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  • 1.
    Ahlström, Christer
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Human-vehicle-transport system interaction.
    Kircher, Katja
    Swedish National Road and Transport Research Institute, Traffic and road users, Human-vehicle-transport system interaction.
    Thorslund, Birgitta
    Swedish National Road and Transport Research Institute, Traffic and road users, Human-vehicle-transport system interaction.
    Adell, Emeli
    Trivector Traffic.
    Bicyclists’ visual strategies when conducting self-paced vs. system-paced smartphone tasks in traffic2015In: Transportation Research Part F: Traffic Psychology and Behaviour, ISSN 1369-8478, E-ISSN 1873-5517, Vol. 41, p. 204-216Article in journal (Refereed)
    Abstract [en]

    Visual distraction among cyclists interacting with their mobile phones is a growing concern. Yet, very little research has actually investigated how cyclists apply visual strategies and adapt task execution depending on the traffic situation. The aim of this study is to investigate visual behaviour of cyclists when conducting self-paced (initiated by the cyclist) vs. system-paced (initiated by somebody else) smartphone tasks in traffic. Twenty-two cyclists completed a track in real traffic while listening to music, receiving and making calls, receiving and sending text messages, and searching for information on the internet. The route and the types of tasks were controlled, but the cyclists could choose rather freely when and where along the route to carry out the tasks, thus providing semi-naturalistic data on compensatory behaviour. The results show that the baseline and music conditions were similar in terms of visual behaviour. When interacting with the phone, it was found that glances towards the phone mostly came at the expense of glances towards traffic irrelevant gaze targets and also led to shortened glance durations to traffic relevant gaze targets, while maintaining the number of glances. This indicates that visual “spare capacity” is used for the execution of the telephone tasks. The task type influenced the overall task duration and the overall glance intensity towards the phone, but not the mean nor maximum duration of individual glances. Task pacing was the factor that influenced visual behaviour the most, with longer mean and maximum glance durations for self-paced tasks. In conclusion, the cyclists used visual strategies to integrate the handling of mobile phones into their cycling behaviour. Glances directed towards the phone did not lead to traffic relevant gaze targets being missed. In system-paced scenarios, the cyclists checked the traffic more frequently and intensively than in self-paced tasks. This leads to the assumption that cyclists prepare for self-initiated tasks by for example choosing a suitable location. Future research should investigate whether these strategies also exists amongst drivers and other road user groups.

  • 2.
    Andersson, Jan
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users.
    Björklund, Gunilla
    Swedish National Road and Transport Research Institute, Traffic and road users, Driver and vehicle.
    Wallén Warner, Henriette
    Swedish National Road and Transport Research Institute, Traffic and road users, Driver and vehicle.
    Lättman, Katrin
    SAMOT/CTF, Karlstad University, Sweden.
    Adell, Emeli
    Trivector, Sweden.
    The complexity of changes in modal choice: A quasi-experimental study2023In: Transportation Research Part F: Traffic Psychology and Behaviour, ISSN 1369-8478, E-ISSN 1873-5517, Vol. 96, no July, p. 36-47Article in journal (Refereed)
    Abstract [en]

    Background: Changes in modal choice is argued to be one way to reduce the emission of greenhouse gases. Increasing modal choices in favour of more environmentally friendly travel modes requires a better understanding of how these choices are actually made. The first aim of this study is therefore to examine how modal choice is related to subjective experiences as perceived accessibility, perceived satisfaction , habit, both before , after an intervention promoting public transport. The second aim is to examine how modal choice is affected by the intervention. Finally, the third aim is to examine how subjective experiences as perceived accessibility, perceived satisfaction, and habit are affected by the intervention.

    Method: The design used is a before-and after-study with free public travel passes as the intervention (30-or 14-days free travel pass). Altogether, 52 travelers - distributed on two intervention groups and one control group - participated in the study. The 30-days free travel pass group constitutes 18 participants, the 14-days free travel pass group constitutes 19 participants while the control group constitutes 15 participants. During the before -period the participants were asked to register their modal choice using a digitalized application downloaded on their smart phones (the TravelVu app), to complete a short app-based questionnaire, and a web-based questionnaire. During the after-period, they were once again asked to register their modal choice and to complete a web-based questionnaire. All data collected were analyzed by variance or correlation analyses using the change between before-and after period as the dependent variable.

    Conclusion: The intervention did not affect the modal choice or the subjective experiences. Over time, the participants did however increase their use of public transport and their cognitive evaluation of their everyday travel overall, while they decreased their use of car and became less reflective and less interested in trying out new alternative travel modes. These changes might be attributed to their participation in the present study.

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  • 3.
    Aramrattana, Maytheewat
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Driving Simulation and Visualization.
    Andersson, Anders
    Swedish National Road and Transport Research Institute, Traffic and road users, Driving Simulation and Visualization.
    Reichenberg, Frida
    RISE.
    Mellegård, Niklas
    RISE.
    Burden, Håkan
    RISE.
    Testing cooperative intelligent transport systems in distributed simulators2019In: Transportation Research Part F: Traffic Psychology and Behaviour, ISSN 1369-8478, E-ISSN 1873-5517, Vol. 65, p. 206-216Article in journal (Refereed)
    Abstract [en]

    Simulation is often used as a technique to test and evaluate systems, as it provides a cost-efficient and safe alternative for testing and evaluation. A combination of simulators can be used to create high-fidelity and realistic test scenarios, especially when the systems-under-test are complex. An example of such complex systems is Cooperative Intelligent Transport Systems (C-ITS), which include many actors that are connected to each other via wireless communication in order to interact and cooperate. The majority of the actors in the systems are vehicles equipped with wireless communication modules, which can range from fully autonomous vehicles to manually driven vehicles. In order to test and evaluate C-ITS, this paper presents a distributed simulation framework that consists of (a) a moving base driving simulator; (b) a real-time vehicle simulator; and (c) network and traffic simulators. We present our approach for connecting and co-simulating the simulators. We report on limitation and performance that this simulation framework can achieve. Lastly, we discuss potential benefits and feasibility of using the simulation framework for testing of C-ITS.

  • 4.
    Aramrattana, Maytheewat
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Körsimulering och visualisering, SIM. Högskolan i Halmstad.
    Larsson, Tony
    Högskolan i Halmstad.
    Jansson, Jonas
    Swedish National Road and Transport Research Institute, Traffic and road users.
    Nåbo, Arne
    Swedish National Road and Transport Research Institute, Traffic and road users, Körsimulering och visualisering, SIM.
    A simulation framework for cooperative intelligent transport systems testing and evaluation2017In: Transportation Research Part F: Traffic Psychology and Behaviour, ISSN 1369-8478, E-ISSN 1873-5517Article in journal (Refereed)
    Abstract [en]

    Connected and automated driving in the context of cooperative intelligent transport systems (C-ITS) is an emerging area in transport systems research. Interaction and cooperation between actors in transport systems are now enabled by the connectivity by means of vehicle-to-vehicle and vehicle-to-infrastructure (V2X) communication. To ensure the goals of C-ITS, which are safer and more efficient transport systems, testing and evaluation are required before deployment of C-ITS applications. Therefore, this paper presents a simulation framework-consisting of driving-, traffic-, and network-simulators-for testing and evaluation of C-ITS applications. Examples of cooperative adaptive cruise control (CACC) applications are presented, and are used as test cases for the simulation framework as well as to elaborate on potential use cases of it. Challenges from combining the simulators into one framework, and limitations are reported and discussed. Finally, the paper concludes with future development directions, and applications of the simulation framework in testing and evaluation of C-ITS.

  • 5.
    Aramrattana, Maytheewat
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Driving Simulation and Visualization. Högskolan i Halmstad.
    Larsson, Tony
    Högskolan i Halmstad.
    Jansson, Jonas
    Swedish National Road and Transport Research Institute, Traffic and road users.
    Nåbo, Arne
    Swedish National Road and Transport Research Institute, Traffic and road users, Driving Simulation and Visualization.
    A simulation framework for cooperative intelligent transport systems testing and evaluation2017In: Transportation Research Part F: Traffic Psychology and Behaviour, ISSN 1369-8478, E-ISSN 1873-5517Article in journal (Refereed)
    Abstract [en]

    Connected and automated driving in the context of cooperative intelligent transport systems (C-ITS) is an emerging area in transport systems research. Interaction and cooperation between actors in transport systems are now enabled by the connectivity by means of vehicle-to-vehicle and vehicle-to-infrastructure (V2X) communication. To ensure the goals of C-ITS, which are safer and more efficient transport systems, testing and evaluation are required before deployment of C-ITS applications. Therefore, this paper presents a simulation framework—consisting of driving-, traffic-, and network-simulators—for testing and evaluation of C-ITS applications. Examples of cooperative adaptive cruise control (CACC) applications are presented, and are used as test cases for the simulation framework as well as to elaborate on potential use cases of it. Challenges from combining the simulators into one framework, and limitations are reported and discussed. Finally, the paper concludes with future development directions, and applications of the simulation framework in testing and evaluation of C-ITS. © 2017 Elsevier Ltd. All rights reserved.

