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Director at Integrated Transport Reserch Lab, at KTH Royal Institute of Technology.
The sustainable and continuous development of public transport systems is crucial to ensuring robust and resilient transport and economic activity whilst improving the urban environment. Through technological improvement, cities can increase the competitiveness of public transport, promote equality and pursue a multi-modal shift to greener solutions. The introduction of vehicle automation technology into existing public transport systems has potential impacts on mobility behaviours and may replace conventional bus service in the future. This study examines travellers’ preferences for automated buses versus conventional buses, using a context-dependent stated choice experiment. This experiment measured the effects of context variables (such as trip purpose, travel distance, time of day, weather conditions and travel companion) on the choice of automated buses versus conventional buses. The results were analysed using mixed logit models, and the findings indicate that, in general, choice behaviours do not diverge much between the choice of automated bus and conventional bus. However, individuals’ choices are more elastic towards the changes in automated bus service levels compared to conventional bus service. The results show that poor weather conditions may lower the quality and reliability of public transport service, and the probability of choosing an automated bus over a conventional bus is reduced due to such disruptions. In addition, passengers travelling for work purposes, covering long distances, or travelling with companions are more likely to choose conventional buses than automated buses.
Jia Guo; Yusak Susilo; Constantinos Antoniou; Anna Pernestål. When and why do people choose automated buses over conventional buses? Results of a context-dependent stated choice experiment. Sustainable Cities and Society 2021, 69, 102842 .
AMA StyleJia Guo, Yusak Susilo, Constantinos Antoniou, Anna Pernestål. When and why do people choose automated buses over conventional buses? Results of a context-dependent stated choice experiment. Sustainable Cities and Society. 2021; 69 ():102842.
Chicago/Turabian StyleJia Guo; Yusak Susilo; Constantinos Antoniou; Anna Pernestål. 2021. "When and why do people choose automated buses over conventional buses? Results of a context-dependent stated choice experiment." Sustainable Cities and Society 69, no. : 102842.
Introduction The first wave of COVID-19 pandemic period has drastically changed people’s lives all over the world. To cope with the disruption, digital solutions have become more popular. However, the ability to adopt digitalised alternatives is different across socio-economic and socio-demographic groups. Objective This study investigates how individuals have changed their activity-travel patterns and internet usage during the first wave of the COVID-19 pandemic period, and which of these changes may be kept. Methods An empirical data collection was deployed through online forms. 781 responses from different countries (Italy, Sweden, India and others) have been collected, and a series of multivariate analyses was carried out. Two linear regression models are presented, related to the change of travel activities and internet usage, before and during the pandemic period. Furthermore, a binary regression model is used to examine the likelihood of the respondents to adopt and keep their behaviours beyond the pandemic period. Results The results show that the possibility to change the behaviour matter. External restrictions and personal characteristics are the driving factors of the reduction in ones' daily trips. However, the estimation results do not show a strong correlation between the countries' restriction policy and the respondents' likelihood to adopt the new and online-based behaviours for any of the activities after the restriction period. Conclusion The acceptance and long-term adoption of the online alternatives for activities are correlated with the respondents' personality and socio-demographic group, highlighting the importance of promoting alternatives as a part of longer-term behavioural and lifestyle changes.
Elisa Bin; Claudia Andruetto; Yusak Susilo; Anna Pernestål. The trade-off behaviours between virtual and physical activities during the first wave of the COVID-19 pandemic period. European Transport Research Review 2021, 13, 1 -19.
AMA StyleElisa Bin, Claudia Andruetto, Yusak Susilo, Anna Pernestål. The trade-off behaviours between virtual and physical activities during the first wave of the COVID-19 pandemic period. European Transport Research Review. 2021; 13 (1):1-19.
Chicago/Turabian StyleElisa Bin; Claudia Andruetto; Yusak Susilo; Anna Pernestål. 2021. "The trade-off behaviours between virtual and physical activities during the first wave of the COVID-19 pandemic period." European Transport Research Review 13, no. 1: 1-19.
