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  • 1.
    Abadir Guirgis, Georg
    Swedish National Road and Transport Research Institute, Traffic and road users, Human-vehicle-transport system interaction.
    Lärarperspektiv på riskutbildningen för motorcyklister2011Report (Other academic)
    Abstract [en]

    Over the last decade it has become increasingly popular to ride a motorcycle in Sweden. A mandatory risk education for competence A and A1 was introduced from the 1st of November 2009. Since the education is new, few evaluations have been conducted so far.

    This study evaluates the risk education for motorcyclists based on the perspective of driving instructors. The goal was to compile the instructors' comments and experiences with respect to the new risk training. An additional objective was to examine the driving instructors' perceived effects of the education on their students' driving behavior. Six semi-structured interviews with driving instructors and an observational study of the education at various driving schools were conducted. In addition, a participant observation study was performed during a further education of 15 driving instructors. The results show that the instructors experience a great need for the new risk training and that the implementation of the training itself has been good. Students have been referring to the risk training, which according to the instructors indicate that the students have embraced the essence of the training. As a result, the students drive more carefully now and think twice in certain situations according to the instructors. This was considered a desirable result.

  • 2.
    Abadir Guirgis, Georg
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Human-vehicle-transport system interaction.
    Peters, Björn
    Swedish National Road and Transport Research Institute, Traffic and road users, Human-vehicle-transport system interaction.
    Simulatorbaserad utbildning i ERTMS: utvärdering av utbildning och träning för lokförare i VTI:s tågsimulator2015Report (Other academic)
    Abstract [en]

    The purpose of this study was to evaluate the VTI train simulator with regard to simulator-based training and education in the ERTMS (European Rail Traffic Management System) system for train drivers, compared to the ERSA simulator. The purpose was also to study two different ways of combining theoretical education with practical training in a simulator. In the future, the major railway routes in Sweden will be equipped with ERTMS. This will require considerable training for Sweden’s approximately 3,500 train drivers in future need of ERTMS education. It is unrealistic to think that these should be trained on real tracks. Therefore, there is a need for a more realistic ERTMS simulator compared to the European Rail Software Applications (ERSA) simulator that Trafikverket provides. The study was conducted as a between group design with two measurements. Three different groups were compared under different conditions. Theoretical education in ERTMS combined with training in the ERSA simulator (group 0), theoretical education in ERTMS ending with training in the VTI-simulator (group 1) and theoretical education in ERTMS partly alternated with training in the VTI-simulator (group 2).

  • 3.
    Abadir Guirgis, Georg
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Human-vehicle-transport system interaction.
    Peters, Björn
    Swedish National Road and Transport Research Institute, Traffic and road users, Human-vehicle-transport system interaction.
    Lidström, Mats
    Swedish National Road and Transport Research Institute, Traffic and road users, Vehicle technology and simulation.
    Lokförarutbildning i Sverige: simulatoranvändning och ERTMS2014Report (Other academic)
    Abstract [en]

    This report, which provides an overview of the compulsory basic training for train drivers in Sweden, highlights the occurrence of simulator-based training in education, along with the training efforts being made with regards to the future introduction of ERTMS/ETCS. The report also shows the possibilities and limitations of increased use of simulators in driver training and describes the most important governing documents for train drivers and train driver training. Furthermore, the Swedish Transport Agency curriculum for train driver licenses is presented along with the institutions engaged in basic education, training and examination of train driver’s. Also, the Swedish Transport Administration’s E-learning tool for ERTMS, the ERSA-simulator and company specific ERTMS education at SJ and Green Cargo are described. Moreover, Swedish train companies’ and educators’ current use and future needs of simulators for train driver training were examined. Examples from other domains where simulators are used in a training context are also presented.

  • 4.
    Abate, Megersa
    Swedish National Road and Transport Research Institute, Society, environment and transport, Transport economics Stockholm.
    Determinants of Capacity Utilisation in Road Freight Transportation2014In: Journal of Transport Economics and Policy, ISSN 0022-5258, E-ISSN 1754-5951, Vol. 48, p. 137-152Article in journal (Refereed)
    Abstract [en]

    Recent performance indicators in the European road freight transport sector show there is an excess capacity. To shed light on this, this paper studies two aspects of capacity utilisation in trucking: the extent of empty running and the load factor. Using a joint econometric modelling framework, the paper shows that they can be explained as a function of haul, carrier, and truck characteristics. For estimation, a unique dataset from the Danish heavy vehicle trip diary was used. The results indicate distance and being a for-hire carrier have a positive effect on capacity utilisation, whereas the effect of truck size is non-linear.

  • 5.
    Abate, Megersa
    Swedish National Road and Transport Research Institute, Society, environment and transport, Transport economics, TEK.
    Does fuel price affect trucking industry’s network characteristics?: evidence from Denmark2014Report (Other academic)
    Abstract [en]

     The 2000s were dominated by rising fuel prices and economic recession. Both had an impact on the structure of the trucking industry and how freight was moved. This paper examines how fuel prices shaped trucking industry’s network characteristics such as the average length of haul, average load, and capacity utilization. In particular, we show the effect of fuel price on average length of haul using 29 quarterly independent surveys from the Danish heavy goods vehicle (HGV) trip diary from 2004 to 2011. The results show that the average length of haul is sensitive to changes in fuel price: a DKK 1 (0.18$) increase in diesel price/liter leads to a 4 percent decrease in the average length of haul in the 2004-2007 period. This implies that firms improve transport efficiency by reducing the number of kilometers needed to transport a tonne of cargo as a short run response to fuel price increases. This result, however, is not confirmed for the years following the 2008 financial crisis. It also depends on where in the distribution of the average length of haul one looks.

  • 6.
    Abate, Megersa
    Swedish National Road and Transport Research Institute, Society, environment and transport, Transport economics, TEK.
    Economic effects of air transport market liberalization in Africa2016In: Transportation Research Part A: Policy and Practice, ISSN 0965-8564, E-ISSN 1879-2375, Vol. 92, p. 326-337Article in journal (Refereed)
    Abstract [en]

    Although the aviation industry is increasingly becoming important for Africa's economic development and integration, the ability of airlines to access foreign markets remains hindered by restrictive regulatory policies. Attempts have been made to fully liberalize the intra-African air transport market. Except for general assertions about the merits/demerits of liberalization, our empirical understanding of the welfare effects of such polices in Africa remains rudimentary. This study empirically measures the economic effects of air transport liberalization, mainly on two supply side variables: fare and service quality, measured as departure frequency. The empirical models evaluate how air fares and departure frequency respond to measures of openness in air services agreements, while controlling for other determinants. The results show up to 40% increase in departure frequency in routes that experienced some type of liberalization compared to those governed by restrictive bilateral air service agreements. Furthermore, there is a relatively larger increase in departure frequency in routes which experienced partial liberalization compared to fully liberalized ones. This can be explained by the diminishing marginal effect of progressive liberalization on departure frequency. While the effect of liberalization is substantial in improving service quality, there is no evidence of its fare reducing effect.

  • 7.
    Abate, Megersa
    Swedish National Road and Transport Research Institute, Society, environment and transport, Transport economics, TEK.
    Economic effects of air transport market liberalization in Africa2014Report (Other academic)
    Abstract [en]

    Although the aviation industry is increasingly becoming important for Africa's economic development and integration, the ability of airlines to access foreign markets remains hindered by restrictive regulatory policies. Attempts have been made to fully liberalize the intra-African air transport market. Except for general assertions about the merits/demerits of liberalization, our empirical understanding of the welfare effects of such polices in Africa remains rudimentary. This study empirically measures the economic effects of air transport liberalization, mainly on two supply side variables: fare and service quality, measured as departure frequency. The results show up to 40 % increase in departure frequency in routes that experienced some type of liberalization compared to those governed by restrictive bilateral air service agreements. While the effect of liberalization is substantial in improving service quality, there is no evidence of its fare reducing effect.

