Publications
Change search
Refine search result
12 1 - 50 of 74
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Abtahi, Farhad
    et al.
    Kungliga Tekniska Högskolan.
    Anund, Anna
    Swedish National Road and Transport Research Institute, Traffic and road users, Human Factors in the Transport System.
    Fors, Carina
    Swedish National Road and Transport Research Institute, Traffic and road users, Human Factors in the Transport System.
    Seoane, Fernando
    Kungliga Tekniska Högskolan.
    Lindecrantz, Kaj
    Kungliga Tekniska Högskolan.
    Association of drivers’ sleepiness with heart rate variability: A pilot study with drivers on real roads2018In: IFMBE Proceedings, Springer Verlag , 2018, Vol. 65, p. 149-152Conference paper (Refereed)
    Abstract [en]

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

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

  • 2.
    Ahlström, Christer
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Human Factors in the Transport System.
    Anund, Anna
    Swedish National Road and Transport Research Institute, Traffic and road users, Human Factors in the Transport System.
    Fors, Carina
    Swedish National Road and Transport Research Institute, Traffic and road users, Human Factors in the Transport System.
    Åkerstedt, Torbjörn
    Karolinska Institutet.
    Effects of the road environment on the development of driver sleepiness in young male drivers2018In: Accident Analysis and Prevention, ISSN 0001-4575, E-ISSN 1879-2057, Vol. 112, p. 127-134Article in journal (Refereed)
    Abstract [en]

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

  • 3.
    Ahlström, Christer
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Human Factors in the Transport System.
    Anund, Anna
    Swedish National Road and Transport Research Institute, Traffic and road users, Human Factors in the Transport System.
    Fors, Carina
    Swedish National Road and Transport Research Institute, Traffic and road users, Human Factors in the Transport System.
    Åkerstedt, Torbjörn
    Stockholms Universitet.
    The effect of daylight versus darkness on driver sleepiness: A driving simulator study2017In: Journal of Sleep Research, ISSN 0962-1105, E-ISSN 1365-2869Article in journal (Refereed)
    Abstract [en]

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

  • 4.
    Ahlström, Christer
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Trafikanttillstånd, TIL.
    Ihlström, Jonas
    Swedish National Road and Transport Research Institute, Traffic and road users, Trafikanttillstånd, TIL.
    Kircher, Katja
    Swedish National Road and Transport Research Institute, Traffic and road users, Trafikanttillstånd, TIL.
    Förares användning av kommunikationsutrustning under färd: Del 1: Enkätstudie. Del 2: Användning enligt objektiv mätning2017Report (Other academic)
    Abstract [sv]

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

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

  • 5.
    Ahlström, Christer
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Trafikanttillstånd, TIL.
    Jansson, Sabina
    Linköpings Universitet.
    Anund, Anna
    Swedish National Road and Transport Research Institute, Traffic and road users, Trafikanttillstånd, TIL.
    Local changes in the wake electroencephalogram precedes lane departures2017In: Journal of Sleep Research, ISSN 0962-1105, E-ISSN 1365-2869Article in journal (Refereed)
    Abstract [en]

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

  • 6.
    Ahlström, Christer
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Human Factors in the Transport System.
    Kircher, Katja
    Swedish National Road and Transport Research Institute, Traffic and road users, Human Factors in the Transport System. Linköpings Universitet.
    A Generalized Method to Extract Visual Time-Sharing Sequences From Naturalistic Driving Data2017In: IEEE transactions on intelligent transportation systems (Print), ISSN 1524-9050, E-ISSN 1558-0016, Vol. 18, no 11, p. 2929-2938Article in journal (Refereed)
    Abstract [en]

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

  • 7.
    Ahlström, Christer
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Trafikanttillstånd, TIL.
    Kircher, Katja
    Swedish National Road and Transport Research Institute, Traffic and road users, Trafikanttillstånd, TIL. Linköping University.
    Changes in glance behaviour when using a visual eco-driving system: A field study2017In: Applied Ergonomics, ISSN 0003-6870, E-ISSN 1872-9126, Vol. 58, p. 414-423Article in journal (Refereed)
    Abstract [en]