To reach the full potential of Mobility as a Service (MaaS), especially its projected positive environmental impacts, the barriers to development and implementation processes must be identified. However, studies identifying such MaaS barriers are rare. Following an interdisciplinary approach, this paper aims to bridge this gap by adding knowledge on barriers to MaaS development and implementation using four perspectives (service design, business model, user travel attitude and behavior, and system impacts). Following a systems thinking approach, the barriers are investigated at three levels (individual, organizational and societal) to show their relationships. This paper investigates a specific type of MaaS, namely Corporate Mobility as a Service (CMaaS). The results obtained by investigating a large-scale CMaaS pilot provide implications of general barriers to MaaS development and implementation. The findings presented in this paper provide knowledge and guidance to MaaS stakeholders.
Xiaoyun Zhao; Bhavana Vaddadi; Martin Sjöman; Mia Hesselgren; Anna Pernestål. Key barriers in MaaS development and implementation: Lessons learned from testing Corporate MaaS (CMaaS). Transportation Research Interdisciplinary Perspectives 2020, 8, 100227 .
AMA StyleXiaoyun Zhao, Bhavana Vaddadi, Martin Sjöman, Mia Hesselgren, Anna Pernestål. Key barriers in MaaS development and implementation: Lessons learned from testing Corporate MaaS (CMaaS). Transportation Research Interdisciplinary Perspectives. 2020; 8 ():100227.
Chicago/Turabian StyleXiaoyun Zhao; Bhavana Vaddadi; Martin Sjöman; Mia Hesselgren; Anna Pernestål. 2020. "Key barriers in MaaS development and implementation: Lessons learned from testing Corporate MaaS (CMaaS)." Transportation Research Interdisciplinary Perspectives 8, no. : 100227.
The rapid development of automated buses holds great potential for the development of transportation systems. As research into innovative forms of automated transportation systems gains momentum, it is important to understand the public’s perceptions of such public transport systems. Previous studies have contributed based on hypothetical scenarios, but not based on real observations. Based on an online survey in Stockholm in March 2019, the current research addresses this gap by investigating the public’s perceptions from a real, fully operational, automated public transportation service operated in a mixed traffic environment on public roads. The respondents were selected along the automated bus line in Barkabystaden, Stockholm. Our findings indicate that (1) The presence of onboard operators has a positive impact on respondents’ perceived safety, (2) People who have not taken automated buses before have a more negative perception of driving speed of the bus service than people who have taken the buses before, (3) Attitudinal factors, such as public perceptions of safety, driving speed, reliability, and convenience, have a significant influence on the acceptance of the new bus system, (4) As an emerging and innovative transportation mode, automated buses are expected to attract a high share of regular public transportation mode users and the younger generations in the future, (5) Social-demographic characteristics such as gender and income had no significant impacts on the adoption of the new technology. The results provide the characteristics of early bus adopters and their travel behavior and help to prioritize possible investments and allow the policymakers and private industries to identify the special needs of users.
Jia Guo; Yusak Susilo; Constantinos Antoniou; Anna Pernestål Brenden. Influence of Individual Perceptions on the Decision to Adopt Automated Bus Services. Sustainability 2020, 12, 6484 .
AMA StyleJia Guo, Yusak Susilo, Constantinos Antoniou, Anna Pernestål Brenden. Influence of Individual Perceptions on the Decision to Adopt Automated Bus Services. Sustainability. 2020; 12 (16):6484.
Chicago/Turabian StyleJia Guo; Yusak Susilo; Constantinos Antoniou; Anna Pernestål Brenden. 2020. "Influence of Individual Perceptions on the Decision to Adopt Automated Bus Services." Sustainability 12, no. 16: 6484.
Introduction Travel demand and travel satisfaction of a transport service are affected by user perceptions of the service quality attributes, and such perceptions should be included in studying user willingness-to-pay (WTP) for automated vehicle (AV) services. This study applied structural equation modelling with service quality attribute perceptions as latent variables affecting WTP. Objectives We investigated how WTP AV services are affected by socio-demographic characteristics, knowledge and experiences with AV, existing travel modes and particularly, perceptions of the associated service quality attributes. The AV services are: 1) on-demand personalised AV (PAV) service, 2) demand responsive shared AV (SAV) service, and 3) first−/last-mile automated bus (AB) service. Methods The data were collected from 584 potential users of a first−/last-mile AB service trial operated in Kista, Stockholm. Results Results show people hold different expectations towards each type of AV service. These expectations act as the minimum requirements for people to pay for the AV services. Respondents are found to be willing to pay more for PAV service if it is safe, provides good ride comfort, and is competitively priced relative to the price travelling by metro and train over a same distance. Other than service quality attribute perceptions, income level, existing travel modes for daily trips, familiarity with automated driving technology and AB ride experience are important factors affecting WTP for the AV services. Conclusion The developed model can be applied to understand expectations of potential users towards a new AV service, and to identify user groups who are willing to pay the service. New AV services can thus be designed sensibly according to users’ actual needs.