  • 8.
    Abate, Megersa
    et al.
    Swedish National Road and Transport Research Institute, Society, environment and transport, Transport economics Stockholm.
    De Jong, Gerard
    University of Leeds.
    The optimal shipment size and truck size choice: The allocation of trucks across hauls2014In: Transportation Research Part A: Policy and Practice, ISSN 0965-8564, E-ISSN 1879-2375, Vol. 59, p. 262-277Article in journal (Refereed)
    Abstract [en]

    There has been a growing interest in understanding how firms allocate their trucks across hauls, and how this allocation changes under various economic environments. This study investigates how variations in route/haul, carrier and vehicle characteristics affect the optimal vehicle size choice and the associated choice of shipment size. We show that the two choices are derived from the same optimization problem. There can be a continuum of shipment sizes, but decision-makers in freight transport have to choose from a limited number of vehicle alternatives. Therefore, we use a discrete-continuous econometric model where shipment size is modeled as a continuous variable, and vehicle size/type choice as a discrete variable. The results indicate that when faced with higher demand, and during longer trips firms are more likely to use heavier vehicles and ship in larger quantities which suggest that firms are realizing economies of scale and economies of distance. The study also discusses the effect of vehicle operating cost on the vehicle selection process and its policy implications.

  • 9.
    Abate, Megersa
    et al.
    Swedish National Road and Transport Research Institute, Society, environment and transport, Transport economics Stockholm.
    Vierth, Inge
    Swedish National Road and Transport Research Institute, Society, environment and transport, Transport economics Stockholm.
    de Jong, Gerard
    University of Leeds.
    Joint econometric models of freight transport chain and shipment size choice2014Report (Other academic)
    Abstract [en]

    In freight transportation, decisions regarding the choice of transport mode (or chains of modes) and shipment size are closely linked. Building on this basic insight, in this paper we estimate and review various joint econometric models using the Swedish National Commodity Flow surveys. Robust parameter estimates from this exercise will be used to update the current deterministic Swedish national freight model system (the SAMGODS model) to a stochastic one.

  • 10.
    Abrahamsson, Anna
    Swedish National Road and Transport Research Institute.
    Hastigmätares felvisning1991Report (Other academic)
  • 11.
    Abrahamsson, Anna
    Swedish National Road and Transport Research Institute.
    Metod för skattning av åtgärdseffekten vid saltning av vägar1989Report (Other academic)
  • 12.
    Abrahamsson, Anna
    et al.
    Swedish National Road and Transport Research Institute.
    Junghard, Ola
    Swedish National Road and Transport Research Institute.
    Reducerat faktorförsök med foldover för VTIs trafiksimuleringsmodell1992Report (Other academic)
  • 13.
    Abrahamsson, Anna
    et al.
    Swedish National Road and Transport Research Institute.
    Ohlsson, Kjell
    Swedish National Road and Transport Research Institute.
    Sjölinder, Kent
    Swedish National Road and Transport Research Institute.
    Litteratursökning gällande olycksprediktionsmodeller och riskindex för plankorsningar mellan väg och järnväg1991Report (Other academic)
  • 14.
    Abtahi, Farhad
    et al.
    Kungliga Tekniska Högskolan.
    Anund, Anna
    Swedish National Road and Transport Research Institute, Traffic and road users, Human Factors in the Transport System.
    Fors, Carina
    Swedish National Road and Transport Research Institute, Traffic and road users, Human Factors in the Transport System.
    Seoane, Fernando
    Kungliga Tekniska Högskolan.
    Lindecrantz, Kaj
    Kungliga Tekniska Högskolan.
    Association of drivers’ sleepiness with heart rate variability: A pilot study with drivers on real roads2018In: IFMBE Proceedings, Springer Verlag , 2018, Vol. 65, p. 149-152Conference paper (Refereed)
    Abstract [en]

    Vehicle crashes lead to huge economic and social consequences, and one non-negligible cause of accident is driver sleepiness. Driver sleepiness analysis based on the monitoring of vehicle acceleration, steering and deviation from the road or physiological and behavioral monitoring of the driver, e.g., monitoring of yawning, head pose, eye blinks and eye closures, electroencephalogram, electrooculogram, electromyogram and electrocardiogram (ECG), have been used as a part of sleepiness alert systems.

    Heart rate variability (HRV) is a potential method for monitoring of driver sleepiness. Despite previous positive reports from the use of HRV for sleepiness detection, results are often inconsistent between studies. In this work, we have re-evaluated the feasibility of using HRV for detecting drivers’ sleepiness during real road driving. A database consists of ECG measurements from 10 drivers, driving during morning, afternoon and night sessions on real road were used. Drivers have reported their average sleepiness level by using the Karolinska sleepiness scale once every five minutes. Statistical analysis was performed to evaluate the potential of HRV indexes to distinguish between alert, first signs of sleepiness and severe sleepiness states. The results suggest that individual subjects show different reactions to sleepiness, which produces an individual change in HRV indicators. The results motivate future work for more personalized approaches in sleepiness detection.

  • 15.
    Achwan, Nawawi
    et al.
    Swedish National Road and Transport Research Institute.
    Lanalywati,
    Swedish National Road and Transport Research Institute.
    Application and development of road safety audit in Indonesia2001Report (Other (popular science, discussion, etc.))
    Abstract [sv]

    The high rate of road accidents in Indonesia have become a national problem,

    which need serious handling. One of the causes, beside the human and vehicle

    factor, is the road and environmental factor. Based on international

    research, the contribution of road and environmental factors is calculated to

    24 %. This in turns stresses the importance of a strategy, which in the end

    lead to the improvement of road safety conditions through application of a

    road safety concept. The author strongly argues in favour of Road Safety

    Audits. A safety audit process could be applied at all stages - in the

    feasibility study before the road is constructed or rehabilitated, during all

    of the design phases and after the road have been in operation. Furthermore,

    this paper introduces the concept of road safety audit with an existing by

    pass road in Cirebon as an example.

  • 16.
    Adell, Emeli
    et al.
    Trivector Traffic.
    Nilsson, Annika
    Trivector Traffic.
    Kircher, Katja
    Swedish National Road and Transport Research Institute, Traffic and road users, Human-vehicle-transport system interaction.
    Cyclists' use of mobile IT in Sweden: usage and self-reported behavioural compensation2014In: 3rd International Cycling Safety Conference (ICSC2014), 18-19 November, Gothenburg, Sweden: proceedings, Gothenburg, Sweden, 2014Conference paper (Refereed)
    Abstract [en]

    The increasing use of mobile phones while cycling has raised safety concerns. In this paper two studies of mobile phone use by cyclists are presented.

    The first study was designed to characterize mobile phone use by cyclists in Sweden, while the second studied how mobile phone use affected cyclist behaviour and compensation strategies. Mobile phone use was observed in about 20 percent of all urban bicycle trips. The usage varied with cyclist age with the highest usage among young cyclists. Of those using phones, 90% of the cyclists observed used head-phones.

    In parallel, standardized, interviews 15% of cyclists under 15 years old stated that they always used mobile phones while cycling. Listening to music in headphones was the most fre-quent self-reported activity. To converse using hand-held phones was also rather common, and was the only mobile phone usage reported by women above 50 years old.

    In the second study twenty-two young cyclists (age 16-25 years) completed a route in real traffic five times while listening to music, receiving and making calls, receiving and sending text messages, searching for information on the internet and while cycling normally without using the phone. The route and the types of tasks were controlled, but the cyclists could choose rather freely when, where and how to carry out the tasks. When the cyclist returned to the starting point, a short interview was conducted. During the interviews cyclists reported their experiences and the compensation strategies they used while cycling.

  • 17.
    Adell, Emeli
    et al.
    Trivector Sweden.
    Nilsson, Lena
    Swedish National Road and Transport Research Institute, Traffic and road users.
    Várhelyi, András
    Lund University.
    How Is Acceptance Measured?: Overview of Measurement Issues, Methods and Tools2014In: Driver Acceptance of New Technology: Theory, Measurement and Optimisation / [ed] Michael A. Regan, Tim Horberry and Alan Stevens, Farnham, Surrey, England: Ashgate, 2014, p. 74-88Chapter in book (Refereed)
    Abstract [en]

    This chapter describes how acceptance has been measured and identifies various measurement categories. The relationship between these measurement methods and the different definitions of acceptance appearing in the literature is described and the lack of correspondence between definition and measurement is highlighted. The chapter illustrates the different outcomes of acceptance measurements depending on choice of assessment method and gives some guidance that could be used depending on the purpose of the assessment.

