Showing papers in "Transportation Research Part D-transport and Environment in 2019"

Global impacts of recent IMO regulations on marine fuel oil refining processes and ship emissions

Abstract: This study presents an overview of the context and global impacts of recent International Maritime Organization (IMO) regulations on the marine fuel oil refining industry, future marine fuel mix and ship emissions. IMO limited marine fuel sulphur content in both Sulphur Emission Control Areas (SECAs) and Nitrogen Oxide Emission Control Areas (NECAs) to 0.1% (wt. %) by 2015, and to 0.5% globally by 2020. It is anticipated that the newly implemented IMO regulations will help to mitigate negative impact of ship emissions on public health and environment. IMO regulations require significant changes to refineries to increase the production of low sulphur fuels through a shift to distillates, use of novel deep desulphurization techniques, or fuel blending. Changes to the refinery processes can bring forth increases in greenhouse gas emissions and high capital investments. Alternative fuels will need to meet the required reduction of air pollutants and greenhouse gas emissions in coastal areas. Alternative marine fuels consisting of liquefied nature gas (LNG) and biofuel may be suitable fuels to meet both targets. These two fuels are predicted to account for 50% of shipping energy demand by 2050, while the remainder will still be supplied by conventional heavy fuel oil (HFO)/marine gas oil (MGO). Switching to low sulphur fuels as a results of the new IMO regulations has led to measureable reductions in ship emissions generally. This fuel switching also resulted in changes in engine emission characteristics, especially on particulate matter chemical composition.

How much charging infrastructure do electric vehicles need? A review of the evidence and international comparison

Abstract: Plug-In electric vehicles (PEV) are in an early market phase in almost all markets. Still, the lack of public charging infrastructure is a barrier to PEV adoption. The assessment of future charging infrastructure needs is often based on key figures, mainly the ratio of PEV to public charging points. However, countries differ regarding their framework conditions, e.g. the availability of home charging, and the question of how much public charging infrastructure is needed cannot be answered equally for all countries. Yet, studies analyzing the framework conditions for the medium- to long-term demand for charging infrastructure are rare. Here, we review the existing literature and summarize the evidence for the importance of framework conditions on charging infrastructure needs. Furthermore, we illustrate the literature evidence by comparing the framework conditions for charging infrastructure in different countries based on a comprehensive dataset of framework parameters. We find public charging infrastructure as alternative to home charging is only needed in some densely populated areas. However, framework conditions vary largely among countries. Accordingly, findings from literature for specific countries can only be transferred to other countries to a limited extent.

The roles of users in electric, shared and automated mobility transitions

Abstract: This paper synthesizes insights from 19 peer-reviewed articles published in this Special Issue on the roles of users in electric, shared and automated mobility. While many researchers and stakeholders remain inspired by the potential low costs and societal benefits of these innovations, less is known about the real-world potential for uptake and usage. To better understand the likelihood and impacts of widespread uptake, we explore the perceptions of actual and potential users, including drivers, passengers, owners, and members, as well as other stakeholders such as pedestrians, planners, and policymakers. The Special Issue examines a range of cases, including plug-in electric vehicles, car-share and bike-share programs, ride-hailing and automated vehicles. For each innovation, we organize insights on user perceptions of benefits and drawbacks into four categories. Much of the research to date focuses on the first category, private-functional perceptions, mainly total cost of ownership (e.g., $/km), time use and comfort. Our synthesis however spans to the three other categories for each innovation: private-symbolic perceptions include the potential for social signaling and communicating identity; societal-functional perceptions include GHG emissions, public safety and noise; and societal-symbolic perceptions include inspiring pro-societal behavior in others, and the potential to combat or reinforce the status quo system of “automobility”. Further, our synthesis demonstrates how different theories and methods can be more or less equipped to “see” different perception categories. We also summarize findings regarding the characteristics of early users, as well as practical insights for strategies and policies seeking societally-beneficial outcomes from mass deployment of these innovations.

