| 1. |
- Bakker, Bram, et al.
(författare)
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A Multi-Stage, Multi-Feature Machine Learning Approach to Detect Driver Sleepiness in Naturalistic Road Driving Conditions
- 2022
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Ingår i: IEEE transactions on intelligent transportation systems (Print). - : IEEE. - 1524-9050 .- 1558-0016. ; 23:5, s. 4791-4800
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Tidskriftsartikel (refereegranskat)abstract
- Driver fatigue is a contributing factor in about 20% of all fatal road crashes worldwide. Countermeasures are urgently needed and one of the most promising and currently available approaches for that are in-vehicle systems for driver fatigue detection. The main objective of this paper is to present a video-based driver sleepiness detection system set up as a two-stage model with (1) a generic deep feature extraction module combined with (2) a personalised sleepiness detection module. The approach was designed and evaluated using data from 13 drivers, collected during naturalistic driving conditions on a motorway in Sweden. Each driver performed one 90-minute driving session during daytime (low sleepiness condition) and one session during night-time (high sleepiness condition). The sleepiness detection model outputs a continuous output representing the Karolinska Sleepiness Scale (KSS) scale from 1-9 or a binary decision as alert (defined as KSS 1-6) or sleepy (defined as KSS 7-9). Continuous output modelling resulted in a mean absolute error (MAE) of 0.54 KSS units. Binary classification of alert or sleepy showed an accuracy of 92% (sensitivity = 91.7%, specificity = 92.3%, F1 score = 90.4%). Without personalisation, the corresponding accuracy was 72%, while a standard fatigue detection PERCLOS-based baseline method reached an accuracy of 68% on the same dataset. The developed real-time sleepiness detection model can be used in the management of sleepiness/fatigue by detecting precursors of severe fatigue, and ultimately reduce sleepiness-related road crashes by alerting drivers before high levels of fatigue are reached.
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| 2. |
- Finnsgård, Christian, 1974, et al.
(författare)
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Swedish shippers’ strategies for coping with slow-steaming in deep sea container shipping
- 2018
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Ingår i: Journal of Shipping and Trade. - : Springer. - 2364-4575. ; 3:8
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Tidskriftsartikel (refereegranskat)abstract
- When container shipping lines experience over-capacity and high fuel costs, they typically respond by decreasing sailing speeds and, consequently, increasing transport time. Most of the literature on this phenomenon, often referred to as slow-steaming, takes the perspective of the shipping lines addressing technical, operational and financial effects, or a society perspective focusing on lower emissions and energy use. Few studies investigate the effects on the demand side of the market for container liner shipping. Hence, the aim of this study is to elaborate on the logistics consequences of slow-steaming, particularly the strategies that Swedish shippers purchasing deep sea container transport services employ to mitigate the effects of slow-steaming. Workshops and semi-structured interviews revealed that shippers felt they had little or no impact on sailing schedules and were more or less subject to container shipping lines’ decisions. The effects of slow-steaming were obviously most severe for firms with complex supply chains, where intermediate products are sent back and forth between production stages on different continents. The shippers developed a set of strategies to cope with the low punctuality of containerised shipping, and these were categorised in the domains of transfer-the-problem, transport, sourcing and distribution, logistics and manufacturing, and product design. All firms applied changes in the transport domain, although the lack of service segmentation limited the effects of the strategy. Most measures were applied by two firms, whereas only one firm changed the product design.
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| 3. |
- Bhatti, Harrison John, et al.