Pei Nen Esther Chee; Yusak Octavius Susilo; Yiik Diew Wong; Anna Pernestål. Which factors affect willingness-to-pay for automated vehicle services? Evidence from public road deployment in Stockholm, Sweden. European Transport Research Review 2020, 12, 1 -17.
AMA StylePei Nen Esther Chee, Yusak Octavius Susilo, Yiik Diew Wong, Anna Pernestål. Which factors affect willingness-to-pay for automated vehicle services? Evidence from public road deployment in Stockholm, Sweden. European Transport Research Review. 2020; 12 (1):1-17.
Chicago/Turabian StylePei Nen Esther Chee; Yusak Octavius Susilo; Yiik Diew Wong; Anna Pernestål. 2020. "Which factors affect willingness-to-pay for automated vehicle services? Evidence from public road deployment in Stockholm, Sweden." European Transport Research Review 12, no. 1: 1-17.
Mobility as a Service (MaaS), where different shared modes of transportation are bundled into one easily accessible service, plays an important role in the shift towards more sustainable transport systems. In this article, we present empirical research with the aim to understand how the barriers to increased shared travel with MaaS can be lowered. The concept of corporate MaaS (CMaaS) is introduced, and empirical results are presented from a study of CMaaS at a workplace of 14,000 employees in Sweden. The findings are based on 77 interviews with CMaaS users, performed in four iterative rounds using service design methods. Social practice theories are used as analytical lens to attempt to understand travel practices in the context of CMaaS. As CMaaS (and MaaS) are socio-technical systems, several perspectives need to be integrated in order to reach this understanding; all system components, including materials (e.g. the user application, the transport modes), competences (knowledge of how to use the materials), and meanings (understandings of travel habits, lifestyle choices, and employer relations) need to be analysed. Through this analytical lens, three barriers to adoption of CMaaS and sustainable transport were identified: inadequate integration of the internal transport system with external transport systems; corporate policy, culture and norms that conflict with using the services; and system limitations due to laws and regulations. All these barriers are also relevant for understanding MaaS services in general.
Mia Hesselgren; Martin Sjöman; Anna Pernestål. Understanding user practices in mobility service systems: Results from studying large scale corporate MaaS in practice. Travel Behaviour and Society 2019, 21, 318 -327.
AMA StyleMia Hesselgren, Martin Sjöman, Anna Pernestål. Understanding user practices in mobility service systems: Results from studying large scale corporate MaaS in practice. Travel Behaviour and Society. 2019; 21 ():318-327.
Chicago/Turabian StyleMia Hesselgren; Martin Sjöman; Anna Pernestål. 2019. "Understanding user practices in mobility service systems: Results from studying large scale corporate MaaS in practice." Travel Behaviour and Society 21, no. : 318-327.
Anna Pernestål; Ida Kristoffersson; Lars-Göran Mattsson. Where will self-driving vehicles take us? Scenarios for the development of automated vehicles with Sweden as a case study. Autonomous Vehicles and Future Mobility 2019, 17 -32.
AMA StyleAnna Pernestål, Ida Kristoffersson, Lars-Göran Mattsson. Where will self-driving vehicles take us? Scenarios for the development of automated vehicles with Sweden as a case study. Autonomous Vehicles and Future Mobility. 2019; ():17-32.
Chicago/Turabian StyleAnna Pernestål; Ida Kristoffersson; Lars-Göran Mattsson. 2019. "Where will self-driving vehicles take us? Scenarios for the development of automated vehicles with Sweden as a case study." Autonomous Vehicles and Future Mobility , no. : 17-32.