  • 18.
    Adell, Emeli
    et al.
    Trivector Sweden.
    Várhelyi, András
    Lund University.
    Nilsson, Lena
    Swedish National Road and Transport Research Institute, Traffic and road users.
    Modelling Acceptance of Driver Assistance Systems: Application of the Unified Theory of Acceptance and Use of Technology2014In: Driver Acceptance of new technology: Theory, Measurement and Optimisation / [ed] Michael A. Regan, Tim Horberry and Alan Stevens, Farnham, Surrey, England: Ashgate, 2014, p. 23-34Chapter in book (Refereed)
    Abstract [en]

    This chapter provides a brief overview of acceptance models used within the area of information technology.  One particular model, the Unified Theory of Acceptance and Use of Technology (UTAUT), is then discussed, and a study is reported in which the model was used to assess driver acceptance of a particular driver assistance system. The key findings of that study are reported, and suggestions are made for refining UTAUT to make it more suitable for assessing acceptance of driver assistance systems.

     

  • 19.
    Adell, Emeli
    et al.
    Trivector Sweden.
    Várhelyi, András
    Lunds Universitet.
    Nilsson, Lena
    Swedish National Road and Transport Research Institute, Traffic and road users.
    The Definition of Acceptance and Acceptability2014In: Driver Acceptance of New Technology: Theory, Measurement and Optimisation / [ed] Michael A. Regan, Tim Horberry and Alan Stevens, Farnham, Surrey, England: Ashgate, 2014, p. 11-21Chapter in book (Refereed)
    Abstract [en]

    Despite the recognised importance of the concept of acceptance, how and why new technologies are actually accepted by drivers is not well understood. While many studies claim to have measured acceptance, few have explicitly defined what it is. This chapter points out the importance of defining acceptance and categorises definitions that have been used according to their “essence”. Distinctions between different types of acceptance as well as between acceptance and acceptability are also described. A proposal for a common definition of acceptance is then presented and discussed.

  • 20. Adesiyun, Adewole
    et al.
    Bezuglyi, Artem
    Bidnenko, Natalya
    Laszlo, Gaspar
    Golovko, Sergyi
    Kraszewski, Cezary
    Krayushkina, Kateryna
    Kushnir, Olexander
    Kuttah, Dina K
    Swedish National Road and Transport Research Institute, Infrastructure, Pavement Technology.
    Niska, Anna
    Swedish National Road and Transport Research Institute, Infrastructure, Infrastructure maintenance.
    Sörensen, Gunilla
    Swedish National Road and Transport Research Institute, Traffic and road users, Traffic safety, society and road-user.
    Szpikowski, Miroslaw
    Andrezj, Urbanik
    Voloshyna, Iryna
    Vozniuk, Andrii
    Vyrozhemsky, Valeriy
    Short-term Research Visits2014Report (Other (popular science, discussion, etc.))
  • 21. Admasie, D
    et al.
    Stenberg, L
    Swedish National Road and Transport Research Institute.
    Equipment for frost heave tests: Friction between plastic and soil1982Report (Other academic)
  • 22.
    Adolph, Thorsten
    et al.
    Federal Highway Research Institute.
    Eggers, Andre
    Federal Highway Research Institute.
    Thomson, Robert William
    Swedish National Road and Transport Research Institute, Traffic and road users, Traffic safety, society and road-user.
    Mizuno, Koji
    Nagoya University.
    Comparison of the dummy response in two different restraint system crash tests2014In: 2014 IRCOBI Conference Proceedings - International Research Council on the Biomechanics of Injury, 2014, p. 545-561Conference paper (Refereed)
    Abstract [en]

    In the European Project FIMCAR, a proposal for a frontal impact test configuration was developed which included an additional full width deformable barrier (FWDB) test. Motivation for the deformable element was partly to measure structural forces as well as to produce a severe crash pulse different from that in the offset test. The objective of this study was to analyse the safety performance of vehicles:

    • in the full width rigid barrier test (FWRB) and
    • in the full width deformable barrier test (FWDB)

    In total, 12 vehicles were crashed in both configurations. Comparison of these tests to real world accident data was used to identify the crash barrier most representative of real world crashes. For all vehicles, the airbag visible times were later in the FWDB configuration. This was attributed to the attenuation of the initial acceleration peak, observed in FWRB tests, by the addition of the deformable element. These findings were in alignment with airbag triggering times seen in real world crash data. Also, the dummy loadings were slightly worse in FWDB compared to FWRB tests, which is possibly linked to the airbag firing and a more realistic loading of the vehicle crash structures in the FWDB configuration. Evaluations of the lower extremities have shown a general increasing of the tibia index with the crash pulse severity.

  • 23.
    Ahlberg, Joakim
    Swedish National Road and Transport Research Institute, Society, environment and transport, Transport economics Stockholm. Örebro universitet, Handelshögskolan vid Örebro Universitet.
    Analysis of discrete multi-unit, common value auctions: a study of three sealed-bid mechanisms2012Manuscript (preprint) (Other academic)
    Abstract [en]

    This paper proposes a discrete bidding model for both quantities and pricing. It has a two-unit demand environment where subjects bid for contracts with an unknown redemption value, common to all bidders. Prior to bidding, the bidders receive private signals of information on the (common) value. The value and the signals are drawn from a known discrete affiliated joint distribution. The relevant task for the paper is to compare the equilibrium strategies and the seller’s revenue of three auction formats. We find that, of the three auctionformats below with two players, the discriminatory auction always gives the largest revenue to the seller; both the uniform and the Vickrey auction have zero revenue equilibrium strategies that put them further down in the revenue ranking. In equilibrium, bidders bid the same amount on both items in the discriminatory auction; a phenomenon not noted in either of the other auction formats.

  • 24.
    Ahlberg, Joakim
    Swedish National Road and Transport Research Institute, Society, environment and transport, Transport economics, TEK.
    Energimätning på tåg för rundvirkestransporter på sträckan Mora–Borlänge–Gävle2014Report (Other academic)
    Abstract [en]

    The third sub-project of ELVIS demonstration project for longer and heavier freight trains aims to analyze and measure energy usage of heavier trains. With heavier refers to a higher overall weight by more wagons, both loaded and unloaded, than would normally run on the route. The assumption is that heavier trains are able to do (freight) transport more energy efficient. The goal is to primarily test the hypothesis: · That energy consumption per ton can be reduced by using heavier trains. The report also illustrates the difficulties of using existing data for the evaluation of energy consumption on trains. The data in these has not been quality assured for the purposes of this study, which has caused a lot of errors and the credibility of some results are lower than otherwise would be needed. Thus, a conclusion from the project is that it would take a review of the databases of the Swedish Transport Administration on energy use should be studied further, at least if equipment such as their energy meter should be used. Alternatively, mount external equipment on locomotives to thereby generate more useful data; the latter, however, was not possible due to the owner of the locomotive. Given all sources of error associated with the data, the report analyze how the energy of a freight train is due to the gross weight of the train, the number of stops the train makes and drivers' driving style. Findings were that driving style plays a major role, between drivers the different in net energy used is up to 20 percent. Furthermore, there is differences in energy consumption connected to gross weights on the train, but then it's a bit unclear how the results should be interpreted in conjunction with the lack of quality of the data, it takes more measurements to be able to say anything definite. The same applies to the number of stops affecting the use of energy. On the first leg the number of stops had no impact on energy consumption, which it had on the investigation route.

  • 25.
    Ahlberg, Joakim
    Swedish National Road and Transport Research Institute, Society, environment and transport, Transport economics, TEK.
    Intermodala transporter: definition, aktörer och omfattning2016Report (Other academic)
    Abstract [en]

    Intermodal and combined transport is often used synonymously today. The concept of combined transport has been around much longer and referred to as transportation where railway and a truck are being combined. Nowadays a combined transport often means that the goods either go by rail, inland waterways or sea and by road, or between two transport modes where trucks are not included. Intermodal and combined transport is often used synonymously today. The concept of combined transport has been around much longer and referred to as transportation where railway and a truck are being combined.

