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D. Milakis

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Changes in expert opinions over time

Journal article (2023) - Maarten Kroesen, Dimitris Milakis, Bert van Wee
Innovations in transportation can contribute to reaching relevant societal objectives (e.g. reduce emissions, congestion levels and/or risks). To determine which innovations to stimulate (and which not) it is important for policy makers to assess their effects on beforehand. Expert judgement is an often-used method for this purpose. Although expert opinions can provide useful input for decision-making, these judgement are potentially subject to change, for example, due to new information becoming available or because the (academic) discussion about the innovation in question takes a new turn. Studies that explicitly study stability and change in expert judgements are rare, but highly relevant to determine the reliability of experts' assessments. To address this gap, this study assesses experts’ judgments at multiple points in time focusing on the effects of a transport innovation with potentially widespread societal implications, namely Automated Vehicles (AVs). To this end a survey was administrated to a group of experts involved in the WISE-ACT project. The results indicate that expert opinions towards this innovation are generally favorable; AVs are believed to reduce congestion delays, greenhouse gas emissions and traffic accidents. Although the consulted experts are generally quite stable in their opinions, they are becoming less optimistic about these positive effects over time. A Q-factor analysis additionally reveals two clusters of experts, one with a positive and one a negative outlook on AVs. The latter group beliefs that AVs will lower the value of travel time, thereby increasing travel demand, and, in turn, emission and congestion levels. Overall, the changing and diverging opinions among experts indicate that the transition to AVs is not necessarily regarded as a desirable one. ...

Unanticipated implications for society and governance

Journal article (2020) - Kate Pangbourne, Miloš N. Mladenović, Dominic Stead, Dimitris Milakis
In this paper we focus on the development of a new service model for accessing transport, namely Mobility as a Service (MaaS) and present one of the first critical analyses of the rhetoric surrounding the concept. One central assumption of one prevalent MaaS conceptualization is that transport services are bundled into service packages for monthly payment, as in the telecommunication or media service sectors. Various other forms of MaaS are being developed but all tend to offer door-to-door multi-modal mobility services, brokered via digital platforms connecting users and service operators. By drawing on literature concerned with socio-technical transitions, we address two multi-layered questions. First, to what extent can the MaaS promises (to citizens and cities) be delivered, and what are the unanticipated societal implications that could arise from a wholesale adoption of MaaS in relation to key issues such as wellbeing, emissions and social inclusion? Second, what are de facto challenges for urban governance if the packaged services model of MaaS is widely adopted, and what are the recommended responses? To address these questions, we begin by considering the evolution of intelligent transport systems that underpin the current vision of MaaS and highlight how the new business model could provide a mechanism to make MaaS truly disruptive. We then identify a set of plausible unanticipated societal effects that have implications for urban planning and transport governance. This is followed by a critical assessment of the persuasive rhetoric around MaaS that makes grand promises about efficiency, choice and freedom. Our conclusion is that the range of possible unanticipated consequences carries risks that require public intervention (i.e. steering) for reasons of both efficiency and equity. ...
Journal article (2019) - Dimitris Milakis
Journal article (2018) - Kees van Goeverden, Dimitris Milakis, Milan Janic, Rob Konings
Introduction: Hyperloop (HL) is presented as an efficient alternative of HSR (High Speed Rail) and APT (Air Passenger Transport) systems for long-distance passenger transport. This paper explores the performances of HL and compares these performances to HSR and APT. Methods: The following performances of the HL system are analytically modeled and compared to HSR and APT: (i) operational performance; (ii) financial performance; (iii) social/environmental performance. Results: The main operational result is that the capacity of HL is low which implies a low utilization of the infrastructure. Because the infrastructure costs dominate the total costs, the costs per passenger km are high compared to those for HSR and APT. The HL performs very well regarding the social/environmental aspects because of low energy use, no GHG emissions and hardly any noise. The safety performance needs further consideration. Conclusions: The HL system is promising for relieving the environmental pressure of long-distance travelling, but has disadvantages regarding the operational and financial performances. ...