Energy consumption estimation integrated into the Electric Vehicle Routing Problem

Abstract: When planning routes for fleets of electric commercial vehicles, it is necessary to precisely predict the energy required to drive and plan for charging whenever needed, in order to manage their driving range limitations. Although there are several energy estimation models available in the literature, so far integration with Vehicle Routing Problems has been limited and without demonstrated accuracy. This paper introduces the Two-stage Electric Vehicle Routing Problem (2sEVRP) that incorporates improved energy consumption estimation by considering detailed topography and speed profiles. First, a method to calculate energy cost coefficients for the road network is outlined. Since the driving cycle is unknown, the model generates an approximation based on a linear function of mass, as the latter is only determined while routing. These coefficients embed information about topography, speed, powertrain efficiency and the effect of acceleration and braking at traffic lights and intersections. Secondly, an integrated two-stage approach is described, which finds the best paths between pairs of destinations and then finds the best routes including battery and time-window constraints. Energy consumption is used as objective function including payload and auxiliary systems. The road cost coefficients are aggregated to generate the path cost coefficients that are used in the routing problem. In this way it is possible to get a proper approximation of the complete driving cycle for the routes and accurate energy consumption estimation. Lastly, numerical experiments are shown based on the road network from Gothenburg-Sweden. Energy estimation is compared with real consumption data from an all-electric bus from a public transport route and with high-fidelity vehicle simulations. Routing experiments focus on trucks for urban distribution of goods. The results indicate that time and energy estimations are significantly more precise than existing methods. Consequently the planned routes are expected to be feasible in terms of energy demand and that charging stops are properly included when necessary.

Describing the users: Understanding adoption of and interest in shared, electrified, and automated transportation in the San Francisco Bay Area

Abstract: Emerging technologies and services stand poised to transform the transportation system, with large implications for energy use and mobility. The degree and speed of these impacts depend largely on who adopts these innovations and how quickly. Leveraging data from a novel survey of San Francisco Bay Area residents, we analyze adoption patterns for shared mobility, electrified vehicle technologies, and vehicle automation. We find that ride-hailing and adaptive cruise control have penetrated the market more extensively than have electrified vehicles or car-sharing services. Over half of respondents have adopted or expressed interest in adopting all levels of vehicle automation. Overall, there is substantial potential for market growth for the technologies and services we analyzed. Using county fixed effects regressions, we investigate which individual and location-level factors correlate to adoption and interest. We find that, although higher-income people are disproportionately represented among current adopters of most new technologies and services, low- to middle-income people are just as likely to have adopted pooled ride-hailing. Younger generations have high interest in automated and electrified vehicles relative to their current adoption of these technologies, suggesting that young people could contribute substantially to future market growth—as they are doing for ride-hailing. We find no evidence that longer commutes present a barrier to plug-in electric vehicle adoption. Finally, women are less likely than men to adopt and/or be interested in adopting most new transportation technologies, with the exception of ride-hailing; designing or marketing technologies with women’s preferences in mind could contribute to future market expansion.

Reviewing tools and technologies for sustainable ports: Does research enable decision making in ports?

Abstract: Ports are experiencing increased pressure to reduce negative impacts on climate and environment, and their roles and functions in transport systems and economy make them a key factor in promoting sustainability. There is substantial research on strategies and measures for mitigating emissions and pollution. This paper reviews literature on tools and technologies for sustainable ports and presents a typology based on 70 publications published in peer-reviewed journals. The paper outlines 26 tools and technologies, across four main categories (i) port management and plans, (ii) power and fuels, (iii) sea activities and (iv) land activities. The paper further discusses to what extent existing research supports port decision makers in their effort towards sustainability. We suggest that the literature gives an insufficient foundation for decision making in ports. The main reason is that few papers are based on empirical findings. We therefore suggest several avenues for addressing port sustainability in future research to enable port decision makers to select and prioritize tools or technologies: increased use of empirical data, port engagement, and understanding actors and processes in port decision making.

Travel and energy implications of ridesourcing service in Austin, Texas

Abstract: This paper identifies major aspects of ridesourcing services provided by Transportation Network Companies (TNCs) which influence vehicles miles traveled (VMT) and energy use. Using detailed data on approximately 1.5 million individual rides provided by RideAustin in Austin Texas, we quantify the additional miles TNC drivers travel: before beginning and after ending their shifts, to reach a passenger once a ride has been requested, and between consecutive rides (all of which is referred to as deadheading); and the relative fuel efficiency of the vehicles that RideAustin drivers use compared to the average vehicle registered in Austin. We conservatively estimate that TNC drivers commute to and from their service areas accounts for 19% of the total ridesourcing VMT. In addition, we estimate that TNC drivers drove 55% more miles between ride requests within 60 min of each other, accounting for 26% of total ridesourcing VMT. Vehicles used for ridesourcing are on average two miles per gallon more fuel efficient than comparable light-duty vehicles registered in Austin, with twice as many are hybrid-electric vehicles. New generation battery electric vehicles with 200 miles of range would be able to fulfill 90% of full-time drivers’ shifts on a single charge. We estimate that the net effect of ridesourcing on energy use is a 41–90% increase compared to baseline, pre-TNC, personal travel.