    Nowadays a combined transport often means that the goods either go by rail, inland waterways or sea and by road, or between two transport modes where trucks are not included. The EU’s so-called combi directive defines both in the same way and one of the EU Commission’s proposal to amend this directive is that EU should be considered to replace the concept of combined transport with intermodal transport. An intermodal transport precedes by a transportation decision, and this decision is often linked to a specific train path (tågläge in Swedish). If there is shortage of capacity on the track, the goods may have difficulties to be transported by train. This could potentially mean that some (rail) business / transports will not take place and the goods go by road instead.

  • 26.
    Ahlberg, Joakim
    Swedish National Road and Transport Research Institute, Society, environment and transport, Transport economics, TEK.
    Kostnader för störningar i infrastrukturen: metodik och fallstudier på väg och järnväg2015Report (Other academic)
    Abstract [en]

    The purpose of this study is to illustrate the methodology that can be used in calculations of the cost to society when disruptions in the infrastructure occurs, specifically for traffic on road and rail. The principles and values that are recommended to be used in social cost-benefit analyses (CBA) in the Swedish transport sector are proposed by the ASEK-group (a working-group addressing issues on the application of CBA in the transport sector), and decided by the Swedish Transport Administration. They will be taken as given on the cost side of the CBA in this study, there will not be a benefit side since the interest for this study lies expressively on the cost side. This study is thus not a normative analysis, the aim is instead to study and apply methodologies for valuing (in monetary terms) the consequences of already occurred disturbances. The various ASEK-values require information about several aspect of the trips when calculating the value of travel time and transport time, as well as when calculating the delays and the value of travel time savings in congestion. Even though the ASEK-values are recommended by the Swedish Transport Administration, they are also questioned, especially for freight transport. This is also addressed in the report.

  • 27.
    Ahlberg, Joakim
    Swedish National Road and Transport Research Institute, Society, environment and transport, Transport economics, TEK.
    Luftfartens samhällsekonomiska marginalkostnader: delstudie inom SAMKOST2014Report (Other academic)
    Abstract [en]

    This report is a literature review on the marginal social costs of aviation, and is a sub-project to VTI’s project about updating the knowledge of the external costs of traffic (SAMKOST). The report discusses which impacts of aviation are external, and which are already internalized. It is not entirely clear which impacts that should be considered as the relevant marginal costs for aviation. For example, both congestion and accidents are seen as internalized since they are already taken care of through the air traffic control service, a service that all aircraft must use in Swedish airspace by law. Similar arguments applies to the infrastructure. The large external effect is aviation’s environmental impact. It is separated into three different categories; the impact of noise, air quality and the impact on the climate.

  • 28.
    Ahlberg, Joakim
    Swedish National Road and Transport Research Institute, Society, environment and transport, Transport economics Stockholm. Örebro universitet, Handelshögskolan vid Örebro Universitet.
    Multi-unit common value auctions: a laboratory experiment with three sealed-bid mechanisms2012Manuscript (preprint) (Other academic)
    Abstract [en]

    This study addresses a discrete common value environment with independent (one-dimensional) private signals, where the seller offers two identical units and the buyers have (flat) demand for both. Each session is conducted with2, 3 or 4 buyers. Three auction formats are used: the discriminatory, uniformand Vickrey auctions which are all subjected to a variation in the number of bidders and to repeating bid rounds on each subject. The main findings are that there are no significant differences between the uniform and the discriminatory auction in collecting revenue, while the Vickrey auction comes out as inferior. More bidders in the auction result in a greater revenue and level out the performance across the mechanisms. Demand reduction is visible in the experiment, but it is not as prominent as anticipated. Moreover, subjects come closer to equilibrium play over time. Finally, the winner’s curse is less severe than what is reported for inexperienced bidders in other studies.

  • 29.
    Ahlberg, Joakim
    Swedish National Road and Transport Research Institute, Society, environment and transport, Transport economics Stockholm. Örebro universitet, Handelshögskolan vid Örebro Universitet.
    Multi-unit common value auctions: an experimental comparison between the static and the dynamic uniform auction2012Manuscript (preprint) (Other academic)
    Abstract [en]

    It is still an open question whether the dynamic or the static format should be used in multi-unit settings, in a uniform price auction. The present study conducts an economic experiment in a common value environment, where it is found that it is more a question of whether the auctioneer wants to facilitate price discovery, and thereby lessen the otherwise pervasive overbidding, or if only the revenue is important. The experiment in the present paper provides evidence that the static format gives a significantly greater revenue than the dynamic auction, in both small and large group sizes. But a higher revenue comes at a cost; half of the auctions in the static format yield negative profits to the bidders, the winner’s curse is more severely widespread in the static auction, and only a minority of the bidders use the equilibrium bidding strategy.

  • 30.
    Ahlberg, Joakim
    Swedish National Road and Transport Research Institute, Society, environment and transport, Transport economics Stockholm. Örebro universitet, Handelshögskolan vid Örebro Universitet.
    Multi-unit common value auctions: theory and experiments2012Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Research on auctions that involve more than one identical item for sale was,almost non-existing in the 90’s, but has since then been getting increasing attention. External incentives for this research have come from the US spectrum, sales, the European 3G mobile-phone auctions,  and Internet auctions. The policy relevance and the huge amount of money involved in many of them have helped the theory and experimental research advance. But in auctions where values are equal across bidders, common value auctions, that is, when the value depends on some outside parameter, equal to all bidders, the research is still embryonic.

    This thesis contributes to the topic with three studies. The first uses a Bayesian game to model a simple multi-unit common value auction, the task being to compare equilibrium strategies and the seller’s revenue from three auction formats; the discriminatory, the uniform and the Vickrey auction. The second study conducts an economic laboratory experiment on basis of the first study. The third study comprises an experiment on the multi-unit common value uniform auction and compares the dynamic and the static environments of this format.

    The most salient result in both experiments is that subjects overbid. They are victims of the winner’s curse and bid above the expected value, thus earning a negative profit. There is some learning, but most bidders continue to earn a negative profit also in later rounds. The competitive effect when participating in an auction seems to be stronger than the rationality concerns. In the first experiment, subjects in the Vickrey auction do somewhat better in small groups than subjects in the other auction types and, in the second experiment, subjects in the dynamic auction format perform much better than subjects in the static auction format; but still, they overbid.

    Due to this overbidding, the theoretical (but not the behavioral) prediction that the dynamic auction should render more revenue than the static fails inthe second experiment. Nonetheless, the higher revenue of the static auction comes at a cost; half of the auctions yield negative profits to the bidders, and the winner’s curse is more severely widespread in this format. Besides, only a minority of the bidders use the equilibrium bidding strategy.The bottom line is that the choice between the open and sealed-bid formats may be more important than the choice of price mechanism, especially in common value settings.

    List of papers
    1. Analysis of discrete multi-unit, common value auctions: a study of three sealed-bid mechanisms
    Open this publication in new window or tab >>Analysis of discrete multi-unit, common value auctions: a study of three sealed-bid mechanisms
    2012 (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    This paper proposes a discrete bidding model for both quantities and pricing. It has a two-unit demand environment where subjects bid for contracts with an unknown redemption value, common to all bidders. Prior to bidding, the bidders receive private signals of information on the (common) value. The value and the signals are drawn from a known discrete affiliated joint distribution. The relevant task for the paper is to compare the equilibrium strategies and the seller’s revenue of three auction formats. We find that, of the three auctionformats below with two players, the discriminatory auction always gives the largest revenue to the seller; both the uniform and the Vickrey auction have zero revenue equilibrium strategies that put them further down in the revenue ranking. In equilibrium, bidders bid the same amount on both items in the discriminatory auction; a phenomenon not noted in either of the other auction formats.