A critical reflection on challenges for urban transport and mobility governance

Book chapter (2018) - Kate Pangbourne, Dominic Stead, Miloš Mladenović, Dimitris Milakis
This chapter provides a reflective critique of Mobility as a Service (MaaS), an emerging development seeking a role within the Smart Mobility paradigm. We assess a range of its future implications for urban policymakers in terms of governance and sustainability (i.e., social and environmental impacts). We begin by describing the origins of the MaaS concept, along with the features of precursor technologies and current early examples. We then reflect on the marketing of MaaS and use it to consider how we might anticipate some potentially less desirable aspects of the promoted business models. Finally, we discuss the implications for governance. ...
Abstract (2018) - Kees van Goeverden, Milan Janic, Dimitris Milakis
Long-distance travelling accounts for a significant and increasing part of the mileage of person travel and the respective environmental impacts (Van Goeverden et al, 2016). Energy consumption and emissions connected with long-distance travelling might be substantially reduced through use of evacuated tubes of low air resistance, such as the recently proposed Hyperloop transport system (HL). This paper explores the extent to which a fully developed HL network system in Europe could reduce energy consumption and GHG emissions of long-distance passenger transport. ...

Exploring the acceptable travel time concept in the US and European contexts

Journal article (2018) - Dimitris Milakis, Bert van Wee
Milakis et al. (2015b) explored the acceptable travel time concept as a possible factor in the travel and destination decision-making process. These researchers employed both theory and methods triangulation to assess the validity of this concept. Results from interviews with 20 subjects in Berkeley, CA supported the acceptable travel time concept. In this paper, the US study is replicated in Europe (Delft, The Netherlands) to further explore the validity of the acceptable travel time concept, compare results between Delft and Berkeley, and to identify possible factors influencing the acceptable travel time. Results of this study offer support for the validity of the acceptable travel time concept. The subjects in Delft appeared to be less satisfied with longer commute times than the subjects in Berkeley. Urban, transport as well as sociocultural factors might explain this variation in acceptable travel times. ...
Journal article (2018) - Jurgen Nieuwenhuijsen, Gonçalo Homem de Almeida Correia, Dimitris Milakis, Bart van Arem, Els van Daalen
This paper presents a novel simulation model that shows the dynamic and complex nature of the innovation system of vehicle automation in a quantitative way. The model simulates the innovation diffusion of automated vehicles (AVs) on the long-term. It looks at the system of AVs from a functional perspective and therefore categorizes this technology into six different levels. Each level is represented by its own fleet size, its own technology maturity and its own average purchase price and utility. These components form the core of the model. The feedback loops between the components form a dynamic behavior that influences the diffusion of AVs. The model was applied to the Netherlands both for a base and an optimistic scenario (strong political support and technology development) named “AV in-bloom”. In these experiments, we found that the system is highly uncertain with market penetration varying greatly with the scenarios and policies adopted. Having an ‘AV in bloom’ eco-system for AVs is connected with a great acceleration of the market take-up of high levels of automation. As a policy instrument, a focus on more knowledge transfer and the creation of an external fund (e.g. private investment funds or European research funds) has shown to be most effective to realize a positive innovation diffusion for AVs. Providing subsidies may be less effective as these give a short-term impulse to a higher market penetration, but will not be able to create a higher market surplus for vehicle automation. ...
Journal article (2018) - Dimitris Milakis, Maarten Kroesen, Bert van Wee
In this paper, possible accessibility impacts of fully automated vehicles (AVs) are explored. A conceptual framework for those impacts is developed based on the model of four accessibility components (i.e. land use, transport, temporal and individual) of Geurs and van Wee (2004). Q-method is applied among a sample of seventeen international accessibility experts to explore heterogeneity among experts with respect to the impacts of AVs on accessibility, and study different views and clusters of experts. Q-method statements are deductively categorized according to four accessibility components of the conceptual framework. Three viewpoints were extracted, indicating that experts expect AVs to influence accessibility through all four accessibility components. Viewpoint A expects that accessibility benefits stemming from AVs will be highly uncertain, mainly because of induced travel demand that will likely cancel out travel time and cost savings of AVs in the long term. Viewpoint B anticipates that accessibility changes because of AVs will have two opposing implications for urban form: densification of city center and further urban sprawl. Finally, viewpoint C expects that those who can afford an AV will mainly enjoy AVs benefits, thus AVs will have more negative than positive implications for social equity. ...

Quasi-Longitudinal analysis of links in the case of Greeks relocating from US to Greece

Journal article (2017) - Dimitris Milakis, Dimitrios Efthymiou, Constantinos Antoniou
In this study, the possible causal links between the built environment, travel attitudes and travel behaviour of people that have moved between totally different urban and transportation contexts were investigated. A quasi-longitudinal design was developed to collect data about the perceived neighbourhood characteristics, neighbourhood preferences, travel attitudes and changes in car, walking and bicycle usage of 51 Greeks who relocated from the US to Greece. Variable reduction techniques were applied prior to developing our models because of the small sample size. The results of this study offer support for a causal relationship between the built environment and travel behaviour identified in the existing literature. For instance, longer travel time to city center was associated with higher car use, higher density neighbourhoods and increased accessibility to local amenities were associated with increased bike use and better access to a district shopping center was associated with more walking after relocation. Our results also showed that in contexts like Greece, where transport infrastructures are not adequately developed, lack of safe bike conditions and easy access to public transportation are important determinants of bicycle use and walking. Thus, according to our results, promoting sustainable mobility in contexts like Greece would require not only enhancing accessibility through relocation of activities, but also by improving infrastructures for public transport, bicycle and walking. ...