  • 6.
    Bagdadi, Omar
    Swedish National Road and Transport Research Institute, Traffic and road users, Human-vehicle-transport system interaction.
    Assessing safety critical braking events in naturalistic driving studies2012In: Transportation Research Part F: Traffic Psychology and Behaviour, ISSN 1369-8478, E-ISSN 1873-5517, Vol. 16, p. 16p. 117-126Article in journal (Refereed)
    Abstract [en]

    Naturalistic driving studies permit the study of driving behaviour during every day driving. Such studies have a long duration and rare events such as near-crashes and even crashes do occur during the period of the study. This fact gives an opportunity to study events that are otherwise difficult to find. However, the vast amount of data recorded within these naturalistic driving studies demands a huge amount of manual work to identify hazardous situations. This paper concerns the development and validation of a new method, based on critical jerk, to identify safety critical braking events during car driving. The method was compared with one of today's most used method, which is based on the longitudinal acceleration measure. Both methods were applied on near-crash data from the 100-car naturalistic driving study previously carried out by the Virginia Tech Transportation Institute (VTTI). The data included 637 near-crashes. The results from the analyses showed that the critical jerk method performed approximately 1.6 times higher overall success rate than the method based on the longitudinal acceleration measure. In addition, a positive correlation was found between driver's safety critical braking event and crash involvement. The conclusion is that the critical jerk method is capable of detecting safety critical braking events and may also be used for assessing high risk drivers.

  • 7.
    Bazilinskyy, Pavlo
    et al.
    Delft University of Technology.
    Petermeijer, Sebastiaan M.
    Delft University of Technology.
    Petrovych, Veronika
    Swedish National Road and Transport Research Institute, Traffic and road users, Driver and vehicle.
    Dodou, Dimitra
    Delft University of Technology.
    de Winter, Joost C. F.
    Delft University of Technology.
    Take-over requests in highly automated driving: A crowdsourcing survey on auditory, vibrotactile, and visual displays2018In: Transportation Research Part F: Traffic Psychology and Behaviour, ISSN 1369-8478, E-ISSN 1873-5517, Vol. 56, p. 82-98Article in journal (Refereed)
    Abstract [en]

    An important research question in the domain of highly automated driving is how to aid drivers in transitions between manual and automated control. Until highly automated cars are available, knowledge on this topic has to be obtained via simulators and self-report questionnaires. Using crowdsourcing, we surveyed 1692 people on auditory, visual, and vibrotactile take-over requests (TORs) in highly automated driving. The survey presented recordings of auditory messages and illustrations of visual and vibrational messages in traffic scenarios of various urgency levels. Multimodal TORs were the most preferred option in high-urgency scenarios. Auditory TORs were the most preferred option in low-urgency scenarios and as a confirmation message that the system is ready to switch from manual to automated mode. For low-urgency scenarios, visual-only TORs were more preferred than vibration-only TORs. Beeps with shorter interpulse intervals were perceived as more urgent, with Stevens’ power law yielding an accurate fit to the data. Spoken messages were more accepted than abstract sounds, and the female voice was more preferred than the male voice. Preferences and perceived urgency ratings were similar in middle- and high-income countries. In summary, this international survey showed that people's preferences for TOR types in highly automated driving depend on the urgency of the situation.

  • 8.
    Björklund, Gunilla
    et al.
    Swedish National Road and Transport Research Institute, Society, environment and transport, Transport economics Stockholm. Dalarna University.
    Åberg, Lars
    Uppsala Universitet.
    Driver behaviour in intersections: Formal and informal traffic rules2005In: Transportation Research Part F: Traffic Psychology and Behaviour, ISSN 1369-8478, E-ISSN 1873-5517, Vol. 8, no 3, p. 239-253Article in journal (Refereed)
    Abstract [en]

    Drivers' behaviour in intersections is not only influenced by the rules of priority in the intersection but also by the design of the intersection as well as the behaviour of other road users. If behaviours that supplement or contradict formal traffic rules become common in a particular traffic intersection, it is an indication that an informal traffic rule has been used. In the present study a sample of 1276 Swedish drivers (aged 18-74 years) responded to questions about how often they would yield to another driver in 10 hypothetical crossing situations. In all crossing situations the respondents were told that there was no major road, implying that they should always yield the right of way to traffic coming from the right (the right-hand ride). The results showed that drivers' reported behaviour varied over different intersections. As expected, the formal rule of priority (i.e., the direction from which the other driver was coming) was an important determinant for drivers' yielding behaviour. However, cues for informal rules such as the other driver's behaviour and road breadth were also of importance. Different groups of drivers could be identified according to their strategies of yielding behaviour. One group of drivers reported that they rarely yielded, whereas another group reported that they always did so. A third group complied with the right-hand rule most of the time, whereas the behaviour of a fourth group varied over intersections. The implications of the results and the appropriateness of the right-hand rule are discussed.

  • 9.
    Blissing, Björn
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Driving Simulation and Visualization.
    Bruzelius, Fredrik
    Swedish National Road and Transport Research Institute, Traffic and road users, Driving Simulation and Visualization.
    Eriksson, Olle
    Swedish National Road and Transport Research Institute, Infrastructure, Infrastructure maintenance.
    Driver behavior in mixed and virtual reality: A comparative study2017In: Transportation Research Part F: Traffic Psychology and Behaviour, ISSN 1369-8478, E-ISSN 1873-5517Article in journal (Refereed)
    Abstract [en]

    This paper presents a comparative study of driving behavior when using different virtual reality modes. Test subjects were exposed to mixed, virtual, and real reality using a head mounted display capable of video see-through, while performing a simple driving task. The driving behavior was quantified in steering and acceleration/deceleration activities, divided into local and global components. There was a distinct effect of wearing a head mounted display, which affected all measured variables. Results show that average speed was the most significant difference between mixed and virtual reality, while the steering behavior was consistent between modes. All subjects but one were able to successfully complete the driving task, suggesting that virtual driving could be a potential complement to driving simulators.

  • 10.
    Booth, Leon
    et al.
    University of New South Wales, Australia; Curtin University, Australia.
    Tan, Tele
    Curtin University, Australia.
    Norman, Richard
    Curtin University, Australia.
    Anund, Anna
    Swedish National Road and Transport Research Institute, Traffic and road users, The Human in the Transport system..
    Pettigrew, Simone
    University of New South Wales, Australia.
    Experiences of older adults interacting with a shared autonomous vehicle and recommendations for future implementation2022In: Transportation Research Part F: Traffic Psychology and Behaviour, ISSN 1369-8478, E-ISSN 1873-5517, Vol. 90, p. 100-108Article in journal (Refereed)
    Abstract [en]

    Introduction: A recognised potential benefit of autonomous vehicles is increased mobility for older adults. However, this group is more apprehensive about adoption, which may hinder uptake. Shared autonomous vehicles (SAVs) represent a use case that may be especially relevant for older people due to emerging applications in retirement villages and similar precincts. However, little research has examined the SAV-related concerns of older adults and strategies to address them. This study used an exploratory approach involving SAV exposure to identify strategies that may increase older people's receptiveness to SAVs. Method: Older adults living in retirement villages (n = 63) were interviewed while interacting with an SAV to examine their needs, expectations, and concerns regarding SAVs. The interview data were coded and thematically analysed. Results: Participants recommended the following approaches to ensuring SAVs are useful and acceptable to older adults: providing physical accessibility for those with mobility impairments, comfortable and practical internal layouts, and operating SAVs on convenient routes at useful speeds. Strategies such as exposing older adults to SAVs in operation to encourage uptake and initially ensuring a human assistant is present were suggested methods of increasing receptivity. Discussion: The findings suggest older passengers are likely to share many of the same reactions to SAVs as the broader population, but with a stronger focus on issues relating to accessibility and the physical layout of the vehicles. The solutions to these issues suggested by the study participants may be useful for those designing SAVs for use in older people's settings and beyond.

  • 11.
    Cacciabue, Pietro Carlo
    et al.
    KITE Solutions.
    Enjalbert, Simon
    Univ. Lille Nord de France.
    Söderberg, Håkan
    Chalmers University of Technology.
    Tapani, Andreas
    Swedish National Road and Transport Research Institute, Society, environment and transport, Traffic analysis and logistics. Linköpings universitet, Kommunikations- och transportsystem.
    Unified Driver Model simulation and its application to the automotive, rail and maritime domains2013In: Transportation Research Part F: Traffic Psychology and Behaviour, ISSN 1369-8478, E-ISSN 1873-5517, Vol. 21, p. 315-327Article in journal (Refereed)
    Abstract [en]

    This paper describes the implementation of a model of a driver into a computerised numerical simulation. The model is developed to capture the essential characteristics and common aspects of cognition and behaviour of a human being in control of a “vehicle” in different surface transport systems, namely trains, cars and ships. The main functions of the simulation are discussed as well as the experiments carried out in different types of driving simulators to support the estimation of the parameters utilised in the numerical simulation. The validation processes carried out in the rail and maritime domains are also discussed together with a critical review of capacities and limitations of the proposed approach.

