lower NOx emissions than diesel engines are convincing arguments for engine operators. However, diesel-gas engine concepts still suffer from lower efficiency than state-of-the-art monovalent diesel engines and spark ignited gas engines when operated in the corresponding fuel mode. To meet stringent NOx emission legislation, high diesel substitution rates are necessary, which in turn often lead to poor combustion stability. Especially with these small diesel fractions, the challenge remains to ensure stable ignition, fast combustion of the air-fuel mixture and low hydrocarbon emissions. The aim of this paper is to identify and investigate the potential and limitations of diesel-gas combustion concepts for high speed large engines operated in gas mode with very small amounts of pilot fuel (< 5 % diesel fraction1). Experimental tests were carried out on a flexible single cylinder research engine (swept volume approximately 6 1) equipped with a common rail system. Various engine configurations and operating parameters were varied and the effects on the combustion process were analyzed. The results presented in this paper include a comparison of the performance of the investigated dual fuel concept to those of a state-of-the-art monovalent gas engine and a state-of-the-art monovalent diesel engine. Evaluation reveals that certain limiting factors exist that prevent the dual fuel engine from performing as well as the superior gas engine. On the other hand, the potential is already present for the dual fuel concept to compete with the diesel engine. Since the injection of pilot fuel is of major importance for flame initialization and thus for the main combustion event of the dual fuel engine, optical investigations in a spray box, measurements of injection rates and 3D-CFD simulation were conducted to obtain even more detailed insight into these processes. A study on the influence of the diesel fraction shows that diminishing the diesel fraction from 3 % to lower values has a significant impact on engine performance because of the effects of such a reduction on injection, ignition delay and initial flame formation. An investigation of the influence of the injection timing reveals that with diesel fractions of ≤ 1.5 %, the well-known relationship between the injection timing and combustion phasing of conventional engine concepts is no longer valid. The presented results illustrate which operating strategy is beneficial for engine performance in terms of low NOx emissions and high efficiency. Moreover, potential measures can be derived which allow for further optimization of the diesel-gas combustion process.

This work explores the role of the ignition quality of a fumigated fuel on combustion phasing and brake thermal efficiency (BTE), which was investigated in a 2.5L turbocharged common rail light-duty diesel engine. Different combinations of dimethyl ether (DME) and propane were fumigated into the intake air and displaced some of the directly injected ultra-low sulfur diesel fuel (ULSD) needed to maintain the engine and a constant speed and load. Fumigation of DME and propane significantly increased BTE and reduced brake specific energy consumption (BSEC) compared to the baseline diesel condition with no fumigation. A mixture of 20% DME with 30% propane provided the maximum BTE, with 24% reduction in BSEC, however, at the expense of increasing peak cylinder pressure by 6 bar, which was even higher at greater DME substitutions. Fumigated DME auto-ignited early, ahead of top dead center (TDC), showing the typical low temperature and high temperature heat release events and propane addition suppressed the early low temperature heat release (LTHR), shifting more of the DME heat release closer to TDC. Total hydrocarbon emissions increased while NOx emissions reduced with increasing fumigation.

<div class="section abstract"><div class="htmlview paragraph">The internal combustion engine (ICE) has long dominated the heavy-duty sector by using liquid fossil fuels such as diesel but global commitments by countries and OEMs to reduce lifecycle carbon dioxide (CO₂) emissions has garnered interest in alternative fuels like hydrogen. Hydrogen is a unique gaseous fuel that contains zero carbon atoms and has desired thermodynamic properties of high energy density per unit mass and high flame speeds. However, there are challenges related to its adoption to the heavy-duty sector as a drop-in fuel replacement for compression ignition (CI) diesel combustion given its high autoignition resistance. To overcome this fundamental barrier, engine manufacturers are exploring dual fuel combustion engines by substituting a fraction of the diesel fuel with hydrogen which enables fuel flexibility when there is no infrastructure and retrofittability to existing platforms. This work studies the implications of mixing port-injected hydrogen fuel in a large-bore rail engine operating with hydrogen-diesel dual fuel combustion. Previous work was done to validate a single-cylinder computational model to data collected on this engine when operating with dual fuel combustion of natural gas and diesel. This model was then modified to employ gaseous hydrogen as the port injected fuel. First, a grid sensitivity study was performed, and it was concluded that the computational mesh was refined enough to minimize numerical error. Modeling implications are then investigated by comparing two RANS turbulence models in terms of their prediction of turbulent mixing predictions of hydrogen and air. It was seen that both had minimal differences in bulk mass flow trends, but choice of RANS turbulence model could impact qualitative predictions of fuel-air stratification. Lastly, hydrogen injection timing and flow rate were varied, and it was concluded that the highest injection flow rate is best for both premixing hydrogen with air and reducing hydrogen mass left in the intake. Additionally, given the potential limitations of hydrogen injection pressure, injection timing can be advanced to allow more time for mixing when injection velocity is maximized.</div></div>