Bridging the implementation gap

Journal article (2017) - Cecília Silva, Luca Bertolini, Marco te Brömmelstroet, Dimitris Milakis, Enrica Papa
Accessibility concepts are increasingly acknowledged as fundamental to understand cities and urban regions. Accordingly, accessibility instruments have been recognised as valuable support tools for land-use and transport planning. However, despite the relatively large number of instruments available in the literature, they are not widely used in planning practice. This paper aims to explore why accessibility instruments are not widely used in planning practice. To this end we focus our research on perceived user-friendliness and usefulness of accessibility instruments. First, we surveyed a number of instrument developers, providing an overview on the characteristics of accessibility instruments available and on developers’ perceptions of their user-friendliness in planning practice. Second, we brought together developers and planning practitioners in a number of local workshops across Europe and Australia, where participants were asked to use insights provided by accessibility instruments for the development of planning strategies. We found that most practitioners are convinced of the usefulness of accessibility instruments in planning practice, as they generate new and relevant insights for planners. Findings suggest that not only user-friendliness problems, but mainly organizational barriers and lack of institutionalization of accessibility instruments, are the main causes of the implementation gap. Thus user-friendliness improvement may provide limited contributions to the successful implementation of accessibility concepts in planning practice. In fact, there seems to be more to gain from active and continued engagement of instrument developers with planning practitioners and from the institutionalization of accessibility planning. ...
Journal article (2017) - Dimitris Milakis, Maaike Snelder, Bart Van Arem, Bert Van Wee, Gonçalo Homem De Almeida Correia
Automated driving technology is emerging. Yet, little is known in the literature about when automated vehicles will reach the market, how penetration rates will evolve and to what extent this new transport technology will affect transport demand and planning. This study uses scenario analysis to identify plausible future development paths of automated vehicles in the Netherlands and to estimate potential implications for traffic, travel behaviour and transport planning on a time horizon up to 2030 and 2050. The scenario analysis was performed through a series of three workshops engaging a group of diverse experts. Sixteen key factors and five driving forces behind them were identified as critical in determining future development of automated vehicles in the Netherlands. Four scenarios were constructed assuming combinations of high or low technological development and restrictive or supportive policies for automated vehicles (AV …in standby, AV …in bloom, AV …in demand, AV …in doubt). According to the scenarios, fully automated vehicles are expected to be commercially available between 2025 and 2045, and to penetrate the market rapidly after their introduction. Penetration rates are expected to vary among different scenarios between 1% and 11% (mainly conditionally automated vehicles) in 2030 and between 7% and 61% (mainly fully automated vehicles) in 2050. Complexity of the urban environment and unexpected incidents may influence development path of automated vehicles. Certain implications on mobility are expected in all scenarios, although there is great variation in the impacts among the scenarios. Measures to curb growth of travel and subsequent externalities are expected in three out of the four scenarios. ...