From value co-creation to value co-destruction? The case of dockless bike sharing in China

Abstract: Sharing-economy platforms have gained momentum in urban areas worldwide by offering the potential for efficient resource utilisation and novel value creation. A recent addition to the mobility sector of the sharing economy is the dockless bike-sharing system (DBSS), which emerged in late 2015 with the aim of complementing urban mobility and contributing to urban sustainability. However, recently, debate and controversy have emerged about the potential negative consequences of DBSS. Building on the value-creation literature, and drawing on practice theory and the resource-integration perspective, we investigate how users participate in value co-creation and co-destruction activities related to DBSS. Through a thematic analysis of 8813 social media (i.e. Sina Weibo) tweets from April 2016 to December 2017, we find that riding experience is the most important practice in the core using process for both value co-creation and co-destruction, and that post-riding practices can result in significant value co-destruction. In the value-formation process of DBSS, the critical firm resources are product–service resources and relational resources, and the critical customer resources are emotional resources, relational resources and energy resources. We also argue the enabling role of peripheral practices in the transition between value co-creation and co-destruction. We contribute to the literature by proposing a value co-creation and co-destruction framework for DBSS derived from key social practices and resources.

Technological diffusion as a process of societal embedding: Lessons from historical automobile transitions for future electric mobility

Abstract: Technological diffusion can be understood as a broader process of co-construction of technology and its environment. This article conceptualizes this co-construction as a process of societal embedding, in which new technologies find their place in wider societal domains, which include immediate user contexts, cultural meanings, policies, and infrastructures. This perspective helps address three under-developed dimensions in adoption models: (1) diffusion includes more actors than users/adopters, (2) user characteristics and environments are not known in advance, but are articulated during the technological diffusion process, and (3) societal embedding is full of choices and struggles that affect the directionality and thus shape of socio-technical systems. Societal embedding therefore calls importance to the “demand side” of sustainability transitions. Because electric vehicles have, so far, only achieved limited diffusion globally, we cannot use it to test and illustrate our framework. We therefore use a historical comparative research design, which utilizes the societal embedding framework with two case studies of automobile diffusion in the United States and the Netherlands between the 1880s and 1970s. We subsequently apply the resulting lessons and insights to the future development of electric vehicles, with examples from multiple countries. An important finding is that the successful diffusion of electric vehicles demands a more robust co-construction policy focus that includes tinkering with all aspects of the societal embedding process, and one involving a constellation of agents beyond policymakers and purchasers.

Relationship between the development and CO2 emissions of transport sector in China

Abstract: The transport sector imposes enormous challenges for energy consumption and CO2 emission reduction. Using data from 30 provinces in China, this paper adopted the Tapio decoupling index to examine the relationship between the development of the transport sector and its CO2 emissions from provincial perspective. Additionally, we employed the logarithmic mean divisia index method to explore the effect of several factors on the state of decoupling. The results showed that the under-developed provinces were more likely to present a weak decoupling state than the developed and coastal provinces. Income level was the major influential factor limiting the development of decoupling in the transport sector. The population scale had a very small negative role in the development of decoupling. Moreover, the effects of CO2 emissions efficiency, transport intensity and industry structure varied across provinces. By offering a provincial perspective on decoupling states and its driving factors, this study can provide a reference for governments in proposing carbon-reduction policies and promoting low carbon development of the transport sector.

Port sustainability and performance: A systematic literature review

Abstract: Motivated by a lack of research on port sustainability performance and assessment, this paper uses a systematic literature review to identify trends, measurement methods, and mechanisms for the implementation of strategy and policy in this area. The paper provides a comprehensive and critical evaluation of port operational sustainability, focusing on ascertaining the impact of its implementation. The study analysed and synthesised established characteristics in the current literature regarding the performance of port sustainability and its evaluation in terms of operations and management. Successful performance measurement in port sustainability is driven by the dependence on establishing accurate indicators as the basis for measurement. Our clustering of analytical sustainability indicators reveals that environmental research is focused on pollution, social research is mainly focused on human resource management, while economic research is mainly on port management and borderline investment. Findings are discussed in four key areas of port sustainability performance and assessment: existing trends, implementation of measures, mechanisms for implementation, and assessment gaps and challenges. For existing trends, attempts to evaluate the applicability and practicality of green operations have improved the awareness and promotion of governmental green policies. Implementation measures relate to the utilisation of techniques that reveal optimal practices for practical sustainable operations while mechanisms largely relate to establishing indicators which increase understanding of performance. Finally, challenges in this field include achieving consistency among ports in how sustainability is measured. Future research should incentivise improvements in port operational practice and encourage self-examination in order to reprioritise activity.