  • 12.
    Coogan, Matthew A
    et al.
    New England Transportation Institute.
    Campbell, Margaret
    Resource Systems Group, Inc.
    Adler, Thomas J.
    Resource Systems Group, Inc.
    Forward, Sonja
    Swedish National Road and Transport Research Institute, Society, environment and transport, Mobility, actors and planning processes.
    Examining behavioral and attitudinal differences among groups in their traffic safety culture2014In: Transportation Research Part F: Traffic Psychology and Behaviour, ISSN 1369-8478, E-ISSN 1873-5517, Vol. 26, no PB, p. 303-316Article in journal (Refereed)
    Abstract [en]

    The paper explores the concept that, for a given population, there is not a single "traffic safety culture," but rather a set of alternative cultures in which the individual driver might belong. There are several different cultures of dangerous driving behavior and each might need a separate strategy for intervention or amelioration.

    First, the paper summarizes the over-arching theory explored in the research, which applies Multi-group Structural Equation Modeling (MSEM) in a modification of the Theory of Planned Behavior (TPB) in the explanation of Risky Driving Behavior, based on ten observed explanatory factors.

    Second, we apply Latent Class Cluster (LCC) segmentation to the full sample, revealing four segments: one cluster reflecting a "Low Risk Driving Safety Group" and three clusters describing three different groups of problematic drivers. We first apply MSEM to two groups; the "Low Risk Driving Safety Group," and the "High Risk Driving Safety Group," defined as the members of the three problematic clusters together, revealing how a "Low Risk" culture differs from the "High Risk" culture, with the relative importance of the TPB explanatory factors varying sharply between the two groups.

    Finally, the three problematic clusters are profiled for demographics and their mean scores for the ten observed explanatory factors. Each of the clusters is reviewed in terms of responses to selected survey questions.

    Three separate and distinct dangerous traffic safety cultures emerge: first, a culture of risky driving dominated by excitement seeking and optimism bias; a second dominated by denial of societal values; and a third characterized by its propensity to find rational justifications for its speeding behavior.

    The paper applies two research methods together: LCC segmentation divides our sample into meaningful subgroups, while MSEM reveals both within-group analysis of variance and between-group differences in safety attitudes and outcomes. The paper concludes that the combination of the segmentation powers of the LCC and the analysis powers of the MSEM provides the analyst with an improved understanding of the attitudes and behaviors of the separate groups, all tied back to the over-arching theory underlying the research.

  • 13.
    Eriksson, Lars
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Human-vehicle-transport system interaction. Karlstad Universitet.
    Palmqvist, Lisa
    Karlstad Universitet.
    Andersson Hultgren, Jonas
    Swedish National Road and Transport Research Institute, Traffic and road users, Vehicle technology and simulation.
    Blissing, Björn
    Swedish National Road and Transport Research Institute, Traffic and road users, Vehicle technology and simulation.
    Nordin, Steven
    Umeå Universitet.
    Performance and presence with head-movement produced motion parallax in simulated driving2015In: Transportation Research Part F: Traffic Psychology and Behaviour, ISSN 1369-8478, E-ISSN 1873-5517, Vol. 34, p. 54-64, article id 839Article in journal (Refereed)
    Abstract [en]

    Driving simulator studies can reveal relevant and valid aspects of driving behavior, but underestimation of distance and speed can negatively affect the driver's performance, such as in performance of overtaking. One possible explanation for the underestimation of distance and speed is that two-dimensional projection of the visual scene disrupts the monocular-based illusory depth because of conflicting binocular and monocular information of depth. A possible solution might involve the strengthening of the monocular information so that the binocular information becomes less potent.

    In the present study, we used an advanced high-fidelity driving simulator to investigate whether adding the visual depth information of motion parallax from head movement affects sense of presence, judgment of distance and speed, and performance measures coupled with overtaking. The simulations included two types of driving scenario in which one was urban and the other was rural. The main results show no effect of this head-movement produced motion parallax on sense of presence, head movement, time to collision, distance judgment, or speed judgment.

    However, the results show an effect on lateral positioning. When initiating the overtaking maneuver there is a lateral positioning farther away from the road center as effect of the motion parallax in both types of scenario, which can be interpreted as indicating use of naturally occurring information that change behavior at overtaking. Nevertheless, only showing tendencies of effects, absent is any clear additional impact of this motion parallax in the simulated driving.

  • 14.
    Kharrazi, Sogol
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Driver and vehicle.
    Augusto, Bruno
    Swedish National Road and Transport Research Institute, Traffic and road users, Driving Simulation and Visualization.
    Fröjd, Niklas
    Volvo Group Technology.
    Assessing dynamics of heavy vehicles in a driving simulator2019In: Transportation Research Part F: Traffic Psychology and Behaviour, ISSN 1369-8478, E-ISSN 1873-5517, Vol. 65, p. 306-315Article in journal (Refereed)
    Abstract [en]

    This article investigates the potential of a motion based driving simulator in assessing and comparing dynamic performance of different heavy vehicles. A driving simulator study with 55 professional truck drivers is performed and the achieved results show a strong correlation between the objective and subjective measures of the different vehicles performance. The motion based driving simulator is used to compare the performance and controllability of high capacity transport vehicles with conventional heavy vehicles.

  • 15.
    Kircher, Katja
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, The Human in the Transport system..
    Ahlström, Christer
    Swedish National Road and Transport Research Institute, Traffic and road users, The Human in the Transport system.. Linköping University, Sweden.
    A comparison of glance coding approaches for driver attention assessment2024In: Transportation Research Part F: Traffic Psychology and Behaviour, ISSN 1369-8478, E-ISSN 1873-5517, Vol. 100, p. 243-253Article in journal (Refereed)
    Abstract [en]

    Eye tracking is a common tool to assess drivers’ attentional state, either in real-time with the goal to prevent incidents, or offline, to understand underlying processes. While seemingly objective, eye tracking data can be coded and interpreted in different ways, which can have substantial effects on the results. The objective of this paper is to highlight and discuss the possibilities and limitations of three different approaches to code glance data: the direction-based encoding, the target-based approach, and the purpose-based approach. The direction-based coding scheme describes glances relative to the direction of travel. The target-based approach classifies the glance targets into different categories. The purpose-based approach needs additional layers of information to deduce the reason for the glance. This information encompasses road layout, traffic rules, and the presence and relevance of other traffic.

    Data from a field study with 23 participants driving an instrumented vehicle on an urban route was used to illustrate differences between the three methods. The results showed that the coding approach clearly affected the interpretation of the measured glance data. A purely target-based approach is limited by its inability to account for spare visual capacity and that also the absence of a target constitutes valuable information, and a purely direction-based approach does not account for the need to scan areas located off forward. The purpose-based approach requires contextual information that can be cumbersome to integrate. Regardless of the approach used, additional layers of contextual information increase understanding and interpretability, potentially at the cost of increased complexity. The three approaches are suitable for different contexts and their feasibility also depends on the availability of additional data. A key message is that context awareness improves the accuracy of driver attention monitoring and inattention identification.

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  • 16.
    Kircher, Katja
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, The Human in the Transport system..
    Ahlström, Christer
    Swedish National Road and Transport Research Institute, Traffic and road users, The Human in the Transport system.. Linköping University.
    Attentional requirements on cyclists and drivers in urban intersections2020In: Transportation Research Part F: Traffic Psychology and Behaviour, ISSN 1369-8478, E-ISSN 1873-5517, Vol. 68, p. 105-117Article in journal (Refereed)
    Abstract [en]

    Even though often travelling on the same roads, it has been shown that cyclists and car drivers interpret their environment differently, which can lead to misunderstandings and collisions. Based on the Minimum Required Attention (MiRA) theory and the Salience, Effort, Expectancy, Value (SEEV) model, it is investigated whether the attentional requirements put on drivers and cyclists are different in urban intersections, and how difficult it is to fulfil the requirements for the two road user groups. Additionally, glance data from 23 participants who both cycled and drove along an urban route are compared with respect to information sampling strategies and the fulfilment of attentional requirements depending on its type for three intersections. Generally, more attentional requirements existed for cyclists, and due to where they occur relative to the infrastructure, in combination with the physical aspects of cycling, they are less likely to be fulfilled. This was also corroborated by the empirical data, which showed that requirements clearly visible from the infrastructural design are fulfilled more often than those that are not. Overall, the theoretical evaluation of the infrastructure was confirmed by the empirical data, such that the proposed method can be used as a starting point for a theoretical, human centred evaluation of traffic infrastructure.