The development of driverless vehicles is fast, and the technology has the potential to significantly affect the transport system, society and environment. However, there are still many open questions regarding what this development will look like and there are several counteracting forces. This paper addresses the effects of driverless vehicles by performing a literature review of twenty papers that use simulation to model effects of driverless vehicles. By combing and analysing the results from these simulation studies, an overall picture of the effects of driverless vehicles is presented. The paper shows that focus in existing literature has been on effects of driverless taxi applications in urban areas. Some parameters, such as trip cost and waiting time, show small variations between the reviewed papers. Other parameters, such as vehicle kilometres travelled (VKT), show larger variations and depend heavily on the assumptions concerning value of time and level of sharing. In general, increases in VKT are predicted for most applications. Ride sharing has the potential to reduce VKT, and thereby energy consumption and congestion, but the analysis indicates that a sufficient level of ride sharing to reduce VKT will not be achieved without incentives or regulations. Furthermore, the VKT of driverless vehicles is unevenly distributed from a time and space perspective, with larger increases in VKT during peak hours than in off-peak, and in the suburbs compared to city centres. The reviewed papers provide a first prediction of factors such as waiting time, VKT and trip cost, in particular for urban areas and for schemes where there is one service provider present. To get a deeper understanding of the effects of driverless vehicles, aspects such as local spatial considerations, e.g. at pick-up stations, and more complex schemes with competition between service providers should be studied. Furthermore, there is a need for sensitivity analyses regarding travel demand.
Anna Pernestål; Ida Kristoffersson. Effects of driverless vehicles: A review of simulations. 2018, 1 .
AMA StyleAnna Pernestål, Ida Kristoffersson. Effects of driverless vehicles: A review of simulations. . 2018; ():1.
Chicago/Turabian StyleAnna Pernestål; Ida Kristoffersson. 2018. "Effects of driverless vehicles: A review of simulations." , no. : 1.
Computer assisted troubleshooting with external interventions is considered. The work is motivated by the task of repairing an automotive vehicle at lowest possible expected cost. The main contribution is a decision theoretic troubleshooting system that is developed to handle external interventions. In particular, practical issues in modeling for troubleshooting are discussed, the troubleshooting system is described, and a method for the efficient probability computations is developed. The troubleshooting systems consists of two parts; a planner that relies on AO⁎ search and a diagnoser that utilizes Bayesian networks (BN). The work is based on a case study of an auxiliary braking system of a modern truck. Two main challenges in troubleshooting automotive vehicles are the need for disassembling the vehicle during troubleshooting to access parts to repair, and the difficulty to verify that the vehicle is fault free. These facts lead to that probabilities for faults and for future observations must be computed for a system that has been subject to external interventions that cause changes in the dependency structure. The probability computations are further complicated due to the mixture of instantaneous and non-instantaneous dependencies. To compute the probabilities, we develop a method based on an algorithm, updateBN, that updates a static BN to account for the external interventions.
Anna Pernestål; Mattias Nyberg; Håkan Warnquist. Modeling and inference for troubleshooting with interventions applied to a heavy truck auxiliary braking system. Engineering Applications of Artificial Intelligence 2012, 25, 705 -719.
AMA StyleAnna Pernestål, Mattias Nyberg, Håkan Warnquist. Modeling and inference for troubleshooting with interventions applied to a heavy truck auxiliary braking system. Engineering Applications of Artificial Intelligence. 2012; 25 (4):705-719.
Chicago/Turabian StyleAnna Pernestål; Mattias Nyberg; Håkan Warnquist. 2012. "Modeling and inference for troubleshooting with interventions applied to a heavy truck auxiliary braking system." Engineering Applications of Artificial Intelligence 25, no. 4: 705-719.
We consider computer assisted troubleshooting of complex systems, where the objective is to identify the cause of a failure and repair the system at as low expected cost as possible. Three main challenges are: the need for disassembling the system during troubleshooting, the difficulty to verify that the system is fault free, and the dependencies in between components and observations. We present a method that can return a response anytime, which allows us to obtain the best result given the available time. The work is based on a case study of an auxiliary braking system of a modern truck. We highlight practical issues related to model building and troubleshooting in a real environment.
Anna Pernestål; Håkan Warnquist; Mattias Nyberg. Modeling and Troubleshooting with Interventions Applied to an Auxiliary Truck Braking System*. IFAC Proceedings Volumes 2009, 42, 251 -256.
AMA StyleAnna Pernestål, Håkan Warnquist, Mattias Nyberg. Modeling and Troubleshooting with Interventions Applied to an Auxiliary Truck Braking System*. IFAC Proceedings Volumes. 2009; 42 (5):251-256.