Examining threshold effects of built environment elements on travel-related carbon-dioxide emissions

Abstract: Understanding how built environment features are associated with travel-related carbon-dioxide (CO2) emissions is essential for planners to encourage environmentally sustainable travel through transportation and land use policies. Applying gradient boosting decision trees to the data from the Minneapolis-St. Paul metropolitan area, this study addresses two gaps in the literature by identifying critical built environment determinants of CO2 emissions, and more importantly, illustrating threshold effects of built environment elements. The results show that three neighborhood-level built environment factors have the strongest influences on CO2 emissions: distance to the nearest transit stop, job density, and land use diversity. The distance to downtowns also has a substantial impact. This study further confirms that built environment variables are effective only within a certain range. These threshold effects offer valuable implications for planners to achieve desirable environmental benefits efficiently.

Demand drivers for charging infrastructure-charging behavior of plug-in electric vehicle commuters

Abstract: The public as well as the private sector that includes automakers and charging network companies are increasingly investing in building charging infrastructure to encourage the adoption and use of plug-in electric vehicles (PEVs) as well as to ensure that current facilities are not congested. However, building infrastructure is costly and, like road congestion, when there is significant uptake of PEVs we may not be able to “build out of congestion.” Modelling the choice of charging infrastructure of more than 3000 PEV drivers who had the opportunity to select among home, work, and public locations, we focus on understanding the importance of factors driving demand such as: the cost of charging, driver characteristics, access to charging infrastructure, and vehicle characteristics. We find that differences in the cost of charging play an important role in the demand for charging location. PEV drivers tend to substitute toward workplace charging when they pay a higher electricity rate at home, more so when the former is free. Additionally, socio-demographic factors like dwelling type and gender, as well as vehicle technology like electric range, influence the choice of charging location.

Psychological and behavioral factors affecting electric vehicle adoption and satisfaction: A comparative study of early adopters in China and Korea

Abstract: This study compares psychological and behavioral factors affecting EV (electric vehicle) adoption and satisfaction between China, the largest EV market in the world, and Korea, a fledgling EV market. Respective samples were collected from relatively mature EV users in four major cities in China (Chinese early majority) and from members of a fledgling EV community in Korea (Korean early adopters). The results show that environmental concern is an important determinant of EV purchase for the Chinese early majority, whereas the goal of minimizing operating costs is the most important determinant for the Korean early adopters. Usage satisfaction is high in both samples, with this factor being higher for the Korean early adopters than for the Chinese early majority. Usage satisfaction is also found to be related to the original purchase motive. Finally, EV owners in both countries cited “battery range” and “battery charging” as the two most important reasons for their dissatisfaction. We suggest that the government shift its emphasis from reducing acquisition cost to reducing vehicle operating cost and increasing convenience.

Impacts of free-floating bikesharing system on public transit ridership

Abstract: The development of bike sharing system (BSS) has changed travelers’ commuting and lifestyle in recent years. Whether BSSs are complementary or competitive to public transit remains controversial. This study uses a propensity score matching-based difference-in-difference (DID) method to evaluate the impact of free-floating BSS on bus ridership in Chengdu, China. The transaction data of bus service and BSS and the neighboring points of interest are investigated. Results indicate that, (a) on the bus route level, each shared bike results in a 4.23 increment and a 0.56 reduction in daily bus ridership on weekdays and weekends, respectively; (b) on the bus stop level, the increment in shared bikes significantly negatively impacts bus ridership on weekends; (c) on the route level, regarding the time of day, each unit increment of shared bike significantly increases bus ridership on weekdays by 0.54, 0.34, and 0.15 during a.m. peak, p.m. peak, and off peak, respectively; and (d) on the bus stop level, the relationship between shared bikes and bus ridership is insignificant on weekdays. This study reveals that the demand pattern of commuters strongly impacts the relationship between shared bike and public transportation.