  • 17.
    Kircher, Katja
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Human Factors in the Transport System.
    Ahlström, Christer
    Swedish National Road and Transport Research Institute, Traffic and road users, Human Factors in the Transport System.
    Nylin, Magnus
    Linköpings Universitet.
    Mengist, Alachew
    Linköpings Universitet.
    Tactical steering behaviour under irrevocable visual occlusion2018In: Transportation Research Part F: Traffic Psychology and Behaviour, ISSN 1369-8478, E-ISSN 1873-5517, Vol. 55, p. 67-77Article in journal (Refereed)
    Abstract [en]

    Objective: To investigate the extent of a driver's mental model with irrevocable visual occlusion and analysing the distance to crash.

    Background: Drivers have a mental model of the immediate surroundings which allows them to predict their own as well as others' travel paths. To navigate safely through traffic, this mental model has to be updated frequently to remain valid. In between information sampling events, the mental model will become outdated over time, as the traffic system is dynamic.

    Method: A simulator study with 22 participants was conducted to investigate the information decay in the mental model. This was implemented by extending visual occlusion until the driver collided with another vehicle or ran off the road, thus providing an estimate of how long it takes until the mental model becomes obsolete.

    Results: An analysis of variance with the factors curve direction, curve radius and traffic showed that curve radius did not influence the distance to crash. Without traffic, drivers veered off the road sooner in right curves. Adding traffic eliminated this difference. Traffic ahead led to a shortened distance to crash. Compared to a tangential travel path from the current lateral position at the time of the occlusion, drivers crashed on average 2.6 times later than they would have, had they not had any mental model of the situation.

    Conclusions: The drivers' mental representation of the future situation seems to include information on how to act, to alleviate deviations in yaw angle, including and considering the presence of other road users.

  • 18.
    Kircher, Katja
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Human-vehicle-transport system interaction.
    Ahlström, Christer
    Swedish National Road and Transport Research Institute, Traffic and road users, Human-vehicle-transport system interaction.
    Palmqvist, Lisa
    Swedish National Road and Transport Research Institute, Traffic and road users, Human-vehicle-transport system interaction.
    Adell, Emeli
    Trivector Traffic.
    Bicyclists‘ speed adaptation strategies when conducting self-paced vs. system-paced smartphone tasks in traffic2015In: Transportation Research Part F: Traffic Psychology and Behaviour, ISSN 1369-8478, E-ISSN 1873-5517, Vol. 28, p. 55-64Article in journal (Refereed)
    Abstract [en]

    The increasing prevalence of mobile phone usage while cycling has raised concerns, even though the number of cyclists involved in accidents does not increase at a comparable rate. A reason for this may be how cyclists adapt travelling speed and task execution to the current traffic situation. The aim of this study is to investigate speed adaptation among cyclists when conducting self-paced (initiated by the cyclist) vs. system-paced (initiated by somebody else) smartphone tasks in real traffic. Twenty-two cyclists completed a track in real traffic while listening to music, receiving and making calls, receiving and sending text messages, and searching for information on the internet. The route and the types of tasks were controlled, but the cyclists could choose rather freely when and where along the route to carry out the tasks, thus providing semi-naturalistic data on compensatory behaviour. The results clearly show that cyclists use conscious strategies to adapt their speed to accommodate the execution of secondary phone tasks. Regarding tactical behaviour, it was found that cyclists kept on cycling in 80% of the system-paced cases and in 70% of the self-paced cases. In the remaining cases, the cyclists chose to execute the phone task while standing still or when walking. Compared to the baseline (17.6 ± 3.5 km/h), the mean speed was slightly increased when the cyclists listened to music (18.2 ± 3.7 km/h) and clearly decreased when they interacted with the phone (13.0 ± 5.0 km/h). The speed reduction profile differed between self-paced and system-paced tasks with a preparatory speed reduction before task initiation for self-paced tasks. In conclusion, when the cyclists had the chance they either stopped or adapted their speed proactively to accommodate the execution of the phone task. For self-paced tasks, the speed reduction was finalised before task initialisation, and for system-paced tasks the speed adaptation occurred in reaction to the incoming task. It is recommended to investigate whether the observed compensatory behaviour is enough to offset the possible negative effects of smartphone use.

  • 19.
    Kircher, Katja
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Trafikanttillstånd, TIL.
    Eriksson, Olle
    Swedish National Road and Transport Research Institute, Infrastructure, Infrastructure maintenance.
    Forsman, Åsa
    Swedish National Road and Transport Research Institute, Traffic and road users, Traffic safety, society and road-user.
    Vadeby, Anna
    Swedish National Road and Transport Research Institute, Traffic and road users, Traffic safety, society and road-user.
    Ahlström, Christer
    Swedish National Road and Transport Research Institute, Traffic and road users, Trafikanttillstånd, TIL.
    Design and analysis of semi-controlled studies2016In: Transportation Research Part F: Traffic Psychology and Behaviour, ISSN 1369-8478, E-ISSN 1873-5517Article in journal (Refereed)
    Abstract [en]

    Semi-controlled studies provide a hybrid approach in between controlled experiments and naturalistic driving studies. As in controlled experiments, the researcher can assign participants to groups, select the route and define the tasks, but the participants are given more freedom when it comes to if, when, where and how to perform the tasks. Increased flexibility makes it possible to investigate how drivers use tactical behaviour to accommodate task execution. The disadvantage is decreased control and more complicated analyses.

    The main objective of this paper is to discuss how to analyse data obtained in semi-controlled studies.The analysis of data from a semi-controlled study include three types of variables:

    • variables that describe the experimental design
    • variables that describe the tactical choices of the participants
    • operational variables such as speed, lateral position or glance behaviour

    To analyse the three types of variables a two-step procedure is suggested. First, the tactical indicators are analysed with regard to the experimental design. Second, the operational indicators are analysed and the tactical indicators are used to divide participants into sub-populations.

    The semi-controlled design does not need any new statistical procedures to be developed. It is more important that the analysis conditions on the initial properties and not on structures that happen to occur during the experiment, like where the participant chose to do a certain task.We recommend to use the semi-controlled study method when investigating questions involving adaptive and compensatory behaviour on the tactical level. It is especially useful if causal relationships are of interest, if the data collection should be accelerated in comparison to naturalistic studies, and if certain geographical locations definitely should be included.

  • 20.
    Kircher, Katja
    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.
    Ahlström, Christer
    Swedish National Road and Transport Research Institute, Traffic and road users, Human-vehicle-transport system interaction.
    Continuous versus intermittent presentation of visual eco-driving advice2014In: Transportation Research Part F: Traffic Psychology and Behaviour, ISSN 1369-8478, E-ISSN 1873-5517, Vol. 24, p. 27-38Article in journal (Refereed)
    Abstract [en]

    Automatic eco-driving advice has the potential to improve fuel economy and reduce emissions. However, providing eco-driving information to the driver will inevitably draw attention away from the driving task. The objective of this research is to investigate the effects of intermittent versus continuous visual eco-driving information on glance behaviour in an attempt to find the best approach to display eco-driving information from a traffic safety perspective.

    Twenty-eight truck drivers drove on a village road, a rural road and a motorway section in an advanced moving base truck simulator. A number of situations with relevance for eco-driving, such as traffic lights, crests, changes in posted speed limits, and a motorway entrance, were investigated. The level of difficulty of the traffic situations varied. Four conditions were tested: baseline without eco-driving information, intermittent feedback, continuous feedback and self-selected feedback (personalised settings selected by the driver).

    As expected, the drivers looked at the eco-driving system when it was active, and more so when the traffic situation was less demanding. Importantly, drivers waited longer with their first glance at the display when the traffic situation was more complex. In conclusion, intermittent information is recommended over continuous information as it leads to shorter dwell times, and as it is easier for the system designer to control when the periods of increased glance frequency occur, by presenting the information in strategically advantageous locations that are not demanding for the driver.