(författare)
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Multidimensional Readiness Index for Electrification of Transportation System in China, Norway, and Sweden
- 2022
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The main objective of this paper is to develop a readiness index model that can serve as an analytical tool for exploring the achievements of electrification of transportation systems. We have applied this readiness index model to evaluate the readiness positioning of China, Norway, and Sweden towards transport electrification. We have chosen these three countries as they represent diversity among countries that are in the process of adopting electrified transport system solutions. Our developed readiness index model has four key dimensions, technological readiness, political readiness, societal readiness, and economic readiness. The embeddedness of all four dimensions in one model provides a multi-perspective way of analyzing and evaluating the readiness levels of countries moving towards transforming the transportation system. Therefore, we named the model a“multidimensional readiness index.”Our main conclusions are that the political processes and political decisiveness involved are the most important factors followed by the societal needs and economic ability, with the current technology available as the fourth. Without the participation of dedicated and determined political decision-makers being involved, the other three factors are challenging to obtain. Political decision-makers need to facilitate the use of economic means to support the transformation in the society and affected industries to balance the initial economic disadvantages of the electrically-powered systems until they pass the cost disadvantage turning point. The development of the relevant technology is no longer a great barrier as it was at the beginning of this transformation, about 20 years ago. The technology for electrically powered transportation systems and devices is widely available now, although it is continuously evolving and being improved. Associated industries cannot be expected to initiate, finance, take the risk, and take the lead in this global societal transformation without clear and strong political support.Based on our multidimensional readiness index analysis, China is being positioned as the leading country in the world in the electrification of its transportation systems. This is mainly so because of the strong technology advancements, control of the entire value chain of research, development (R&D), and manufacturing of EVs, strong government decisiveness, and execution power in developing and implementing favorable electric vehicle (EV) policies. The willingness of China’s public sector to take the lead and their citizen’s support to adopt clean technology are additional factors facilitating this advancement. Norway has rapidly become one of the newcomers in electrification with large numbers of registered electric vehicles, despite lacking manufacturing industries of electric vehicles. Sweden is a rapidly developing country in the electrification of transport, with three vehicle manufacturers introducing EVs in 2021. The government has been committed to building demonstration sites for electric roads systems for more than ten years. Sweden is also working on establishing battery manufacturing facilities dedicated to the needs of electrified transportation equipment and systems.
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| 4. |
- Bianchi Piccinini, Giulio, 1982, et al.
(författare)
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How Do Drivers Respond to Silent Automation Failures? Driving Simulator Study and Comparison of Computational Driver Braking Models
- 2020
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Ingår i: Human Factors. - : SAGE Publications. - 1547-8181 .- 0018-7208. ; 62:7, s. 1212-1229
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Tidskriftsartikel (refereegranskat)abstract
- Objective: This paper aims to describe and test novel computational driver models, predicting drivers’ brake reaction times (BRTs) to different levels of lead vehicle braking, during driving with cruise control (CC) and during silent failures of adaptive cruise control (ACC). Background: Validated computational models predicting BRTs to silent failures of automation are lacking but are important for assessing the safety benefits of automated driving. Method: Two alternative models of driver response to silent ACC failures are proposed: a looming prediction model, assuming that drivers embody a generative model of ACC, and a lower gain model, assuming that drivers’ arousal decreases due to monitoring of the automated system. Predictions of BRTs issued by the models were tested using a driving simulator study. Results: The driving simulator study confirmed the predictions of the models: (a) BRTs were significantly shorter with an increase in kinematic criticality, both during driving with CC and during driving with ACC; (b) BRTs were significantly delayed when driving with ACC compared with driving with CC. However, the predicted BRTs were longer than the ones observed, entailing a fitting of the models to the data from the study. Conclusion: Both the looming prediction model and the lower gain model predict well the BRTs for the ACC driving condition. However, the looming prediction model has the advantage of being able to predict average BRTs using the exact same parameters as the model fitted to the CC driving data. Application: Knowledge resulting from this research can be helpful for assessing the safety benefits of automated driving.
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| 5. |
- Trosvik, Lina, 1991-, et al.