Effect of environmental awareness on purchase intention and satisfaction pertaining to electric vehicles in Japan

Abstract: The reduction of CO2 emission using electric vehicles (EVs) is attracting much attention as a countermeasure for global warming. In this study, we investigate the intention of non-EV owners and the post-purchase satisfaction of EV owners by conducting online survey in Japan. The structural relation of both these factors is analyzed using structural equation modeling (SEM). This analysis focuses on the environmental awareness. We compare the estimations between the purchase intentions of non-EV users and the post-purchase satisfaction of EV users. Results show that the structures of purchase intentions of non-EV users and post-purchase satisfaction of EV are different. The evaluation of EVs shows that the environmental awareness has a direct effect on the purchase intention of a non-EV user, whereas an indirect effect on the post-purchase satisfaction of a EV user.

Will consumers prefer shared and pooled-use autonomous vehicles? A stated choice experiment with Swiss households.

Abstract: Autonomous vehicles, understood as vehicles that do not require manual steering, will cause disruptive changes in the transportation sector. Many studies on autonomous vehicles address the sustainability potential of this technology, and they assume that vehicles will no longer be privately owned and will be used with pooling options (multiple riders on a trip). However, there is currently little evidence to indicate whether this assumption is supported by user preference. To address this gap, an online choice experiment including 709 participants was conducted. It assumed the full-market penetration of autonomous vehicles and explored future mode choices, considering both short-term and long-term mobility decisions. The experiment tested the influence of 15 short-term and 13 long-term decision instruments to encourage the adoption of shared and pooled use of autonomous vehicles, like autonomous taxis and autonomous public transport . Our findings partly support the assumption in the existing literature that vehicles are likely to be used in a pooled mode. In the control condition, 61% of Swiss respondents preferred pooled autonomous vehicles over private autonomous cars. Moreover, stated preferences indicated that combined instruments influencing comfort, cost, and time are likely to increase the proportion of pooled uses of autonomous vehicles.

Contributions of shared autonomous vehicles to climate change mitigation

Abstract: The climate change impacts of the anticipated growth in shared autonomous vehicles (SAVs) are highly uncertain due to competing mechanisms whose magnitudes are difficult to estimate. On the one hand, SAVs could reduce greenhouse gas emissions by driving more efficiently, avoiding traffic congestion, accelerating adoption of alternative fuel vehicles, and charging in alignment with renewable electricity generation. On the other hand, SAVs could induce more vehicle miles traveled (VMT) by lowering the time cost of travel and allowing non-drivers to travel more by car. In this study, we develop an energy system optimization model that integrates the electricity and transport sectors, computes endogenous technology adoption, and distinguishes SAVs from privately owned vehicles (POVs) to explore the contributions of SAVs to climate change mitigation. Our results show that widespread SAV adoption lowers costs and emissions, and that these desirable outcomes remain true even if SAVs induce double the VMT of the POVs they replace. SAVs dramatically accelerate the market penetration of electric vehicles. The environmental and economic benefits of this electrification trend are larger if electric SAV charging can be optimally aligned with renewable electricity generation. Especially in the short to medium term, SAV adoption can be a more impactful lever than a carbon tax for decarbonizing vehicle travel.

Who wants shared mobility? Lessons from early adopters and mainstream drivers on electric carsharing in Germany

Abstract: Shared mobility can contribute to tackling many of the pressing problems from transport and initiate a system change. But who is attracted by shared mobility and who not? How is this related to the attractiveness of electric driving? What are the perceptions underlying those preferences? We try to answer these questions based on two survey studies from Germany with a focus on carsharing. First, we present findings from an online survey (n = 1548) in one of Germany’s showcase regions for electric vehicles (EVs) to analyse the acceptance of carsharing in society. The data analysis shows that perceived compatibility with daily life is the most important factor related to the attitudes towards carsharing and that social norms also play an important role. Second, we analyse early adopters of electric carsharing, i.e. a combination of both innovations in more detail. We draw on a survey (n = 947) from field trials in Germany. We find that – extending the results of study 1 – the users are a socio-demographically specific group. A segmentation revealed that carsharing with EVs is particularly attractive for younger people who (i) live as a couple but without cars or (ii) are starting a family and use carsharing as a supplement to their own cars. The findings from the second study are in line with the first one and also emphasise that the affinity for carsharing and EVs is closely connected. We conclude the paper by discussing the implications of our findings for the transition to low-carbon mobility.

