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On the impact of vehicle automation on the value of travel time while performing work and leisure activities in a car: Theoretical insights and results from a stated preference survey – A comment
No full textThis note revises the theoretical insights concerning the Value of Travel Time for automated vehicles as derived in a recent paper in this journal (Correia et al., 2019). That paper concluded that Value of Travel Time in an automated vehicle should be lower than in a conventional vehicle by salary rate, if the traveller works during the trip, and unchanged compared to conventional vehicles, if the traveller engages in leisure activities while travelling. However, these conclusions have limited validity, because the models, upon which they are based, contain a term whose interpretation differs across the models. This note clarifies this interpretation and offers an alternative extended model, which allows comparison across models. The alternative model provides an intuitive result: the facilitation-level of on-board activities determines the reduction of the Value of Travel Time in the automated vehicle. If automated vehicles provide identical work or leisure experience to out-of-vehicle locations, then the opportunity costs of travel time are erased and the Value of Travel Time equals the intrinsic costs of travel, which is strictly smaller than the Value of Travel Time in a conventional vehicle.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Transport and LogisticsTransport and Plannin
Time Use and Travel Behaviour with Automated Vehicles
No full textAutomated vehicles (AVs) have been a dream for a long time. From science fiction in the 1930s to countless prototypes, extensive road testing, and first use cases at present, the technology has clearly come a long way. So too has the vision of practitioners and academics matured to recognise the various potential benefits (e.g., accessibility, traffic safety, productivity, well-being) as well as threats (e.g., safety and security risks, induced travel demand, urban sprawl) of automation. The task at hand is to comprehensively assess these impacts in preparation for the AV future. In order to perform such assessment, the analyst needs to anticipate the travel behaviour and aggregate travel patterns of the future AV users. This is not a trivial task: letting go of the steering wheel may mean more than making travel more pleasant for some travellers (or perhaps less so for others who prefer to stay in control). For current car drivers, this may mean gained time and energy in a day that could let them re-optimise their activity schedule. For instance, they may choose to perform work tasks during commute, and spend less time at work as a result. That would let them increase the time spent – and potentially, trips made – for leisure. The schedule changes may be even larger for those who may become new car users with the introduction of AVs. In the aggregate, such individual-level transitions will likely form complex and significant trends in the transport system, in terms of, for example, changing person- and vehicle-kilometres, modal split, spatial and temporal distribution of travel demand and land-use patterns. How can the policy makers anticipate such complex developments? The answer to such queries has, for a long time, been provided by the coupling of travel behaviour and (large-scale) transport models. However, these models have so far been developed, successfully applied and fine-tuned for predicting travel patterns with the current, non-AV travel modes. The question that needs to be answered before using them to predict transport system developments with AVs is evident: can they reliably describe the travel behaviour of future AV users? This PhD is, for the largest part, inspired by my conviction that the answer to this question is ‘no’. In particular, I argue that the time-use dimension of travel demand models – that is, the effects of time-use in AVs on daily time-use – has not been sufficiently developed. Even state-of-the-art models commonly assume that on-board activities in AVs will lower the so-called travel time penalty or the value of travel time. In the prediction context, this inevitably leads to a prediction of more person- (and vehicle-) travel. In the evaluation context, this approach gives an illusion that the benefits from travel time savings will accrue gradually and not step-wise, due to, for example, discrete schedule re-arrangements. A simplified modelling approach such as this can bias the predictions of aggregate travel patterns, which can lead to misguided policy decisions. This thesis aims to narrow the gap between the expected travel and time-use behaviour of AV users on the one hand and the models that describe it on the other. Throughout the chapters, it, first, provides intuition that such gap indeed exists. Second, it analyses empirical evidence that partially supports this intuition. Third, it develops three time-use and travel behaviour models that incorporate some of the missing behavioural elements. Lastly, this thesis provides first insights into how these model updates make a difference for the predictions of aggregate travel patterns – a crucial input for transport policy making for the AV era.TRAIL Thesis Series no. T2021/21, the Netherlands Research School TRAILTransport and Logistic