(författare)
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A meta-evaluation of climate policy evaluations : findings from the freight transport sector
- 2023
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Ingår i: Transport reviews. - : Routledge. - 0144-1647 .- 1464-5327. ; 43:5, s. 867-887
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Tidskriftsartikel (refereegranskat)abstract
- Knowledge about how implemented policy instruments have performed is important for designing effective and efficient policy instruments that contribute to reductions of greenhouse gas emissions. This paper carries out a meta-evaluation of ex-post evaluations of climate policy instruments in the freight transport sector. By analysing the outcomes and quality of evaluations, the aim is to identify whether estimated effects of policy instruments can be compared between evaluations and if the results are appropriate to use for evidence-based decision making. To analyse these aspects, commonly applied evaluation criteria are assessed and classified according to an assessment scale. We confirm that few ex-post evaluations are carried out and that there is a gap between evaluation theory and how ex-post policy evaluations are performed in practice, where evaluation criteria recommended in policy evaluation guidelines are found to often be neglected in evaluations. The result is a lack of systematic climate policy evaluation which hinders reliable conclusions about the effect of policy instruments. There is a need for more systematic monitoring and evaluation of implemented policy instruments and we suggest that evidence-based decision making can be improved by adjusting current policy evaluation guidelines and by introducing an evaluation obligation.
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| 6. |
- Isaksson, Karolina, et al.
(författare)
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Layering and parallel policy making : Complementary concepts for understanding implementation challenges related to sustainable mobility
- 2017
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Ingår i: Transport Policy. - : Elsevier BV. - 0967-070X .- 1879-310X. ; 53, s. 50-57
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Tidskriftsartikel (refereegranskat)abstract
- This paper is focused on implementation challenges related to the integration of sustainable mobility in strategic local/regional land use and transport planning. The work was based on a case study of Stockholm, Sweden, focusing on four current plans and strategies of key importance for sustainable mobility. We identify and discuss implementation challenges related to sustainable mobility using a theoretical framework from the policy integration literature, with a focus on the dimensions of “layering”, “drift” and “exhaustion” (Rayner & Howlett 2009).The empirical analysis led us to identify a complementary dimension which we call ‘Parallel policy making’. The parallel policy making reflects a fundamental lack of integration of sustainable mobility in policies and plans of strategic importance, which hinders effective policy integration. Altogether, we conclude that a better insight into the practice of parallel policy making is crucial for development of more effective implementation strategies for sustainable mobility in Stockholm and elsewhere.
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| 7. |
- Ryan, Jean
(författare)
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Towards a capability approach to mobility : An analysis of disparities in mobility opportunities among older people
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Older people represent a greater proportion of the population than ever before. In Sweden, one in five is now aged 65 and above, and more than one in seven is aged 65-79. This demographic change has challenged and will challenge society, presenting sizeable tasks for the transport sector. These challenges have forced and will force us to question the ways in which we approach and tackle the policy, planning, design and provision of services for an expanding and ever-varying proportion of older people and a changing demographic composition. The focus for this thesis is on those aged 65-79. This age group represents those who are in the young-old life stage, or what can be described as the earlier stages of later life. This age range signifies the time during which most people transition from working life to retirement, adjusting to a different set of financial circumstances, a different set of daily activities and often, deteriorating health. Several studies have shown that, as people age, they tend to change the ways in which they travel. In the Nordic context in particular, there is a long history and large inventory of research concerning the travel of older people. However, few have approached such issues from a transport equity perspective – a perspective inherent in this thesis.The results from this thesis highlight the differences in potential mobility among the young-old living in Sweden’s large metropolitan regions. The methods used complement one another, and uncover concerns and connections which may have been hidden had just one type of method been used. The dissatisfaction and limitations that can arise from having insufficient modal options in later life are highlighted. Combining and coordinating transport services and the location and provision of other important services in an integrated manner could effect change with respect to the capability to carry out everyday activities of value for this age group.
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| 8. |
- Sandin, Jesper, 1975-, et al.