Investigating end-user acceptance of autonomous electric buses to accelerate diffusion

Abstract: To achieve the widespread diffusion of autonomous electric buses (AEBs) and thus harness their environmental potential, a broad acceptance of new technology-based mobility concepts must be fostered. Still, there remains little known about the factors determining their acceptance, especially in the combination of vehicles with alternative fuels and autonomous driving modes, as is the case with AEBs. In this study, we first conducted qualitative research to identify relevant factors influencing individual acceptance of autonomously driven electric buses. We then developed a comprehensive research model that was validated through a survey of 268 passengers of an AEB, operated in regular road traffic in Germany. The results indicate that a mix of individual factors, social impacts, and system characteristics determine an individual’s acceptance of AEBs. Notably, it is important that users perceive AEBs, not only as advantageous, but also trustworthy, enjoyable, and in a positive social light. Our research supplements the existing corpora by demonstrating the importance of individual acceptance and incorporating it to derive policy implications.

Who will be the early adopters of automated vehicles? Insights from a survey of electric vehicle owners in the United States

Abstract: Most major automakers are developing vehicles with some level of automated driving capability. These vehicles range from those with adaptive cruise control to full driverless vehicles. These vehicles are collectively referred to as automated vehicles. The adoption of automated vehicles by consumers is not well understood. It is likely that the first buyers will be typical early adopters i.e. consumers who have different lifestyles, attitudes, and socio-demographic profiles compared to the general population. Using a questionnaire survey of 2715 consumers in 36 states in the USA, we investigate the attitudes of early adopters of one automotive technology: plug-in electric vehicles (PEVs). This sample was selected so that the perceptions and purchase intentions of early adopters could be investigated. This is opposed to assessing the attitudes of the public who are unlikely to be knowledgeable about automated vehicles and unable to accurately assess the vehicles and estimate their own purchase intentions. This study finds that PEV early adopters have positive perceptions of automated vehicles. However, being a PEV adopter does not necessarily lead to interest in purchasing an automated vehicle. PEV adopters are clustered into 5 different groups with differing levels of interest in automated vehicles (from “Pioneers” to “Laggards”). The results suggest that automated vehicles are likely to be purchased by a small group of pioneering consumers. These “Pioneers” are likely to be high income consumers, with good knowledge and positive perceptions of the automated vehicles (on safety, comfort, and purchase price), and positive attitudes towards technology in general.

Measuring progress towards transport sustainability through indicators: Analysis and metrics of the main indicator initiatives

Abstract: Transport is widely considered as a sector with significant positive and negative externalities affecting society, environment and economy. The fact of incorporating the main principles of sustainable development into transport planning is of prime importance. However, moving towards transport sustainability is a challenging task; it requires a paradigm shift as well as the constant monitoring and intensive evaluation of the current conditions through broadly accepted methodological tools such as indicators. In this context, the scope of the current research is to provide a complete picture of the approaches which aim at measuring progress towards transport sustainability as well as facilitating the development of new initiatives by highlighting the major trends. Consequently, a considerable number (78) of sustainable transport indicator initiatives were selected through an extensive literature review. Accordingly, descriptive statistics was used regarding the main features of the examined initiatives, while an analysis focused on the 2644 included indicators was subsequently implemented. The current research illustrates the linkages among the sustainability pillars and the selected objectives/themes. It also points out the great variability regarding the hierarchical structure, categorizes the considerable number of themes found in the literature into smaller groups, presents the most commonly used themes and indicators, and finally proposes an alternative categorization of weighting schemes concerning indexes. An attempt has been made so that this study can become a meaningful operational tool for researchers aiming at promoting the relevant research by contributing to the selection of the most suitable yet compatible and scientifically valid methods for each case.

Life cycle assessment of city buses powered by electricity, hydrogenated vegetable oil or diesel

Abstract: This study explores life cycle environmental impacts of city buses, depending on the: (1) degree of electrification; (2) electricity supply mix, for chargeable options; and (3) choice of diesel or hydrogenated vegetable oil (HVO), a biodiesel, for options with combustion engine. It is a case study, which uses industry data to investigate the impact on climate change, a key driver for electrification, and a wider set of impacts, for average operation in Sweden, the European Union and the United States of America. The results show that non-chargeable hybrid electric vehicles provide clear climate change mitigation potential compared to conventional buses, regardless of the available fuel being diesel or HVO. When fueling with HVO, plug-in hybrid and all-electric buses provide further benefits for grid intensities below 200 g CO2 eq./kWh. For diesel, the all-electric option is preferable up to 750 g CO2 eq./kWh. This is the case despite batteries and other electric powertrain parts causing an increase of CO2 emissions from vehicle production. However, material processing to make common parts, i.e. chassis, frame and body, dominates the production load for all models. Consequently, city buses differ from passenger cars, where the battery packs play a larger role. In regard to other airborne pollutants, the all-electric bus has the best potential to reduce impacts overall, but the results depend on the amount of fossil fuels and combustion processes in the electricity production. For toxic emissions and resource use, the extraction of metals and fossil fuels calls for attention.