    Publisher
    p. 27
    Keywords
    Economics
    National Category
    Economics
    Research subject
    SAB, Qa Economics and finance
    Identifiers
    urn:nbn:se:vti:diva-5313 (URN)
    Available from: 2013-12-03 Created: 2013-12-03 Last updated: 2016-02-04Bibliographically approved
    2. Multi-unit common value auctions: a laboratory experiment with three sealed-bid mechanisms
    Open this publication in new window or tab >>Multi-unit common value auctions: a laboratory experiment with three sealed-bid mechanisms
    2012 (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    This study addresses a discrete common value environment with independent (one-dimensional) private signals, where the seller offers two identical units and the buyers have (flat) demand for both. Each session is conducted with2, 3 or 4 buyers. Three auction formats are used: the discriminatory, uniformand Vickrey auctions which are all subjected to a variation in the number of bidders and to repeating bid rounds on each subject. The main findings are that there are no significant differences between the uniform and the discriminatory auction in collecting revenue, while the Vickrey auction comes out as inferior. More bidders in the auction result in a greater revenue and level out the performance across the mechanisms. Demand reduction is visible in the experiment, but it is not as prominent as anticipated. Moreover, subjects come closer to equilibrium play over time. Finally, the winner’s curse is less severe than what is reported for inexperienced bidders in other studies.

    Publisher
    p. 35
    Keywords
    Economics, Ekonomi
    National Category
    Economics
    Research subject
    SAB, Qa Economics and finance
    Identifiers
    urn:nbn:se:vti:diva-5314 (URN)
    Available from: 2013-12-03 Created: 2013-12-03 Last updated: 2014-06-10Bibliographically approved
    3. Multi-unit common value auctions: an experimental comparison between the static and the dynamic uniform auction
    Open this publication in new window or tab >>Multi-unit common value auctions: an experimental comparison between the static and the dynamic uniform auction
    2012 (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    It is still an open question whether the dynamic or the static format should be used in multi-unit settings, in a uniform price auction. The present study conducts an economic experiment in a common value environment, where it is found that it is more a question of whether the auctioneer wants to facilitate price discovery, and thereby lessen the otherwise pervasive overbidding, or if only the revenue is important. The experiment in the present paper provides evidence that the static format gives a significantly greater revenue than the dynamic auction, in both small and large group sizes. But a higher revenue comes at a cost; half of the auctions in the static format yield negative profits to the bidders, the winner’s curse is more severely widespread in the static auction, and only a minority of the bidders use the equilibrium bidding strategy.

    Publisher
    p. 35
    Keywords
    Economics, Ekonomi
    National Category
    Economics
    Research subject
    SAB, Qa Economics and finance
    Identifiers
    urn:nbn:se:vti:diva-5315 (URN)
    Available from: 2013-12-03 Created: 2013-12-03 Last updated: 2014-06-10Bibliographically approved
  • 31.
    Ahlberg, Joakim
    Swedish National Road and Transport Research Institute, Society, environment and transport, Transport economics Stockholm.
    Optimal taxation of intermediate goods in the presence of externalities: A survey towards the transport sector2004Report (Other academic)
    Abstract [sv]

    The paper surveys the literature on optimal taxation with emphasis on intermediate goods, or, more specific, freight (road) transport. There are two models frequently used, first, the one emanated from Diamond & Mirrlees' (1971) paper, where the production efficiency lemma made it clear that intermediate goods was not to be taxed. And, second, the Ramsey-Boiteux model where a cost-of-service regulation imposes a budget constraint for the regulated firm. In the latter model, in contrast to the first, freight transports (intermediate goods) are to be taxed in the Ramsey tradition, and thus trades the production efficiency lemma against a budget restriction. The paper also discusses welfare effects due to environmental tax reforms, with emphasis to what has become to known as the double dividend hypothesis. Finally, administrative costs in the context of optimal taxation is touched upon, a subject that is to a large degree repressed in optimal tax theory.

  • 32.
    Ahlberg, Joakim
    Swedish National Road and Transport Research Institute, Society, environment and transport, Transport economics Stockholm.
    Optimal taxation of intermediate goods in the presence of externalities: A survey towards the transport sector2006Report (Other (popular science, discussion, etc.))
    Abstract [en]

    The paper surveys the literature on optimal taxation with emphasis on intermediate goods, or, more specific, freight (road) transport. There are two models frequently used, first, the one emanated from Diamond & Mirrlees' (1971) paper, where the production efficiency lemma made it clear that intermediate goods was not to be taxed. And, second, the Ramsey-Boiteux model where a cost-of-service regulation imposes a budget constraint for the regulated firm. In the latter model, in contrast to the first, freight transports (intermediate goods) are to be taxed in the Ramsey tradition, and thus trades the production efficiency lemma against a budget restriction. The paper also discusses welfare effects due to environmental tax reforms, with emphasis to what has become to known as the double dividend hypothesis. Finally, administrative costs in the context of optimal taxation is touched upon, a subject that is to a large degree repressed in optimal tax theory.

  • 33.
    Ahlberg, Joakim
    Swedish National Road and Transport Research Institute, Society, environment and transport, Transport economics Stockholm.
    Revenues in discrete multi-unit, common value auctions: a study of three sealed-bid mechanisms2009In: Portuguese economic journal, ISSN 1617-9838, Vol. 8, no 1, p. 21p. 3-14Article in journal (Refereed)
    Abstract [en]

    We propose in this paper a discrete bidding model, both on quantities and in pricing. It has a two-unit demand environment where subjects bid for contracts with an unknown redemption value, common to all bidders. Prior to bidding, the bidders receive private signals of information on the (common) value. Both the value and the signals are drawn from a known discrete affiliated joint distribution. The relevant task for the paper is to compare equilibrium strategies and the seller's revenue between the three auction formats. We find that, among the three auction formats below with two players, the Vickrey auction always gives the most revenue to the seller, where the discriminatory auction becomes second and the uniform auction last. We also find that, in equilibrium, bidders bid the same amount on both items in the discriminatory auction; a phenomenon we do not notice in either of the other two auction formats. There, different amount of demand reduction is encountered.

  • 34.
    Ahlberg, Joakim
    et al.
    Ramböll .
    Ericson, Johan
    WSP.
    Johansson, Oskar
    Swedish National Road and Transport Research Institute, Society, environment and transport, Transport economics.
    Ridderstedt, Ivan
    Swedish National Road and Transport Research Institute, Society, environment and transport, Transport economics.
    Marginalkostnad för luftfartens infrastruktur2017Report (Other academic)
    Abstract [en]

    The main purpose of this study is to estimate the marginal costs of aviation infrastructure. But since it not exist a uniform definition of what is the cost base of the aviation infrastructure, there is also a discussion of what costs should be included. An additional purpose of the study is to relate the estimated marginal costs to today's pricing and to investigate whether aviation pays its socio-economic costs.

    Estimates of the marginal cost of utilizing (relevant) airport infrastructure and for operating airline infrastructure is being analyzed using cost data from Stockholm Arlanda Airport and the Civil Aviation Authority. The empirical approach used to analyze cost items is a regression analysis, with adjustments for month-specific variations in travel patterns, when the airport section is investigated, and taking into account regional differences for airports when investigating air traffic control in the towers.

    There are some uncertainties in the study, but in the light of this, the results indicate that the average marginal cost of the infrastructure is around SEK 13 per passenger and SEK1,168 per aircraft started. Corresponding estimation for air traffic management is also uncertain, with results indicating a marginal cost of SEK 373 per flight. Furthermore, it appears that the revenue from marginal cost-based charges could not alone finance the state aviation infrastructure.

  • 35.
    Ahlberg, Joakim
    et al.
    Swedish National Road and Transport Research Institute, Society, environment and transport, Transport economics Stockholm.
    Johansson, Anna
    Swedish National Road and Transport Research Institute, Society, environment and transport, Transport economics Stockholm.
    Etablering av konkurrerande snabbtågstrafik på Västra stambanan: översyn ur marknadens synvinkel2014Report (Other academic)
    Abstract [en]

    As of October 2010 the railway market is liberalised. As a result, other operators than SJ could apply for track capacity also for long-distance passenger services, and the timetable for 2012 was the first timetable that was affected by the liberalisation. The Swedish railway network has, by definition, capacity restrains. The Swedish Transport Administration (Trafikverket) allocates capacity among those railway traffic operators that has applied for track capacity in the annual capacity allocation process. In the capacity allocation process for the 2014 timetable, four operators applied for capacity for long-distance high-speed train traffic between Gothenburg and Stockholm. In several cases the operators applied for the same train paths, which put Trafikverket’s applying of the process, the use of coordination and prioritization criteria, to the test for the first time since the liberalisation. VTI has interviewed the three largest of the above operators to receive information about how they experienced the capacity allocation process leading to the timetable for 2014 and to get their views on the possible obstacles that may exist for establishing a new operator on the railway market. The study was commissioned by the Swedish Transport Agency as a basis for their market surveillance in the area. The operators that are challenging SJ perceive that the capacity allocation process does not meet the requirement for competitive neutrality and non-discrimination. Both operators see the need for a more transparent process, with priority criteria that provide a more predictable outcome and which is carried out by the help of computerized tools so that the process can be implemented more efficiently and provide a more effective outcome. They argue that the construction of a timetable is so complex that it is difficult to, as now being done, manually make the most effective adjustments in the timetable necessary due to competing applications. The challenging operators therefore call for a review of the process to assess in which areas it can be improved.