Departure time choice and bottleneck congestion with automated vehicles: Role of on-board activities
Full text linkIt is widely expected that automated vehicles (AVs) will revolutionise travel experience by better facilitating various on-board activities. While these activities could make travel more pleasant, as is often supposed, they could also affect daily schedules, the related travel choices, and finally, the aggregate travel patterns – possible influences that are still insufficiently studied. For example, a morning commuter deciding to perform some home or work activities during travel, instead of at home or work, could also reconsider his departure time to work. More such travellers together could reshape traffic congestion. This paper models exactly this scenario. It formulates new scheduling preferences, which account for home and/or work activities during morning commute, and uses these (1) to analyse the optimal departure times when there is no congestion, and (2) to obtain the equilibrium congestion patterns in a bottleneck setting. If there is no congestion, it is predicted that AV users would depart earlier (later), if the on-board environment supports their home (work) activities. If there is congestion, AV users that perform home (work) activities during travel skew the congestion to earlier (later) times, and AV users that perform both activities increase both early and late congestion. Engaging in any activity during travel worsens congestion, at least when assuming that AVs do not increase bottleneck capacity. If future AVs would be specialised to support only home, only work, or both home and work activities, and would do so to a similar extent, then ‘Work AVs’ would increase the congestion the least.Transport and Logistic
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Solidarity in EV charging: A discrete choice experiment to assess interest in charging schemes
No full textCurrently, the electricity grid in the Netherlands is reaching its capacity, resulting in congestion issues. One of the factors that causes the electricity grid to become overloaded is the increasing use of EVs (electric vehicles). A situation in which a large number of EV users in a certain area charge their EV at the same time can significantly increase the risk of congestion in the electricity network. To avoid such situations it is necessary to change the charging behaviour of the EV users. The literature shows that smart charging systems, such as charging schemes, are having a high potential to solve these grid capacity problems. In the context of this study, a charging scheme is defined as a contract between an EV user and the charge card provider/electricity supplier stating, among others, at what times an EV user could charge his/her EV. However, to ensure that charging schemes can effectively contribute to solving the grid capacity problems, it is important that many EV users are willing to participate in such schemes. Therefore, the research objective is to study how EV users will react to various charging schemes. In particular, the aim is to assess the effectiveness of appealing to someone's intrinsic motivation versus providing extrinsic incentives. First of all, with regard to the extrinsic incentives, this study specifically concerns monetary incentives. By presenting different discounts, it is possible to test whether a monetary compensation influences the willingness to participate in a charging scheme. Secondly, with regard to someone’s intrinsic motivation, this study focuses on appealing to someone's solidarity as a form of an intrinsic motivation. EV users with a certain degree of solidarity can be motivated to participate in a charging scheme when solidarity incentives are obtained (social recognition, togetherness and the development of friendships). By emphasizing the social benefits of a charging scheme, solidarity incentives could possibly increase the willingness to participate in a charging scheme. Since the objective of the study is to research how EV users will react to various charging schemes, a survey containing a discrete choice experiment is used. To be able to examine the effectiveness of providing an extrinsic incentive (monetary compensation) versus appealing to someone's solidarity by emphasizing the social benefits of a charging scheme, the survey contains two charging scheme versions, an incentive-based version and an intrinsic-based version. By using two survey versions, it is possible to examine separately whether it is more effective to appeal to someone's intrinsic motivation versus providing a financial compensation. The results show that the willingness to participate in a charging scheme was generally higher in the intrinsic-based version than in the incentive-based version. Based on this, it can be concluded, within the boundaries of the selected attribute ranges, that appealing to someone's solidarity by emphasizing the social benefits is more effective than offering a financial compensation. This is also substantiated by the fact that the financial compensation attribute included in the incentive-based charging schemes does not influence the willingness to participate.Complex Systems Engineering and Management (CoSEM
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