A review of literature and directions for future research

Journal article (2017) - Dimitris Milakis, Bart van Arem, Bert van Wee
In this paper, the potential effects of automated driving that are relevant to policy and society are explored, findings discussed in literature about those effects are reviewed and areas for future research are identified. The structure of our review is based on the ripple effect concept, which represents the implications of automated vehicles at three different stages: first-order (traffic, travel cost, and travel choices), second-order (vehicle ownership and sharing, location choices and land use and transport infrastructure) and third-order (energy consumption, air pollution, safety, social equity, economy and public health). Our review shows that first-order impacts on road capacity, fuel efficiency, emissions and accidents risk are expected to be beneficial. The magnitude of these benefits will likely increase with the level of automation and cooperation and with the penetration rate of these systems. The synergistic effects between vehicle automation, electrification and sharification can multiply these benefits. However, studies confirm that automated vehicles can induce additional travel demand because of more and longer vehicle trips. Potential land use changes have not been included in these estimations about excessive travel demand. Other third-order benefits on safety, economy, public health and social equity still remain unclear. Therefore, the balance between the short-term benefits and long-term impacts of vehicle automation remains an open question. ...
Conference paper (2017) - Kees van Goeverden, Dimitris Milakis, Milan Janic, Rob Konings
This paper deals with an analysis of performances of the HL (Hyperloop) transport system considered as an advanced transport alternative to the existing APT (Air Passenger Transport) and HSR (High Speed Rail) systems. The considered performances are operational, financial, social and environmental. The operational performance include capacity and quality of service provided to the system’s users-passengers with attributes such as door-to-door travel time consisting of the access and egress time, schedule delay, in-vehicle time, and interchange time. The economic performances embrace the costs and revenues of operating the system. The costs include that for infrastructure, vehicles, traffic management facilities and equipment, and employees. The revenues embrace earnings from pricing users/passengers. The environmental performances include energy consumption and related emissions of GHGs (Green House Gases), and land use. The social performances are considered to be noise and safety. The analytical models of indicators of these performances are developed and applied to the scenario of operating the HL system on the short- to medium-haul travel distances/routes. These are then compared to the corresponding performances of the HSR and APT. This comparison has shown that the HL system may possess some advantages but also disadvantages regarding particular performances. ...
Book chapter (2016) - Gonçalo Homem de Almeida Correia, Dimitris Milakis, Bart van Arem, Raymond Hoogendoorn
Other (2016) - Dimitris Milakis
Conference paper (2016) - Dimitris Milakis, Bert van Wee
“Do people consider an acceptable travel time?” We raised this question in Milakis, Cervero, and van Wee (2015) to explore the validity of the acceptable travel time concept as a possible factor in the travel and destination decision-making process. Results from interviews with 20 subjects in Berkeley, CA supported this concept. In this paper we replicate the US study in Europe (Delft, The Netherlands) to (a) further test the acceptable travel time concept in European context and (b) compare results between Delft and Berkeley to gain more insights into this theoretical concept. Results of this study confirm the validity of the acceptable travel time concept. Also, additional evidence shows that acceptable travel time can vary with travel mode. Subjects in Delft have on average a higher acceptable commute time than subjects in Berkeley. Urban, transport as well as sociocultural factors might explain this variation in acceptable travel times. ...

The synergies of social and built environment

Abstract (2016) - E. Chrysikou, Dimitris Milakis, C. Tziraki-Segal
Aims
Despite the fact that the WHO stresses the role of the built environment as key determinant for an autonomous life in wellbeing, architecture and health still are not connected in architectural and medical education and as a result in architectural and medical practice. This paper aims toDespite the fact that the WHO stresses the role of the built environment as key determinant for an autonomous life in wellbeing, architecture and health still are not connected in architectural and medical education and as a result in architectural and medical practice. This paper aims to provide a targeted overview of the theory for the need to educate and create a dialogue between designers, healthcare professionals and entrepreneurs of retirement and chronic facility sector.
Theoretical approach
The paper puts together the existing architectural thinking such as space syntax, normalization theory, architectural guidelines for dementia, universal design and accessibility theories and juxtaposes them to the cognitive and physical evolution of human needs throughout the lifespan, as expressed by the current medical evidence base. It cherry-picks the elements that each theory could contribute to a fit for purpose design practice that would be in accordance to the recent demographical shift.
Conclusions
The paper stresses the fact that a more inclusive architecture that is in line with the perception and the physiological needs of the people throughout their lifespan could create domestic, healthcare and public environments that work in synergies with medical and technological interventions through a mechanism of enabling. These solutions could be low cost or even noadding- cost compared to conventional architecture but require a shift in design methodologies of all scales to more evidence-based and inclusive perspectives.
provide a targeted overview of the theory for the need to educate and create a dialogue
between designers, healthcare professionals and entrepreneurs of retirement and chronic
facility sector.
Theoretical approach
The paper puts together the existing architectural thinking such as space syntax, normalization
theory, architectural guidelines for dementia, universal design and accessibility theories and
juxtaposes them to the cognitive and physical evolution of human needs throughout the
lifespan, as expressed by the current medical evidence base. It cherry-picks the elements that
each theory could contribute to a fit for purpose design practice that would be in accordance to
the recent demographical shift.
Conclusions
The paper stresses the fact that a more inclusive architecture that is in line with the perception
and the physiological needs of the people throughout their lifespan could create domestic,
healthcare and public environments that work in synergies with medical and technological
interventions through a mechanism of enabling. These solutions could be low cost or even noadding-
cost compared to conventional architecture but require a shift in design methodologies
of all scales to more evidence-based and inclusive perspectives. ...