  • 36.
    Ahlberg, Joakim
    et al.
    Swedish National Road and Transport Research Institute, Society, environment and transport, Transport economics, TEK.
    Nilsson, Jan-Eric
    Swedish National Road and Transport Research Institute, Society, environment and transport, Transport economics, TEK.
    Ad hoc-processen: hur används ledig kapacitet i järnvägsnätet?2016Report (Other academic)
    Abstract [en]

    After the Swedish Transport Administration’s adoption of next year's timetable in mid-fall each year, starts the so-called ad hoc process, i.e. requests for train paths that can use spare capacity in the network. VTI received in September 2015 Transport Agency's mission to deepen the understanding of the ad hoc-process, This “notat” reports that assignment. In light of the description that was made, the intention was to also find the measure of the importance of this process in relation to the process leading to adopting a final schedule. It has been found that the Transport Administration’s various information management systems are not designed to enable such a description.

    Thanks to a recent statistical tool, it is possible to observe that nearly 97 percent of the passenger trains booked into the annual timetable process, also actually run. This refers to two thirds of the timetable year 2015. The aim of the Transport Agency/Traffic analysis is to, in the near future, also report similar information about freight train. Behind this figure conceals both an outflow and an inflow of traffic that will be conducted in accordance with the timetable set out in the autumn of each year. However, there is no knowledge of when these changes are implemented, which is of great importance for assessing the degree of flexibility in the ad hoc process. This situation may change as a result of the Transport Agency as of the timetable relating to 2016 for the charges to cancel the allocated capacity. The fee will be higher the closer to the scheduled departure of the train the application is withdrawn. This can help improve the flexibility in the use of the track capacity not reserved in the annual timetabling process. Another consequence may be that the information on the process will improve.

  • 37.
    Ahlin, S
    et al.
    Swedish National Road and Transport Research Institute.
    Thoren, H
    Swedish National Road and Transport Research Institute.
    Bergtekniska egenskaper hos gnejser. ( Byggnadsindustrin 1978, nr 39)1979Report (Other academic)
  • 38.
    Ahlstrand, Ingemar
    Swedish National Road and Transport Research Institute.
    Beslutsprocessen för infrastrukturella investeringar från Scanlink till KomKom1997Report (Other (popular science, discussion, etc.))
  • 39.
    Ahlström, Christer
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Human-vehicle-transport system interaction.
    Andersson, Jan
    Swedish National Road and Transport Research Institute, Traffic and road users, Human-vehicle-transport system interaction.
    Anund, Anna
    Swedish National Road and Transport Research Institute, Traffic and road users, Human-vehicle-transport system interaction.
    Börjesson, Emma
    Scania.
    Johansson, Hanna
    Scania.
    Johnsson, Johanna
    Scania.
    Detecting sleepiness by Optalert: final report2010Report (Other academic)
    Abstract [en]

    Many crashes with heavy vehicle can be attributed to driver sleepiness or driving impairment due to sleepiness, and it is important to find methods to predict those situations and counteract this problem. The Optalert fatigue management system claims to be able to detect sleepiness. The aims of this study are to (a) evaluate if Optalert can detect sleepiness equally well as other sleepiness indicators and (b) if the data patterns obtained by Optalert correlates with these other sleepiness indicators. Twelve sleep deprived truck drivers drove for about 90 minutes in an advanced moving base truck simulator. The experimental setup, including the sleep deprivation, was designed so that the drivers should become increasingly sleepier during the trial and the intention was that they should fall asleep during the experiment.

    Four different indicators of sleepiness or driving impairment due to sleepiness were used to monitor the state of the drivers; the Karolinska Sleepiness Scale (KSS), the variability in lateral position (SDLP), the blink duration and the Optalert system. The results show that all four sleepiness indicators increased with time on task. An analysis of variance revealed that the changes were significant for KSS, blink duration and the Optalert system, and a correlation analysis showed that Optalert correlated significantly with blink duration and SDLP. However, even though these correlations were significant, they were all rather low with a maximum correlation coefficient of 0.24.

    In conclusion, the Optalert system is promising and the sleepiness rating provided by the system works at least equally well as the other three sleepiness indicators. There are some practical limitations to the system; there is no reliable threshold which can be used to determine when a driver is getting too sleepy to drive (this is also the case for other available sleepiness indicators), the driver needs to be attached to the vehicle via the spectacle frames and a wire, and the quality of the eye movement recordings often deteriorated when the driver started driving the truck. Moreover, during the experiment the technical reliability was sometimes low.

  • 40.
    Ahlström, Christer
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Human Factors in the Transport System.
    Anund, Anna
    Swedish National Road and Transport Research Institute, Traffic and road users, Human Factors in the Transport System.
    Fors, Carina
    Swedish National Road and Transport Research Institute, Traffic and road users, Human Factors in the Transport System.
    Åkerstedt, Torbjörn
    Karolinska Institutet.
    Effects of the road environment on the development of driver sleepiness in young male drivers2018In: Accident Analysis and Prevention, ISSN 0001-4575, E-ISSN 1879-2057, Vol. 112, p. 127-134Article in journal (Refereed)
    Abstract [en]

    Latent driver sleepiness may in some cases be masked by for example social interaction, stress and physical activity. This short-term modulation of sleepiness may also result from environmental factors, such as when driving in stimulating environments. The aim of this study is to compare two road environments and investigate how they affect driver sleepiness. Thirty young male drivers participated in a driving simulator experiment where they drove two scenarios: a rural environment with winding roads and low traffic density, and a suburban road with higher traffic density and a more built-up roadside environment. The driving task was essentially the same in both scenarios, i.e. to stay on the road, without much interaction with other road users. A 2 x 2 design, with the conditions rural versus suburban, and daytime (full sleep) versus night-time (sleep deprived), was used. The results show that there were only minor effects of the road environment on subjective and physiological indicators of sleepiness. In contrast, there was an increase in subjective sleepiness, longer blink durations and increased EEG alpha content, both due to time on task and to night-time driving. The two road environments differed both in terms of the demand on driver action and of visual load, and the results indicate that action demand is the more important of the two factors. The notion that driver fatigue should be countered in a more stimulating visual environment such as in the city is thus more likely due to increased task demand rather than to a richer visual scenery. This should be investigated in further studies.

  • 41.
    Ahlström, Christer
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Human Factors in the Transport System.
    Anund, Anna
    Swedish National Road and Transport Research Institute, Traffic and road users, Human Factors in the Transport System.
    Fors, Carina
    Swedish National Road and Transport Research Institute, Traffic and road users, Human Factors in the Transport System.
    Åkerstedt, Torbjörn
    Stockholms Universitet.
    The effect of daylight versus darkness on driver sleepiness: A driving simulator study2017In: Journal of Sleep Research, ISSN 0962-1105, E-ISSN 1365-2869Article in journal (Refereed)
    Abstract [en]

    Driver sleepiness studies are often carried out with alert drivers during daytime and sleep-deprived drivers during night-time. This design results in a mixture of different factors (e.g. circadian effects, homeostatic effects, light conditions) that may confound the results. The aim of this study was to investigate the effect of light conditions on driver sleepiness. Thirty young male drivers (23.6 ± 1.7 years old) participated in a driving simulator experiment where they drove on a rural road. A 2 × 2 design was used with the conditions daylight versus darkness, and daytime (full sleep) versus night-time (sleep deprived). The results show that light condition had an independent effect on the sleepiness variables. The subjective sleepiness measured by Karolinska Sleepiness Scale was higher, lateral position more left-oriented, speed lower, electroencephalogram alpha and theta higher, and blink durations were longer during darkness. The number of line crossings did not change significantly with light condition. The day/night condition had profound effects on most sleepiness indicators while controlling for light condition. The number of line crossings was higher during night driving, Karolinska Sleepiness Scale was higher, blink durations were longer and speed was lower. There were no significant interactions, indicating that light conditions have an additive effect on sleepiness. In conclusion, Karolinska Sleepiness Scale and blink durations increase primarily with sleep deprivation, but also as an effect of darkness. Line crossings are mainly driven by the need for sleep and the reduced alertness at the circadian nadir. Lane position is, however, more determined by light conditions than by sleepiness.