  • 21.
    Kircher, Katja
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Human Factors in the Transport System.
    Ihlström, Jonas
    Swedish National Road and Transport Research Institute, Traffic and road users, Human Factors in the Transport System.
    Nygårdhs, Sara
    Swedish National Road and Transport Research Institute, Traffic and road users, Human Factors in the Transport System.
    Ahlström, Christer
    Swedish National Road and Transport Research Institute, Traffic and road users, Human Factors in the Transport System.
    Cyclist efficiency and its dependence on infrastructure and usual speed2018In: Transportation Research Part F: Traffic Psychology and Behaviour, ISSN 1369-8478, E-ISSN 1873-5517, Vol. 54, p. 148-158Article in journal (Refereed)
    Abstract [en]

    Bicyclists are a heterogeneous group, with varying abilities, traffic education and experience. While efficiency was identified as an important factor on utility bicycle trips, it might be traded for experienced safety, for example by choosing different pathways in a given situation, or by relinquishing one's right of way. In a semi-controlled study with 41 participants, a grouping was made according to self-reported riding speed in relation to other cyclists. The participants cycled twice along a 3 km inner-city route, passing four intersections with different priority rules. The cyclists were free to choose how to negotiate the intersections. Speed and the traffic surroundings were recorded via gps and cameras on the bike of the participant and of a following experimenter. For each cyclist, the ‘base’ speed on undisturbed segments was determined as reference. Based on this, the efficiency in different types of intersections was computed per cyclist group. It turned out that infrastructural aspects, cyclist group and the presence and behaviour of interacting traffic influenced cyclist efficiency. Faster cyclists were delayed more when the infrastructure required a stop regardless of the traffic situation, like at a red traffic light or a stop sign. The members of the so-called ‘comfort cyclists’ group were delayed the most in a roundabout with mixed traffic, where many chose to get off their bike and walk. In a society working for equality of access to the transport system, it is recommended to develop solutions that consider and accommodate the behaviours of different cyclist groups when planning bicycling infrastructure.

  • 22.
    Kircher, Katja
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, The Human in the Transport system..
    Odéen, Martina
    Swedish National Road and Transport Research Institute, Traffic and road users, The Human in the Transport system..
    The role of group membership in active road user attention across different age groups2023In: Transportation Research Part F: Traffic Psychology and Behaviour, ISSN 1369-8478, E-ISSN 1873-5517, Vol. 97, p. 314-327Article in journal (Refereed)
    Abstract [en]

    This study aimed to explore how travelling in different group constellations (alone, with known or with unknown people) affects children's and adults’ visual behaviour in traffic when cycling or walking. Additionally, mobile phone/earphone usage was considered, too. A follow-along study (n = 43) and an observation study (n = 898) were conducted to observe travellers in a natural setting. In the follow-along study, eye-tracking was used to investigate children's glances behaviour on their way to school and how well they manage to fulfil attentional requirements. The observational study focused on children's and adults' visual behaviour at several intersections. The main result of the study was that group membership appears to have a large influence on individuals' visual sampling strategy. In formal groups reliance on each other was found to be stronger than in informal groups. People with a natural responsibility in the group, such as parents or other adults, take a more active role in visual monitoring. Reliance on others is found to a greater extent among pedestrians than cyclists. Regarding communication devices, the use of earphones did not significantly affect glance behaviour towards relevant areas. In naturalistic situations, group constellation, age and phone/earphone usage are interlinked, which needs to be considered when studying these factors.

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  • 23.
    Larsson, Annika F L
    et al.
    Lunds Universitet.
    Kircher, Katja
    Swedish National Road and Transport Research Institute, Traffic and road users, Human-vehicle-transport system interaction.
    Andersson Hultgren, Jonas
    Swedish National Road and Transport Research Institute, Traffic and road users, Vehicle technology and simulation.
    Learning from experience: Familiarity with ACC and responding to a cut-in situation in automated driving2014In: Transportation Research Part F: Traffic Psychology and Behaviour, ISSN 1369-8478, E-ISSN 1873-5517, Vol. 27, p. 229-237Article in journal (Refereed)
    Abstract [en]

    Response times to risky events have been seen to increase with the use of adaptive cruise control (ACC). It has been unclear whether driver experience with ACC mediates this increase. We compare driving in a cut-in event in a simulator both with and without system support, studying ACC as well as ACC with automatic steering. 31 participants were tested in a repeated-measures design, 10 novices and 21 previously experienced with ACC. There was no difference between responding to ACC with and without automatic steering for either group. As expected, we found an increase in response times when driving with system support for both ACC-experienced drivers and ACC-novices. However, this effect was significantly lower for those previously experienced with ACC. This indicates that there is an element of learning involved not only in knowing about system limitations, but also in responding to potential hazards

  • 24.
    Lidestam, Björn
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Driver and vehicle.
    Eriksson, Lars
    Karlstads Universitet.
    Eriksson, Olle
    Swedish National Road and Transport Research Institute, Infrastructure, Infrastructure maintenance.
    Speed perception affected by field of view: Energy-based versus rhythm-based processing2019In: Transportation Research Part F: Traffic Psychology and Behaviour, ISSN 1369-8478, E-ISSN 1873-5517, Vol. 65, p. 227-241Article in journal (Refereed)
    Abstract [en]

    Two experiments were carried out to test speed perception dependency on field of view (FoV), virtual road markings (VRMs), and presentation orders. The primary purpose was to examine how the extent of the optic flow (foremost peripherally–vertically) informs the driver about egospeed. A second purpose was to examine different task demands and stimulus characteristics supporting rhythm-based versus energy-based processing. A third purpose was to examine speed changes indicative of changes in motion sensitivity. Participants were tested in a car simulator, with FoV resembling low front-door windows, and with VRMs inside the car. Three main results were found. Larger FoV, both horizontally and peripherally–vertically, significantly reduced participants' speed, as did VRMs. Delineator posts and road center lines were used for participants' rhythm-based processing, when the task was to drive at target speeds. Rich motion-flow cues presented initially resulted in lower egospeed in subsequent conditions with relatively less motion-flow cues. The practical implication is that non-iconic, naturalistic and intuitive interfaces can effectively instill spontaneous speed adaptation in drivers.

  • 25.
    Miller, K. A.
    et al.
    Loughborough University.
    Filtness, A. J.
    Loughborough University.
    Anund, Anna
    Swedish National Road and Transport Research Institute, Traffic and road users, The Human in the Transport system..
    Maynard, S. E.
    Loughborough University.
    Pilkington-Cheney, F.
    Loughborough University.
    Contributory factors to sleepiness amongst London bus drivers2020In: Transportation Research Part F: Traffic Psychology and Behaviour, ISSN 1369-8478, E-ISSN 1873-5517, Vol. 73, p. 415-424Article in journal (Refereed)
    Abstract [en]

    Driver sleepiness contributes to a substantial proportion of all road crashes. Despite all that is known about driver sleepiness, bus drivers are often overlooked. What is certain is that bus drivers have the potential to suffer from sleepiness as they are shift workers. The current research used a large online survey to investigate sleepiness amongst London bus drivers. There were two aims; to quantify the prevalence of sleepiness amongst London bus drivers, and to determine the factors which contributed to sleepiness. Overall, 20.8% of respondents indicated that they had to fight sleepiness at least 2–3 times a week, and 36.6% of respondents stated that they had experienced a close call due to sleepiness in the past year. There were several potential causes of sleepiness including work, sleep, and personal factors such as obtaining less than 11 h rest between shifts, working 6 or more days without a rest day, and poor self-reported health. These findings show that sleepiness is common amongst London bus drivers and is caused by a combination of factors. The combination of contributory factors suggests that a multifaceted approach should be taken to reduce bus driver sleepiness. © 2020 Elsevier Ltd

  • 26.
    Morris, Andrew
    et al.
    Loughborough University.
    van Nes, Nicole
    SWOV .
    Dukic Willstrand, Tania
    Swedish National Road and Transport Research Institute.
    Charlton, Samuel G.
    University of Waikato.
    HUMANIST 2018-Emerging issues in human factors of vehicle automation: Introduction to the special issue of TRF2020In: Transportation Research Part F: Traffic Psychology and Behaviour, ISSN 1369-8478, E-ISSN 1873-5517, Vol. 74, p. 507-510Article in journal (Other academic)
  • 27.
    Mårdh, Selina
    Swedish National Road and Transport Research Institute, Traffic and road users, Human-vehicle-transport system interaction.
    Identifying factors for traffic safety support in older drivers2016In: Transportation Research Part F: Traffic Psychology and Behaviour, ISSN 1369-8478, E-ISSN 1873-5517, Vol. 38, p. 118-126Article in journal (Refereed)
    Abstract [en]

    The present study aimed at identifying factors for traffic safety support in older drivers. This was achieved by studying the co-operation between older drivers and their ordinary front seat passenger (co-driver). The knowledge emerging from such study can enhance the understanding of what kind of support an older driver needs and also help facilitate proper design of in-vehicle support systems and intervention training programs for older drivers. A within group field study was carried out, using a mixed-methods evaluation design. Four elderly couples participated in the study. The drivers included in the study requested and received on-going directional support, traffic -and driving strategic help, help with look-out and reminding of current speed limit. It was evident from comparisons between interview data and field data that how the participants themselves described their need of support differed from what support they requested (drivers) and gave (co-drivers) in real driving. Furthermore, data revealed that three out of four drivers were given a score of 2 in the Useful Field Of View test (UFOV). It was evident that there are areas in which older drivers need and request support. The results from the present study could be used in the design process, and in evaluation of, in-vehicle support systems as well as in developing intervention training programs customised for older drivers.