Electric vehicle charging point placement optimisation by exploiting spatial statistics and maximal coverage location models

Abstract: Electric vehicles (EVs) are increasingly considered as a promising solution to tackle climate change impacts , improve air quality, and enhance growth sustainability. This paper proposes a two-step approach for optimally deploying charging points (CPs) by bringing together spatial statistics and maximal coverage location models. CP locations are conceptualised as a spatial point pattern, driven by an underlying stochastic process , and are investigated by using a Bayesian spatial log-Gaussian Cox process model. The spatial distribution of charging demand is approximated by the predicted process intensity surface of CP locations, upon which a maximal coverage location model is formulated and solved to identify optimal CP locations. Drawing upon the large-scale urban point of interest (POI) data and other data sources, the developed method is demonstrated by exploring the deployment of CPs in London. The results show that EV charging demand is statistically significantly associated with workplace population density, travel flows, and densities of three POI categories (transport, retail and commercial). The robustness of model estimation results is assessed by running spatial point process models with a series of random subsets of the full data. Results from a policy scenario analysis suggest that with increasing numbers of charging stations to be planned, optimal CP locations gradually expand to the suburban areas of London and the marginal gains in charging demand covered decrease rapidly.

Quantifying air quality benefits resulting from few autonomous vehicles stabilizing traffic

Abstract: It is anticipated that in the near future, the penetration rate of vehicles with some autonomous capabilities (e.g., adaptive cruise control, lane following, full automation, etc.) will increase on roadways. This work investigates the potential reduction of vehicular emissions caused by the whole traffic stream, when a small number of autonomous vehicles (e.g., 5% of the vehicle fleet) are designed to stabilize the traffic flow and dampen stop-and-go waves. To demonstrate this, vehicle velocity and acceleration data are collected from a series of field experiments that use a single autonomous-capable vehicle to dampen traffic waves on a circular ring road with 20 to 21 human-piloted vehicles. From the experimental data, vehicle emissions (hydrocarbons, carbon monoxide, carbon dioxide, and nitrogen oxides) are estimated using the MOVES emissions model. This work finds that vehicle emissions of the entire fleet may be reduced by between 15% (for carbon dioxide) and 73% (for nitrogen oxides) when stop-and-go waves are reduced or eliminated by the dampening action of the autonomous vehicle in the flow of human drivers. This is possible if a small fraction (∼5%) of vehicles are autonomous and designed to actively dampen traffic waves. However, these reductions in emissions apply to driving conditions under which stop-and-go waves are present. Less significant reductions in emissions may be realized from a deployment of AVs in a broader range of traffic conditions.

How will automated vehicles shape users’ daily activities? Insights from focus groups with commuters in the Netherlands

Abstract: non-driving activities while travelling, such as working, sleeping, playing games. The impact of this possibility on the satisfaction with travel and on travel demand has been extensively discussed in the literature. However, it has been hardly recognised that the availability of on-board activities influences the (time-geographic) constraints of daily activities and may alter the selection, location, and sequencing of other activities in the day. This hampers correct representation of travel behaviour in activity-based models aiming to predict the effects of AVs on mobility and environment (e.g., greenhouse gas emissions). To help fill this gap, we gathered and analysed qualitative data from focus groups, in which 27 commuters discussed their expectations concerning on-board activities and daily schedules in the AV-era. Among the core insights are the following three. First, it is useful to separate in modelling the satisfaction with travel and the potential for on-board activities during travel: they have different determinants and different consequences for activity schedules and individual travel demand. Second, on-board activities may be classified in 4 quadrants according to their novelty and priority level: this classification is helpful in understanding the potential re-arrangements of daily activities. Third, performing new activities during travel may lead to complex re-arrangements of daily activity patterns; the re-arrangements may ease or also increase time pressure. These, and other reported insights may facilitate more realistic representation of activity-travel behaviour in future travel behaviour models.