  • 42.
    Ahlström, Christer
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Human-vehicle-transport system interaction.
    Bolling, Anne
    Swedish National Road and Transport Research Institute, Traffic and road users, Vehicle technology and simulation.
    Sörensen, Gunilla
    Swedish National Road and Transport Research Institute, Traffic and road users, Traffic safety, society and road-user.
    Eriksson, Olle
    Swedish National Road and Transport Research Institute, Infrastructure, Infrastructure maintenance.
    Andersson, Anders
    Swedish National Road and Transport Research Institute, Traffic and road users, Vehicle technology and simulation.
    Validating speed and road surface realism in VTI driving simulator III2012Report (Other academic)
    Abstract [en]

    New simulator models concerning vibration, noise and graphics have been designed and implemented in the VTI Simulator III. The objective of this study is to validate this simulator in terms of road surface realism. Twenty-four drivers participated in the study and drove the same route both in the simulator and on real roads. Three road sections ranging from very smooth to rather uneven were incorporated in the design. The comparison included the objective driving parameter speed as well as subjective parameters from questionnaires and rating scales (evenness, quietness and comfort level). A road section with five speed limit changes was of particular interest in the analyses. No statistically significant difference could be found between the simulator and the car, neither in the parameter speed (in sections with no speed limit changes) nor in the ratings evenness and quietness. Despite similar speed profiles surrounding the speed limit signs, there was a statistically significant difference between the speed in the car and in the simulator, with more rapid accelerations and decelerations in the simulator. The comfort rating was shown to be higher in the car compared to the simulator, but in both cases the general trend showed higher comfort on smoother roads. These results indicate absolute validity for the ratings evenness and quietness, and for the measure speed, and relative validity for comfort and speed surrounding speed limit signs.

  • 43.
    Ahlström, Christer
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Human-vehicle-transport system interaction.
    Dukic, Tania
    Swedish National Road and Transport Research Institute, Traffic and road users, Human-vehicle-transport system interaction.
    Comparison of eye tracking systems with one and three cameras2011In: ACM International Conference Proceeding Series, 2011Conference paper (Refereed)
    Abstract [en]

    When using eye movements to determine the state of a car driver it is important that the eye tracker is robust, unobtrusive, inexpensive and fully automatic. The objectives of this study are to compare the performance of a one-camera system with a three-camera system and to investigate if the accuracy and availability of the one-camera system is sufficient to monitor driver state. Data from 53 subjects were evaluated and the results indicate that there is not much difference between a single-camera system and a multi-camera system as long as the driver is looking straight ahead. However, with more peripheral gaze directions, the larger coverage that is provided by the additional cameras works in favour of the multi-camera system. © ACM 2010.

  • 44.
    Ahlström, Christer
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Human-vehicle-transport system interaction.
    Dukic, Tania
    Swedish National Road and Transport Research Institute, Traffic and road users, Human-vehicle-transport system interaction.
    Ivarsson, Erik
    SmartEye.
    Kircher, Albert
    Swedish National Road and Transport Research Institute.
    Rydbeck, Bosse
    SmartEye.
    Viström, Matias
    Saab Automobile.
    Performance of a one-camera and a three-camera system2010Report (Other academic)
    Abstract [en]

    Driving and operating a vehicle is to a great extent a visual task. In driver behaviour studies it is therefore important to be able to measure where the driver is looking. Today this can be done unobtrusively and remotely in real-time with camera based eye tracking. The most common remote eye tracking systems use multiple cameras in order to give satisfactory results. However, promising results using only one camera has recently emerged on the market. The main objective of this study is to compare eye tracking systems with one and three cameras, respectively, during various measurement conditions.

    A total of 53 participants were enrolled in the study. Data from the two eye trackers were acquired and analysed in terms of availability, accuracy and precision. The results indicate that both availability and accuracy are affected by many different factors. The most important factors are the number of cameras that is used and the angular distance from straight ahead. In the central region (straight ahead) both one-camera and three-camera systems have a high degree of accuracy and availability, but with increasing distance from the central region, the results deteriorate. This effect falls harder upon the one-camera system. Interestingly, there were no significant effects when wearing glasses in either availability or accuracy. There was however an interaction effect between distance and glasses.

    Advantages with a one-camera system are that it is cheaper, easier to operate and easier to install in a vehicle. A multi-camera system will, on the other hand, provide higher availability and accuracy for areas that are far from the road centre. A one-camera system is thus mostly suitable for in-vehicle applications such as systems that warn drivers for sleepiness or distraction while multi-camera solutions are preferable for research purposes.

  • 45.
    Ahlström, Christer
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Human-vehicle-transport system interaction.
    Fors, Carina
    Swedish National Road and Transport Research Institute, Traffic and road users, Human-vehicle-transport system interaction.
    Anund, Anna
    Swedish National Road and Transport Research Institute, Traffic and road users, Human-vehicle-transport system interaction.
    Hallvig, David
    Stockholms Universitet.
    Video-based observer rated sleepiness versus self-reported subjective sleepiness in real road driving2015In: European Transport Research Review, ISSN 1867-0717, E-ISSN 1866-8887, Vol. 7, no 4, article id 38Article in journal (Refereed)
    Abstract [en]

    Observer-rated sleepiness (ORS) based on video recordings of the driver’s face is often used when analysing naturalistic driving data. The aim of this study is to investigate if ORS ratings agree with subjective self-reported sleepiness (SRS).

    Forty raters assessed 54 video-clips showing drivers with varying levels of sleepiness. The video-clips were recorded during a field experiment focusing on driver sleepiness using the same cameras that are typically used in large-scale field studies. The weak results prompted a second test. Ten human factors researchers made pairwise comparisons of videos showing the same four participants in an alert versus a very sleepy condition. The task was simply to select the video-clip where the driver was sleepy.

    The overall average percentage of video segments where ORS and SRS matched was 41 % in Test 1. ORS 0 (alert) and ORS 2 (very sleepy) were easier to score than ORS 1 and it was slightly harder to rate night-time drives. Inter-rater agreement was low, with average Pearson’s r correlations of 0.19 and Krippendorff’s alpha of 0.15. In Test 2, the average Pearson’s r correlations was 0.35 and Krippendorff’s alpha was 0.62. The correspondence between ORS and SRS showed an agreement of 35 %.

    The results indicate that ORS ratings based on real road video recordings correspond poorly with SRS and have low inter-rater agreement. Further research is necessary in order to further evaluate the usefulness of ORS as a measure of sleepiness.