  • 28.
    Nilsson, Peter
    et al.
    Chalmers Tekniska Högskola.
    Laine, Leo
    Chalmers Tekniska Högskola.
    Sandin, Jesper
    Swedish National Road and Transport Research Institute, Traffic and road users, Driver and vehicle.
    Jacobson, Bengt
    Chalmers Tekniska Högskola.
    Eriksson, Olle
    Swedish National Road and Transport Research Institute, Infrastructure, Infrastructure maintenance.
    On actions of long combination vehicle drivers prior to lane changes in dense highway traffic: A driving simulator study2018In: Transportation Research Part F: Traffic Psychology and Behaviour, ISSN 1369-8478, E-ISSN 1873-5517, Vol. 55, p. 25-37Article in journal (Refereed)
    Abstract [en]

    In this paper we address drivers’ actions prior to mandatory lane changes of long combination vehicles in dense highway traffic. The studied driver actions were: turn indicator activation, speed reduction and lateral intrusion. We categorised and compared the drivers’ actions with respect to the surrounding traffic cooperation and the level of urgency. Urgency here was based on the remaining distance to a targeted exit ramp. The results show that when the subject vehicle is close to the exit ramp, drivers used speed reduction significantly more than when the vehicle is further away. No significant difference was found for the use of lateral intrusion considering the distance to the exit ramp. As regards traffic cooperation, significant differences were found for both speed reduction and lateral intrusion. The drivers’ speed reduction and lateral intrusion were significantly greater when the surrounding traffic cooperation was low.

  • 29.
    Olsson, Niklas
    Swedish National Road and Transport Research Institute, Traffic and road users, Driver and vehicle. Luleå University of Technology (LTU).
    A validation study comparing performance in a low-fidelity train-driving simulator with actual train driving performance2023In: Transportation Research Part F: Traffic Psychology and Behaviour, ISSN 1369-8478, E-ISSN 1873-5517, Vol. 97, p. 109-122Article in journal (Refereed)
    Abstract [en]

    Background: Although common in other industries, such as the automotive sector, no train-driving validation study has been found in the existing literature. The present paper intends to fill that gap by comparing the results of train-driving performance in a physically low-fidelity but highly functional simulator with real train-driving performance.

    Method: Thirty-four train driver students in the final part of their basic education were assessed in a 45-minute simulator test using the number of driving errors as the performance indicator. The results were compared with the performance at 11 weeks of internship as measured by supervisors grading according to a standard procedure. One of the classes (17 to-be drivers) was affected by restrictions related to COVID-19, which led to a shortened internship and distance learning during parts of the internship. The study also intended to measure the effect of the restrictions and the types of errors the drivers made by comparing the two classes.

    Results: A significant correlation was found between the number of driving errors and internship grades, r = −0.45, p <.05. The results also revealed that COVID-19 restrictions negatively affected performance, as the students from Class B made significantly more driving errors and obtained a lower internship grade than those from Class A.

    Conclusions: This paper shows that this type of low-fidelity simulator is well suited for measuring real train-driving performance. A measurement method that can predict long-term driving should have implications for both research and practical usability. Researchers can use this for studying the effects of, for example, different training methods, while train operation companies can use the method to test their drivers' skills and intervene before an actual accident occurs.

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  • 30.
    Stephens, A. N.
    et al.
    Monash University, Australia.
    Stephan, K. L.
    Monash University, Australia.
    Crotty, R.
    Monash University, Australia.
    O'Hern, S.
    Monash University, Australia; Tampere University, Finland.
    Björklund, Gunilla
    Swedish National Road and Transport Research Institute, Society, environment and transport, Mobility, actors and planning processes.
    Too close for comfort: A mixed methods study to understand self-reported tailgating using the theory of planned behaviour2023In: Transportation Research Part F: Traffic Psychology and Behaviour, ISSN 1369-8478, E-ISSN 1873-5517, Vol. 93, p. 11-22Article in journal (Refereed)
    Abstract [en]

    Background: Tailgating (following a lead vehicle too closely) is a key contributor to crashes and injury. While vehicle technology has the potential to reduce the trauma resulting from tailgating, full market penetration of these technologies is some time away. In the meantime, efforts to improve road safety can focus on supporting safer driver behaviour by targeting motivations for this behaviour.

    Method: A mixed methods design was used to understand reasons why drivers tailgate and potential countermeasures to reduce this behaviour. Qualitative data from 247 drivers (males = 29 %; mean age = 39.86; SD = 14.39) were sought to understand circumstances when drivers are tailgated and when they report tailgating. In a second study, 736 drivers (males = 41 %; mean age = 37.69; SD = 14.27) responded to questions developed from the qualitative findings to quantify the frequency of tailgating and reasons behind it. The theory of planned behaviour (TPB) was applied to understand whether self-reported intention to tailgate could be predicted by attitudes, perceived social acceptance of the behaviour, perceived behavioural control, and past tailgating behaviour.

    Results: Tailgating was a common behaviour. All drivers in the first study had experienced being tailgated by other drivers, while 77% had tailgated other vehicles; albeit 55% reported this was rare. Tailgating was unintentional (due to dense traffic; or lack of knowledge of safe following distance recommendations) or intentional (due to pressure from other drivers, anger or to change others’ behaviour). Structural equation modelling showed that TPB constructs of attitude, social norms, perceived behavioural control and past tailgating behaviour predicted intention to tailgate, accounting for 66% of the variance.

    Conclusion: TPB is a useful framework for explaining tailgating behaviour, or at least the intention to tailgate, and to develop interventions. These could focus on education of the risks of tailgating, the recommended safe following distances as well as strategies to support drivers maintaining safe following distances across different speed zones

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  • 31.
    Strand, Niklas
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Human-vehicle-transport system interaction.
    Nilsson, Josef
    SP Technical Research Institute of Sweden.
    Karlsson, I.C. MariAnne
    Chalmers Tekniska Högskola.
    Lena, Nilsson
    Swedish National Road and Transport Research Institute, Traffic and road users.
    Semi-automated versus highly automated driving in critical situations caused by automation failures2014In: Transportation Research Part F: Traffic Psychology and Behaviour, ISSN 1369-8478, E-ISSN 1873-5517Article in journal (Refereed)
    Abstract [en]

    The purpose of this study was to examine the effects of vehicle automation and automation failures on driving performance. Previous studies have revealed problems with driving performance in situations with automation failures and attributed this to drivers being out-of-the-loop. It was therefore hypothesized that driving performance is safer with lower than with higher levels of automation. Furthermore, it was hypothesized that driving performance would be affected by the extent of the automation failure. A moving base driving simulator was used. The design contained semi-automated and highly automated driving combined with complete, severe, and moderate deceleration failures. In total the study involved 36 participants. The results indicate that driving performance degrades when the level of automation increases. Furthermore, it is indicated that car drivers are worse at handling complete than partial deceleration failures.

  • 32.
    Svenson, Ola
    et al.
    Stockholms universitet.
    Eriksson, Gabriella
    Swedish National Road and Transport Research Institute, Traffic and road users, Human-vehicle-transport system interaction. Stockholms universitet.
    Salo, Ilkka
    Lunds universitet.
    Peters, Ellen
    Ohio State University.
    Judgments of mean speed and predictions of route choice2011In: Transportation Research Part F: Traffic Psychology and Behaviour, ISSN 1369-8478, E-ISSN 1873-5517, Vol. 14, no 6, p. 504-511Article in journal (Refereed)
    Abstract [en]

    How are driving speeds integrated when speeds vary along a route? In a first study, we examined heuristic processes used in judgments of mean speed when the mean speeds on parts of the trip varied. The judgments deviated systematically from objective mean speeds because the distances driven at different speeds were given more weight than travel time spent on the different distances.

    The second study showed that when there was a 10-15 min pause during a travel the effect on the mean speed decrease was underestimated for driving speeds of 90 km/h and higher. In the third study, the objective mean speeds and the subjective biased mean speed judgments were used to predict choices between routes with different speed limits. The results showed that subjective judgments predicted decisions to maximize mean speed significantly better than objective mean speeds. Finally, some applied and basic research implications of the results were discussed.