The effect of electrified mobility on the relationship between traffic conditions and energy consumption

Abstract: Decreasing road transport's harmful effects on environment and health and reducing road accidents are major policy priorities. A variety of technologies could drastically improve air quality, reduce energy consumption and CO2 emissions of road vehicles: in this respect, a prominent trend leverages Electric Vehicles (EVs), supported by improved performance and energy efficiency through connectivity and automation. A noteworthy research question in the transition from Internal Combustion Engine Vehicles (ICEVs) to the alternative technologies, is to understand how Intelligent Transport Systems and other traffic-related measures can contribute to the reduction of fuel consumption and greenhouse gas emissions. In fact, a widely acknowledged tenet assumes that congestion removal or mitigation in presence of ICEVs implies also a reduction of transport-related externalities. This paper explores whether this effect still holds for EVs, by performing an analysis of energy consumption over different vehicle trajectories, under both congested and free-flow conditions. Calculations are carried out using two vehicle simulators: the VT-CPEM (Virginia Tech Comprehensive Power-based Energy consumption model) model for EVs and the CO2MPAS (CO2 model for Passenger and commercial vehicle Simulation) vehicle simulator for the ICEVs, for both electric and conventional cases passengers and freight/commercial powertrains have been analysed. Results are presented on real and simulated data related to four powertrain-vehicle combinations, in terms of general trends of energy/fuel consumption versus speed. Interestingly, results show that, differently from ICEVs, the relationship between congestion and energy consumption underlying EVs can change with higher energy consumption connected to an increased average traffic speed.

Electric vehicles in the last mile of urban freight transportation: A sustainability assessment of postal deliveries in Rio de Janeiro-Brazil

Abstract: The growth of urban population and the rise of e-commerce activities increase the complexity of the last-mile of parcel deliveries and its impacts to the environment and quality of life. Despite the relevance, emerging countries have difficult to establish and implement alternatives to the conventional scope of fossil-based operations. This paper proposes a method to assess alternative strategies for the last-mile of parcel deliveries, in terms of social, environmental, and economic impacts and presents an application to assess the distribution strategy of a postal company located in the city of Rio de Janeiro, Brazil. Moreover, we developed a systematic literature review to develop realistic alternatives to the baseline scenario, which operates with diesel propelled light duty vehicles. Literature points to the reduction of the dimensions of vehicles, as well as to the migration of the propulsion source to electric energy, as sustainable alternatives for last mile deliveries in urban areas. For that reason, we opted to evaluate the use of electric vehicles of smaller dimensions, tricycle and LDV, in the last mile of parcel deliveries, assessing two alternative scenarios: one with the use of electric LDV type BEV; and the other with electric tricycles. Results indicated that the use electric tricycle is a more feasible alternative regarding the economic, environmental and social aspects, demanding no public incentives.

An environmental and economic analysis of methanol fuel for a cellular container ship

Abstract: In this study, the use of methanol is proposed as an alternative fuel to comply with the international maritime organization (IMO) emission regulations. Environmental and economic analysis of the methanol-diesel dual fuel engine is carried out. As a case study, cellular container ship is investigated. The results show environmental benefits for reducing NOx, SOx , CO , CO 2 , and PM emissions by 76.78%, 89%, 55%, 18.13%, and 82.56%, respectively. In order to reduce the dual-fuel cost to the cost of the diesel fuel at maximum continuous rating (MCR), the ship speed should be reduced by 28%. In addition, the currently operated diesel engine uses selective catalytic reduction method (SCR) to comply with the IMO emission regulations. Combining the benefits of ship slow steaming and the saved SCR costs, the cost-effectiveness of dual-fuel engine for reducing NO x, CO, and CO2 emissions will be 385.2 $/ton, 6548 $/ton, and 39.9 $/ton, respectively.

Examining the effects of the built environment on auto ownership in two Norwegian urban regions

Abstract: Based on a study in the Oslo and Stavanger metropolitan areas in Norway combining quantitative and qualitative methods, this paper sheds light on influences of built environment characteristics on auto ownership. In both metropolitan areas, the distance from the dwelling to the main city center, a measure of regional destination accessibility, has an important effect on auto ownership. A quasi-longitudinal analysis shows that outward residential relocation tends to increase auto ownership and inward relocation to reduce it. Neighborhood density variables including population and employment also exert important influences. The analysis of qualitative interview material substantiates the causal mechanism about the effects of the built environment characteristics on auto ownership.