  • 46.
    Ahlström, Christer
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Human-vehicle-transport system interaction.
    Fors, Carina
    Swedish National Road and Transport Research Institute, Traffic and road users, Human-vehicle-transport system interaction.
    Forward, Sonja
    Swedish National Road and Transport Research Institute, Society, environment and transport, Mobility, actors and planning processes.
    Gregersen, Nils Petter
    Swedish National Road and Transport Research Institute, Society, environment and transport, Mobility, actors and planning processes.
    Hjälmdahl, Magnus
    Swedish National Road and Transport Research Institute, Traffic and road users, Human-vehicle-transport system interaction.
    Jansson, Jonas
    Swedish National Road and Transport Research Institute, Traffic and road users.
    Kircher, Katja
    Swedish National Road and Transport Research Institute, Traffic and road users, Human-vehicle-transport system interaction.
    Lindberg, Gunnar
    Swedish National Road and Transport Research Institute, Society, environment and transport, Transport economics Stockholm.
    Nilsson, Lena
    Swedish National Road and Transport Research Institute, Traffic and road users.
    Patten, Christopher
    Swedish National Road and Transport Research Institute, Traffic and road users, Human-vehicle-transport system interaction.
    Dangerous use of mobile phones and other communication devices while driving: A toolbox of counter-measures2013In: Proceedings of the 16th International Conference Road Safety on Four Continents: Beijing, China. 15-17 May 2013, Linköping: Statens väg- och transportforskningsinstitut, 2013Conference paper (Other academic)
    Abstract [en]

    The use of mobile phone and similar devices while driving has been a topic of discussion and research for several years. It is now an established fact that driving performance is deteriorated due to distraction but no clear conclusions can yet be drawn concerning influence on crash rates. Better studies on this relationship is needed. Most countries in Europe and many countries elsewhere have introduced different types of bans for handheld devices. Sweden has, however, no such bans. VTI was commissioned by the Swedish Government to outline possible means to reduce the dangerous usage of mobile phones and other communication devices while driving as alternatives to banning. This task was a result of a previous VTI-state-of-the-art review of research on mobile phone and other communication device usage while driving. One of the findings in the review was that bans on handheld phones did not appear to reduce the number of crashes.

    Eighteen different countermeasures in three main areas were suggested. (1) Technical solutions such as countermeasures directed towards the infrastructure, the vehicle and the communication device. (2) Education and information, describing different ways to increase knowledge and understanding among stakeholders and different driver categories. (3) Different possibilities for how society, industry and organisations can influence the behaviour of individuals, via policies, rules, recommendations and incentives. Our conclusion is that a combination of different countermeasures is needed – where education and information to the drivers are combined with support and incentives for a safe usage of different communication devices.

  • 47.
    Ahlström, Christer
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Trafikanttillstånd, TIL.
    Ihlström, Jonas
    Swedish National Road and Transport Research Institute, Traffic and road users, Trafikanttillstånd, TIL.
    Kircher, Katja
    Swedish National Road and Transport Research Institute, Traffic and road users, Trafikanttillstånd, TIL.
    Förares användning av kommunikationsutrustning under färd: Del 1: Enkätstudie. Del 2: Användning enligt objektiv mätning2017Report (Other academic)
    Abstract [sv]

    Av resultaten från denna enkät är något av det mest tydliga att saker som funnits i en bil en längre tid, exempelvis att ställa in radio, använda navigationsutrustning och prata i telefon, görs i betydligt högre utsträckning än nyare saker som att skicka meddelanden, surfa på internet eller spela spel. Överlag tycks det vara låg acceptans för de nyare företeelserna och en stor andel av urvalet tycker att det är felaktigt eller olämpligt att hålla på med dessa aktiviteter. Att prata i telefon med handsfree tycks uppfattas av många som säkrare och mer lämpligt än att inte använda det. Detta avspeglas även i inställning till införandet av förbud, där en relativt stor andel accepterar att det ska vara lagligt att använda handsfreefunktioner men att annan användning av kommunikationsutrustning borde förbjudas.

    I den andra delen genomfördes en mätning av mobilanvändning under färd genom installerande tav en mobilapp. Den genomförda undersökningen är den första av sitt slag åtminstone i Sverige, så att den, trots vissa brister och begränsningar, kan leverera information som hittills har varit okänt. I detta del diskuteras resultaten, även i förhållande till enkätsvaren, följt av en reflektion över metoden och möjliga förbättringar, som är önskvärda inför en fortsättningsstudie.

  • 48.
    Ahlström, Christer
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Trafikanttillstånd, TIL.
    Jansson, Sabina
    Linköpings Universitet.
    Anund, Anna
    Swedish National Road and Transport Research Institute, Traffic and road users, Trafikanttillstånd, TIL.
    Local changes in the wake electroencephalogram precedes lane departures2017In: Journal of Sleep Research, ISSN 0962-1105, E-ISSN 1365-2869Article in journal (Refereed)
    Abstract [en]

    The objective of this exploratory study is to investigate if lane departures are associated with local sleep, measured via source-localized electroencephalography (EEG) theta power in the 5-9 Hz frequency range. Thirty participants drove in an advanced driving simulator, resulting in 135 lane departures at high levels of self-reported sleepiness. These lane departures were compared to matching non-departures at the same sleepiness level within the same individual. There was no correspondence between lane departures and global theta activity. However, at the local level an increased risk for lane departures was associated with increased theta content in brain regions related to motor function.

  • 49.
    Ahlström, Christer
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Human Factors in the Transport System.
    Kircher, Katja
    Swedish National Road and Transport Research Institute, Traffic and road users, Human Factors in the Transport System. Linköpings Universitet.
    A Generalized Method to Extract Visual Time-Sharing Sequences From Naturalistic Driving Data2017In: IEEE transactions on intelligent transportation systems (Print), ISSN 1524-9050, E-ISSN 1558-0016, Vol. 18, no 11, p. 2929-2938Article in journal (Refereed)
    Abstract [en]

    Indicators based on visual time-sharing have been used to investigate drivers' visual behaviour during additional task execution. However, visual time-sharing analyses have been restricted to additional tasks with well-defined temporal start and end points and a dedicated visual target area. We introduce a method to automatically extract visual time-sharing sequences directly from eye tracking data. This facilitates investigations of systems, providing continuous information without well-defined start and end points. Furthermore, it becomes possible to investigate time-sharing behavior with other types of glance targets such as the mirrors. Time-sharing sequences are here extracted based on between-glance durations. If glances to a particular target are separated by less than a time-based threshold value, we assume that they belong to the same information intake event. Our results indicate that a 4-s threshold is appropriate. Examples derived from 12 drivers (about 100 hours of eye tracking data), collected in an on-road investigation of an in-vehicle information system, are provided to illustrate sequence-based analyses. This includes the possibility to investigate human-machine interface designs based on the number of glances in the extracted sequences, and to increase the legibility of transition matrices by deriving them from time-sharing sequences instead of single glances. More object-oriented glance behavior analyses, based on additional sensor and information fusion, are identified as the next future step. This would enable automated extraction of time-sharing sequences not only for targets fixed in the vehicle's coordinate system, but also for environmental and traffic targets that move independently of the driver's vehicle.

  • 50.
    Ahlström, Christer
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Trafikanttillstånd, TIL.
    Kircher, Katja
    Swedish National Road and Transport Research Institute, Traffic and road users, Trafikanttillstånd, TIL. Linköping University.
    Changes in glance behaviour when using a visual eco-driving system: A field study2017In: Applied Ergonomics, ISSN 0003-6870, E-ISSN 1872-9126, Vol. 58, p. 414-423Article in journal (Refereed)
    Abstract [en]

    While in-vehicle eco-driving support systems have the potential to reduce greenhouse gas emissions and save fuel, they may also distract drivers, especially if the system makes use of a visual interface. The objective of this study is to investigate the visual behaviour of drivers interacting with such a system, implemented on a five-inch screen mounted above the middle console. Ten drivers participated in a real-world, on-road driving study where they drove a route nine times (2 pre-baseline drives, 5 treatment drives, 2 post-baseline drives). The route was 96 km long and consisted of rural roads, urban roads and a dual-lane motorway.

    The results show that drivers look at the system for 5–8% of the time, depending on road type, with a glance duration of about 0.6 s, and with 0.05% long glances (>2s) per kilometre. These figures are comparable to what was found for glances to the speedometer in this study. Glance behaviour away from the windscreen is slightly increased in treatment as compared to pre- and post-baseline, mirror glances decreased in treatment and post-baseline compared to pre-baseline, and speedometer glances increased compared to pre-baseline. The eco-driving support system provided continuous information interspersed with additional advice pop-ups (announced by a beep) and feedback pop-ups (no auditory cue). About 20% of sound initiated advice pop-ups were disregarded, and the remaining cases were usually looked at within the first two seconds. About 40% of the feedback pop-ups were disregarded. The amount of glances to the system immediately before the onset of a pop-up was clearly higher for feedback than for advice.

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