(författare)
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A Lane-Change Gap Acceptance Scenario Developed for Heavy Vehicle Active Safety Assessment : A Driving Simulator Study
- 2015
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Ingår i: Proceedings of the 3rd International Symposium on Future Active Safety Technology Towards zero traffic accidents, 2015. ; , s. 537-543
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Konferensbidrag (refereegranskat)abstract
- The aims of this study were to develop a lane-change scenario for driving simulators in order to analyse the characteristics of lane-change manoeuvres performed with heavy vehicles. The scenario was set up based on information from lane-change accidents and on-road lane-change observations. The gap acceptance scenario consisted of two consecutive lane changes were the intention was to study truck drivers’ accepted gap between two vehicles in the adjacent right lane, at the initiation of each lane change. An experiment was conducted with 18 truck drivers in a full-motion driving simulator with implemented high fidelity models of an 80tonnes and 32m long vehicle combination and a 40tonnes and 22m tractor semi-trailer. The results showed no statistically significant difference in the accepted gaps to the lead and lag vehicles in the target lane. For both heavy vehicles, the overall average lead gap and lag gap was estimated to 0.85s and 0.83s respectively, at the average velocity of 17.3m/s. The difference in lane-change duration for the two vehicles was statistically significant and estimated to an average of 8.7s for the tractor semi-trailer, and 10.5s for the A-double. The conclusion from the present study is that the drivers performed the lane changes equally well with the tractor semi-trailer and the long vehicle combination. There were no major differences between the manoeuvres other than the duration times, which can be justified by the difference in vehicle length. Future studies are able to use this scenario as a non-critical reference to more critical events in the development and assessment of active safety functionality and automated driving systems.
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| 9. |
- Praetorius, Gesa, 1980-, et al.
(författare)
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Learning lessons in resilient traffic management : A cross-domain study of Vessel Traffic Service and Air Traffic Control
- 2012
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Ingår i: Human Factors : a view from an integrative perspective. - Groningen : HFES Europe Chapter. - 9780945289449 ; , s. 277-287
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Konferensbidrag (refereegranskat)abstract
- Although younger than the maritime domain, aviation has had a huge impact on the system design and development within shipping. Stakeholders often look towards aviation to make shipping, and the way that traffic is handled and organised, safer, more efficient and more effective. Although legally not the same, Vessel Traffic Service (VTS) is frequently compared to Air Traffic Control (ATC). In this article the area of traffic management within the maritime and aviation domains is addressed from a Resilience Engineering perspective. Focus is placed on the arrival part of a mission. The comparison is based on information collected during two study visits at VTS centres and one study visit at an ATC centre. The two organisations are described with the help of the Resilient Engineering capabilities: to respond, to monitor, to anticipate, and to learn. Furthermore, it is discussed how VTS and ATC adapt to cope with the complexity encountered during daily work.
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| 10. |
- Andersson-Sköld, Yvonne, 1957-, et al.
(författare)
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Development of the SUNRA Tool to Improve Regional and Local Sustainability of the Transportation Sector
- 2022
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Ingår i: Sustainability. - : MDPI AG. - 2071-1050. ; 14:18, s. 11275-
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Tidskriftsartikel (refereegranskat)abstract
- To fulfil the global sustainable development goals (SDGs), achieving sustainable development is becoming urgent, not least in the transportation sector. In response to this, the sustainability framework Sustainability National Road Administrations (SUNRA) was developed to contribute to improving the sustainability performance of national road administrations across Europe. In the present study, the framework has been tested, applied and further developed to be applicable for target setting and follow-up at the project level at both the Swedish Transport Administration (STA) and at municipal levels. The aim was a framework relevant for investment, re-investments, maintenance and operation projects and also to make it more user applicable. The study also investigated how the framework can contribute to sustainability, identified drivers and barriers for applying the framework and examined whether the framework can be applied and adapted to projects of different complexities. The adaptations and developments were done in collaboration between researchers and practitioners. The results show that the framework could easily be used and adapted for investment, re-investment, maintenance and operation projects in the planning stage, as well as for small municipal establishments, construction or reconstruction of residential areas and frequent maintenance. The framework contributes to increased awareness on sustainability, and it provides a common structure and transparency on how infrastructure project goals/targets are set and fulfilled. The framework can also be applied to follow the fulfilment of the goals/targets and thereby adapt the project to better fulfil the goals. Identified barriers include the lack of obligations and lack of experience in using sustainability frameworks.
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