  • 33.
    Thorslund, Birgitta
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Driver and vehicle.
    Lindström, Anders
    Swedish National Road and Transport Research Institute.
    Cyclist strategies and behaviour at intersections. Conscious and un-conscious strategies regarding positioning2020In: Transportation Research Part F: Traffic Psychology and Behaviour, ISSN 1369-8478, E-ISSN 1873-5517, Vol. 70, p. 149-162Article in journal (Refereed)
    Abstract [en]

    Severe and even fatal accidents between cyclists and motor vehicles commonly occur at intersections. Many of these accidents occur with right-turning vehicles, with drivers not observing an adjacent cyclist. Few structured investigations exist regarding the interaction between cyclist and motor vehicle, and factors in need of study are how infrastructure and vehicle properties affect human decision-making and cycling behaviour. Therefore, a bicycle simulator study was performed, where vehicle type, presence of lane markings and lane width were systematically varied in a scenario with a cyclist approaching a vehicle from behind, at a signalized city intersection. 33 participants cycled through 8 intersection variants each. Data on cycling trajectories, stopping points and speed was coupled with survey data from the participants, and semantically categorized verbal responses to questions regarding strategy for choice of stopping point. Results show that all three factors (vehicle type, lane markings and available vehicle-adjacent space) significantly affects cyclists’ behaviour and conscious strategies. Participants were more cautious in the presence of a truck than a car, reflected in choice of position when cycling and stopping, and in explicit verbalisations regarding perilous aspects of the situation and their conscious and strategic choice of positioning. Available lateral space also affected stop positions and feeling of safety (expressed verbally). Presence of bicycle lane markings made the cyclists inclined to continue into the space to the right of the vehicle. This was revealed by their positioning and speed, and also apparent in the verbal expressions, especially the positive remarks on the situation and conditions. However, the perceived comfort with lane markings present was actually lower than when they were missing. Cyclist type (slow, moderate, or fast) matters with the self-reported faster cyclists being more prone to stop to the right than the slower one.

  • 34.
    Thorslund, Birgitta
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Driver and vehicle.
    Nygårdhs, Sara
    Swedish National Road and Transport Research Institute, Traffic and road users, Human Factors in the Transport System.
    Malicka, A. N.
    La Trobe University.
    Black, A. A.
    Queensland University of Technology.
    Hickson, L.
    The University of Queensland.
    Wood, J. M.
    Queensland University of Technology.
    Exploring older adults hearing and vision and driving: The Swedish study2019In: Transportation Research Part F: Traffic Psychology and Behaviour, ISSN 1369-8478, E-ISSN 1873-5517, Vol. 64, p. 274-284Article in journal (Refereed)
    Abstract [en]

    Aim: The aims of this study were to evaluate the self-reported driving abilities and use of visual and hearing aids for driving, among older adults with varying degrees of hearing impairment (HI), vision impairment (VI) and dual sensory impairment (DSI). Visual processing related to driving performance was also assessed to provide a laboratory-based index of driving ability and safety. The research examined the associations between self-reported and clinically measured vision and hearing, and how they related to the level of comfort in various driving situations and the use of hearing and vision aids (spectacles) when driving.

    Method: Participants included 109 older adults (58 women, 51 men) aged over 60 years (M age = 69.5 years (SD = 5.25), age range: 60–87) who held a valid driver's license. Following attendance at the testing session that involved clinical measures of vision and hearing and an assessment of visual processing abilities, the participants were categorized into four groups according to their hearing and vision abilities: no visual or hearing impairment (NI), corrected visual impairment (CVI), hearing impairment (HI), and corrected visual impairment combined with hearing impairment (CVHI). All participants filled in a questionnaire covering subjective measures of vision, hearing, driving habits, and use of vision and hearing aids.

    Results and Conclusion: There was a strong association between most of the subjective and objective measures of both hearing and vision, which indicates that participants in this study were aware of their abilities to some extent. Better hearing and vision measures were associated with higher level of comfort in several traffic situations. The results also show that spectacles are used more than hearing aids when driving (95% versus 57% of the time respectively). In addition, both the measured and the experienced benefits of hearing aids were significantly associated with the amount of hearing aid use when driving. The findings of this study provide the basis for larger scale studies to explore the impact of hearing and visual impairment on driving and the use of vision and hearing aids and should also include participants who have visual impairment even with their optimal optical correction to fully explore these effects.

  • 35.
    Thorslund, Birgitta
    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.
    Lidestam, Björn
    Linköping University.
    Lyxell, Björn
    Linköping University.
    Cognitive workload and driving behavior in persons with hearing loss2013In: Transportation Research Part F: Traffic Psychology and Behaviour, ISSN 1369-8478, E-ISSN 1873-5517, Vol. 21, p. 113-121Article in journal (Refereed)
    Abstract [en]

    Purpose: To compare the effect of cognitive workload in individuals with and without hearing loss, respectively, in driving situations with varying degree of complexity.

    Methods: 24 participants with moderate hearing loss (HL) and 24 with normal hearing (NH) experienced three different driving conditions: Baseline driving; Critical events with a need to act fast; and a Parked car event with the possibility to adapt the workload to the situation. Additionally, a Secondary task (observation and recalling of 4 visually displayed letters) was present during the drive, with two levels of difficulty in terms of load on the phonological loop. A tactile signal, presented by means of a vibration in the seat, was used to announce the Secondary task and thereby simultaneously evaluated in terms of effectiveness when calling for driver attention. Objective driver behavior measures (M and SD of driving speed, M and SD of lateral position, time to line crossing) were accompanied by subjective ratings during and after the test drive.

    Results: HL had no effect on driving behavior at Baseline driving, where no events occurred. Both during Secondary task and at the Parked car event HL was associated with decreased mean driving speed compared to baseline driving. The effect of HL on the Secondary task performance, both at Baseline driving and at the lower Difficulty Level at Critical events, was more skipped letters and fewer correctly recalled letters. At Critical events, task difficulty affected participants with HL more. Participants were generally positive to use vibrations in the seat as a means for announcing the Secondary task.

    Conclusions: Differences in terms of driving behavior and task performance related to HL appear when the driving complexity exceeds Baseline driving either in the driving task, Secondary task or a combination of both. This leads to a more cautious driving behavior with a decreased mean driving speed and less focus on the Secondary task, which could be a way of compensating for the increasing driving complexity. Seat vibration was found to be a feasible way to alert drivers with or without HL.

  • 36.
    Vogel, Katja
    Swedish National Road and Transport Research Institute.
    What characterizes a free vehicle in an urban area?2002In: Transportation Research Part F: Traffic Psychology and Behaviour, ISSN 1369-8478, E-ISSN 1873-5517, Vol. 5, no 1, p. 313-327Article in journal (Refereed)
    Abstract [en]

    The concept "free vehicle" is used widely in the transportation research literature, but as yet there is no common standard for a definition. In this article a standard is provided that is based on the assumption that a vehicle can be considered free, when its speed is not influenced by the speed of the vehicle traveling ahead. In order to determine empirically a threshold for free vehicles in urban areas, speed, distance headway, and time headway data of more than 100 000 vehicles were analyzed. Analyses showed that the speeds of two vehicles are linearly dependent on time headway for headways up to 6 s. It is important to distinguish between this value and the drivers' preferred headway, which is in the region of 2 s

  • 37.
    Wallen Warner, Henriette
    et al.
    Swedish National Road and Transport Research Institute, Society, environment and transport, Mobility, actors and planning processes.
    Åberg, Lars
    Uppsala Universitet.
    Drivers' tendency to commit different aberrant driving behaviours in comparison with their perception of how often other drivers commit the same behaviours2014In: Transportation Research Part F: Traffic Psychology and Behaviour, ISSN 1369-8478, E-ISSN 1873-5517, Vol. 27, no PA, p. 37-43Article in journal (Refereed)
    Abstract [en]

    The aim of the present study is to examine the difference between drivers' self-reported tendency to commit different aberrant driving behaviours in comparison with their perception of how often other drivers commit the same behaviours measured by the driver behaviour questionnaire (DBQ) in Sweden and Turkey, respectively. A sample of 228 Swedish and 302 Turkish drivers completed a questionnaire including questions based on the DBQ. The results showed that in both Sweden and Turkey, the participants reported committing aberrant driving behaviours less frequently than their perception of how often other drivers commit the same behaviours. The size of this difference does, however, vary depending on the DBQ-item and it is suggested that this variation could be used as a clue for understanding social acceptability.

  • 38.
    Wallén Warner, Henriette
    Swedish National Road and Transport Research Institute, Society, environment and transport, Mobility, actors and planning processes.
    Beliefs about riding a bicycle when mildly alcohol intoxicated2021In: Transportation Research Part F: Traffic Psychology and Behaviour, ISSN 1369-8478, E-ISSN 1873-5517, Vol. 76, p. 384-392Article in journal (Refereed)
    Abstract [en]

    Alcohol intoxication appears to be a contributing factor to many bicycle crashes with serious consequences. Despite this, there is no specific limit on the blood alcohol concentration permissible when cycling in Sweden, and there is very little knowledge of the perception of sobriety associated with cycling. The aim of this study is therefore to identify the behavioural, normative, and control beliefs underpinning cyclists’ attitude, subjective norm, and perceived behavioural control associated with riding a bicycle when mildly alcohol intoxicated. A total of 34 participants answered questions based on the theory of planned behaviour (Ajzen, 1991). The results indicate that the participants saw great advantages (practical, free, safe, nice, and better than taking the car), but also disadvantages (impaired ability, danger to oneself, and danger to others) from cycling when mildly alcohol intoxicated. Furthermore, they identified both factors making it easier (small amounts of alcohol, bicycle-friendly infrastructure/conditions, poor alternatives, group pressure, and emergency situations) and more difficult (large amounts of alcohol, aggravating circumstances, bicycle-unfriendly infrastructure/conditions, good alternatives, social censure, group resistance, parenthood, and experience) to opt to cycle when mildly alcohol intoxicated. Finally, some participants believed that certain people (e.g. students, people with poor finances, and nearly everyone) think that it is acceptable to cycle when mildly alcohol intoxicated, while others (e.g. parents, responsible people, and nearly no group) think that it is unacceptable. These results support the use of information dissemination/campaigns to reduce the incidence of cycling when alcohol intoxicated and/or the amount of alcohol consumed in connection with cycling. At the same time, they do not support the introduction of a specific limit on the blood alcohol concentration permissible when cycling, and the potential of improved public transport to reduce the number of inebriated cyclists is uncertain.