Chicago/Turabian StyleAnna Pernestål; Håkan Warnquist; Mattias Nyberg. 2009. "Modeling and Troubleshooting with Interventions Applied to an Auxiliary Truck Braking System*." IFAC Proceedings Volumes 42, no. 5: 251-256.
We consider computer assisted troubleshooting of complex systems, for example of a vehicle at a workshop. The objective is to identify the cause of a failure and repair a system at as low expected cost as possible. Three main challenges are: the need for disassembling the system during troubleshooting, the difficulty to verify that the system is fault free, and the dependencies in between components and observations. We present a method that can return a response anytime, which allows us to obtain the best result given the available time. The work is based on a case study of an auxiliary braking system of a modern truck. We highlight practical issues related to model building and troubleshooting in a real environment.
Håkan Warnquist; Anna Pernestål; Mattias Nyberg. Anytime Near-Optimal Troubleshooting Applied to an Auxiliary Truck Braking System. IFAC Proceedings Volumes 2009, 42, 1306 -1311.
AMA StyleHåkan Warnquist, Anna Pernestål, Mattias Nyberg. Anytime Near-Optimal Troubleshooting Applied to an Auxiliary Truck Braking System. IFAC Proceedings Volumes. 2009; 42 (8):1306-1311.
Chicago/Turabian StyleHåkan Warnquist; Anna Pernestål; Mattias Nyberg. 2009. "Anytime Near-Optimal Troubleshooting Applied to an Auxiliary Truck Braking System." IFAC Proceedings Volumes 42, no. 8: 1306-1311.
Anna Pernestål; Mattias Nyberg. Probabilistic fault diagnosis based on incomplete training data with application to an automotive engine. 2007 European Control Conference (ECC) 2007, 1 .
AMA StyleAnna Pernestål, Mattias Nyberg. Probabilistic fault diagnosis based on incomplete training data with application to an automotive engine. 2007 European Control Conference (ECC). 2007; ():1.
Chicago/Turabian StyleAnna Pernestål; Mattias Nyberg. 2007. "Probabilistic fault diagnosis based on incomplete training data with application to an automotive engine." 2007 European Control Conference (ECC) , no. : 1.
This paper considers a Bayesian approach to fault isolation. Given a set of measurements from the system, and a set of possible faults, the task is to calculate the probability that the faults are present. This probability can then be used to rank the faults, or for decisions on fault sccomodation. The method requires the conditional probability distribution desccribing how the measurements react to the faults. In particular, the structure of dependencies between the tests is important. Knowing the structure facilitates efficient computation methods and makes it possible to reduce the memory capacity needed. In this paper, the structure is estimated from training data using Bayesian methods. The method is applied to diagnosis of the gas flow in a diesel engine.QC 2012010
Anna Pernestål; Mattias Nyberg; Bo Wahlberg. A Bayesian Approach to Fault Isolation - Structure Estimation and Inference. Fault Detection, Supervision and Safety of Technical Processes 2006 2007, 450 -455.
AMA StyleAnna Pernestål, Mattias Nyberg, Bo Wahlberg. A Bayesian Approach to Fault Isolation - Structure Estimation and Inference. Fault Detection, Supervision and Safety of Technical Processes 2006. 2007; ():450-455.
Chicago/Turabian StyleAnna Pernestål; Mattias Nyberg; Bo Wahlberg. 2007. "A Bayesian Approach to Fault Isolation - Structure Estimation and Inference." Fault Detection, Supervision and Safety of Technical Processes 2006 , no. : 450-455.
In this paper we consider Bayesian inference using training data combined with prior information. The prior information considered is response and causality information which gives constraints on the posterior distribution. It is shown how these constraints can be expressed in terms of the prior probability distribution, and how to perform the computations. Further, it is discussed how this prior information improves the inference.
Anna Pernestål; Mattias Nyberg. Using Prior Information in Bayesian Inference—with Application to Fault Diagnosis. AIP Conference Proceedings 2007, 954, 418 -426.
AMA StyleAnna Pernestål, Mattias Nyberg. Using Prior Information in Bayesian Inference—with Application to Fault Diagnosis. AIP Conference Proceedings. 2007; 954 ():418-426.
Chicago/Turabian StyleAnna Pernestål; Mattias Nyberg. 2007. "Using Prior Information in Bayesian Inference—with Application to Fault Diagnosis." AIP Conference Proceedings 954, no. : 418-426.