  • 39.
    Wallén Warner, Henriette
    Swedish National Road and Transport Research Institute, Society, environment and transport, Mobility, actors and planning processes.
    Using direct and belief-based measures of the theory of planned behaviour to predict intention to cycle when mildly intoxicated2023In: Transportation Research Part F: Traffic Psychology and Behaviour, ISSN 1369-8478, E-ISSN 1873-5517, Vol. 93, p. 133-142Article in journal (Refereed)
    Abstract [en]

    Alcohol intoxication seems to be an important contributing factor to cyclist injury and death in traffic. The first aim of this study was to examine how much of the variance in intention to cycle when mildly alcohol intoxicated during the coming year could be explained by only three direct measures of attitude, subjective norm, and perceived behavioural control, and by indices constructed from the belief-based measures, respectively. The second aim was to identify the belief composites that contributed to the prediction direct measures of attitude, subjective norm, perceived behavioural control, and intention, regarding cycling when mildly alcohol intoxicated during the coming year. A sample of cyclists (n = 196) completed a postal questionnaire including both direct and belief-based measures of the latent variables in the theory of planned behaviour. The results indicated that the three direct measures of attitude, subjective norm, and perceived behavioural control contributed more to the prediction of drivers’ intention to cycle when alcohol intoxicated than did the 33 indices constructed from belief-based measures. This suggests that three items is sufficient to predict peoples intention. Standard multiple regressions then showed which of the belief composites contributed to the prediction of attitude, subjective norm, and perceived behavioural control, as well as intention. These identified beliefs could be used to, for example, develop effective road safety campaigns, but it is important to remember that these beliefs might not be directly transferable to other groups of people and that all campaigns must be based on the beliefs of their specific target audience.

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  • 40.
    Wallén Warner, Henriette
    et al.
    Swedish National Road and Transport Research Institute, Society, environment and transport, Mobility, actors and planning processes.
    Andersson, Jan
    Swedish National Road and Transport Research Institute, Traffic and road users.
    Patten, Christopher
    Swedish Transport Agency, Sweden.
    Shared space: Different age groups’ perspectives2022In: Transportation Research Part F: Traffic Psychology and Behaviour, ISSN 1369-8478, E-ISSN 1873-5517, Vol. 90, p. 167-180Article in journal (Refereed)
    Abstract [en]

    Background: Shared spaces, in the context of road transport, often refer to areas shared by unprotected and protected road users and intended to facilitate a living city space for every-one. A basic idea behind shared spaces is to create traffic safety by inducing some uncertainty. This study investigates how young, middle-aged, and elderly pedestrians experience shared space, as well as whether and, if so, how two shared space designs (without and with large flowerpots) affect this experience.

    Method: Thirty-seven participants, divided into three age groups, participated in the study, conducted in Fisherman's Square, Västervik, Sweden. An adjacent non-signal-regulated pedestrian crossing was used as a control. Two studies – visual scanning and Q studies – were combined. In the visual scanning study, eye-tracking examined how the two designs affected the participants’ visual scanning behaviour (i.e., what participants looked at) as pedestrians. In the Q-study, Q-methodology was used to examine how the two designs affected the participants’ experiences as pedestrians.

    Results: The visual scanning study showed that different age groups were affected in different ways by designs without and with large flowerpots in the shared space. While the middle-aged participants always glanced more often at traffic-relevant objects, and young participants always glanced equally often at traffic-relevant and non-traffic-relevant objects, the elderly participants changed their visual scanning behaviour depending on the design. Without large flowerpots deployed, the elderly participants glanced more often at traffic-relevant than non-traffic-relevant objects. No such difference was obtained when large flowerpots were deployed. The Q-study showed that participants, regardless of age, experienced no great uncertainty in this shared space. The perceived uncertainty, which nevertheless existed, was reduced with large flowerpots deployed to recreate the traditional division with clear zones where pedestrians could stay in relatively car-free areas while motor vehicles had clear paths to travel along.

    Conclusion: The results suggest that shared space, without large flowerpots, succeeded in inducing some uncertainty, especially among middle-aged and elderly pedestrians. However, deploying large flowerpots seemed to decrease this uncertainty, especially among elderly pedestrians. The major concern prompted by these results is how this decreased uncertainty affects traffic safety. Shared space also needs to be studied from the car driver's perspective to understand the interaction between different road user groups. © 2022 The Author(s)

  • 41.
    Wallén Warner, Henriette
    et al.
    Swedish National Road and Transport Research Institute, Society, environment and transport, Mobility, actors and planning processes.
    Björklund, Gunilla
    Swedish National Road and Transport Research Institute, Society, environment and transport, Transport economics. Swedish National Road and Transport Research Institute, Society, environment and transport, Mobility, actors and planning processes.
    Andersson, Jan
    Swedish National Road and Transport Research Institute, Traffic and road users.
    Using a three-stage model of change to understand people's use of bicycle, public transport, and car2021In: Transportation Research Part F: Traffic Psychology and Behaviour, ISSN 1369-8478, E-ISSN 1873-5517, Vol. 82, p. 167-177Article in journal (Refereed)
    Abstract [en]

    More active ways of travelling (e.g., walking, cycling, and public transport) would benefit both individuals and society. To encourage people's transition to more active travelling, it is important to understand the decision-making process regarding modal choice. The first aim of this study is therefore to combine a three-stage version of the transtheoretical model of change (TTM; Prochaska & DiClemente, 1983) with the theory of planned behaviour (TPB; Ajzen, 1991) to advance our understanding of the nature of the TTM stages. The second aim is to examine certain characteristics (i.e., age, gender, importance of everyday exercise, importance of environmental issues, perceived accessibility, and satisfaction with travel) of these three stages of change. The study used a web-based questionnaire, an app-based questionnaire, and an app-based travel diary completed by 306 people in the Stockholm area. The observed behaviour measured using the app-based travel diary showed that the three-stage model used in this study was consistent with the participants’ self-reported travel behaviour in using bicycles, public transport, and cars. Interventions focusing on attitude, subjective norm, and perceived behavioural control appear to have potential to move people from one stage to another regardless of initial stage. To make interventions as effective as possible, the stage of change as well as the behavioural, normative, and control beliefs underpinning attitude, subjective norm, and perceived behavioural control must be considered. Finally, more research is needed to advance our knowledge of the relationship between the three stages of change and other variables. © 2021 The Author(s)

  • 42.
    Warner, Henriette Wallen
    et al.
    Swedish National Road and Transport Research Institute, Society, environment and transport, Mobility, actors and planning processes.
    Forward, Sonja
    Swedish National Road and Transport Research Institute, Society, environment and transport, Mobility, actors and planning processes.
    The effectiveness of road safety interventions using three different messages: Emotional, factual or a combination of both messages2016In: Transportation Research Part F: Traffic Psychology and Behaviour, ISSN 1369-8478, E-ISSN 1873-5517, Vol. 36, p. 25-34Article in journal (Refereed)
    Abstract [en]

    The present study is an evaluation of a road safety intervention programme dealing with alcohol in traffic. The intervention was based on a programme developed by the Swedish Road Administration using three different messages. The aim of the study was to evaluate which message (emotional, factual or a combination of both messages) had the largest effect on the variables included in the theory of planned behaviour (TPB).

    Of the 930 Senior High School Students who took part in the study 265 received an emotional message, 251 received a factual message, 254 received a combination of both messages and 160 were assigned to a control group who did not receive any message. Two scenarios were used describing situations where the participants would receive a lift from someone who had drunk two 'strong' beers and was either someone they did not know very well or their best friend.

    The results showed that the intervention combining the emotional and the factual message had the largest effect on the variables included in the theory of planned behaviour (TPB). Attitude was affected the most by the interventions while further activities need to be taken in order to better target perceived behavioural control and especially subjective norm and thereby also intention.

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