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

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

  • 8.
    Andersson, Jan
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Human-vehicle-transport system interaction.
    Renner, Linda
    Swedish National Road and Transport Research Institute, Traffic and road users, Human-vehicle-transport system interaction.
    Sandin, Jesper
    Swedish National Road and Transport Research Institute, Traffic and road users, Human-vehicle-transport system interaction. Swedish National Road and Transport Research Institute, Traffic and road users, Driver and vehicle.
    Fors, Carina
    Swedish National Road and Transport Research Institute, Traffic and road users, Vehicle technology and simulation. Swedish National Road and Transport Research Institute, Traffic and road users, Human Factors in the Transport System.
    Strand, Niklas
    Swedish National Road and Transport Research Institute, Traffic and road users, Vehicle technology and simulation. Swedish National Road and Transport Research Institute, Traffic and road users, Driver and vehicle.
    Hjort, Mattias
    Swedish National Road and Transport Research Institute, Traffic and road users, Human-vehicle-transport system interaction. Swedish National Road and Transport Research Institute, Traffic and road users, Driver and vehicle.
    Andersson Hultgren, Jonas
    Swedish National Road and Transport Research Institute.
    Almqvist, Sverker
    Swedish National Road and Transport Research Institute.
    Trafiksäkerhetspåverkan vid omkörning av 30-metersfordon2011Report (Other academic)
    Abstract [en]

    The Swedish Road Administration considers permitting longer and heavier trucks on Swedish roads, provided that they do not affect traffic safety. The purpose of the study was to investigate the effect of truck length, particularly accident risk associated with overtaking. Interviewed drivers of 30 meter trucks had not experienced the problems predicted by drivers of ordinary trucks concerning narrow roundabouts and intersections, but mentioned the importance of a supportive truck company, working environment and truck equipment. A simulator study investigated car drivers overtaking trucks 30 m and 18.75 m long on a 2+1 road where two lanes merges to one. The headway time gap was 0.2 sec. (sign.) shorter after overtaking the 30 meter truck in situations where the back was in the same relative position as of the 18.75 meter truck. A field study analysed video-recorded overtakings of a 30 meter and a 24 meter timber truck on a 2+1 road and a two-lane road. No significant differences were found between headway time gaps when overtaking the two trucks, regardless of road type. The latter result should be interpreted with great caution because of unevenly distributed data collected during specific conditions. The conclusions are that longer trucks may have a small negative effect on overtaking situations, and that further field studies are required.

  • 9.
    Anund, Anna
    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.
    Fors, Carina
    Swedish National Road and Transport Research Institute, Traffic and road users, Human Factors in the Transport System.
    Åkerstedt, Torbjörn
    Karolinska Institutet.
    Are professional drivers less sleepy than non-professional drivers?2018In: Scandinavian Journal of Work, Environment and Health, ISSN 0355-3140, E-ISSN 1795-990X, Vol. 44, no 1, p. 88-95Article in journal (Refereed)
    Abstract [en]

    Objective It is generally believed that professional drivers can manage quite severe fatigue before routine driving performance is affected. In addition, there are results indicating that professional drivers can adapt to prolonged night shifts and may be able to learn to drive without decreased performance under high levels of sleepiness. However, very little research has been conducted to compare professionals and non-professionals when controlling for time driven and time of day.

    Method The aim of this study was to use a driving simulator to investigate whether professional drivers are more resistant to sleep deprivation than non-professional drivers. Differences in the development of sleepiness (self-reported, physiological and behavioral) during driving was investigated in 11 young professional and 15 non-professional drivers.

    Results Professional drivers self-reported significantly lower sleepiness while driving a simulator than nonprofessional drivers. In contradiction, they showed longer blink durations and more line crossings, both of which are indicators of sleepiness. They also drove faster. The reason for the discrepancy in the relation between the different sleepiness indicators for the two groups could be due to more experience to sleepiness among the professional drivers or possibly to the faster speed, which might unconsciously have been used by the professionals to try to counteract sleepiness.

    Conclusion Professional drivers self-reported significantly lower sleepiness while driving a simulator than non-professional drivers. However, they showed longer blink durations and more line crossings, both of which are indicators of sleepiness, and they drove faster.

  • 10.
    Anund, Anna
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Trafikanttillstånd, TIL.
    Blissing, Björn
    Swedish National Road and Transport Research Institute, Traffic and road users, Körsimulering och visualisering, SIM.
    Saluäär, Dennis
    Volvo AB.
    Svanberg, Bo
    Volvo Car Corporation.
    Ljung Aust, Mikael
    Volvo Car Corporation.
    Holmertz, Pontus
    HiQ.
    Night-time scenarios in simulators: a prestudy of needs, knowledge and possible solutions2016Report (Other academic)
    Abstract [en]

    The study in this publication investigates the need and potential for night-time scenarios in driving simulators, determines how such night-time scenarios could be reproduced and identifies the objects most important to reproduce. Although on average 12 out of every 24 hours are dark and considering that most situations are more demanding for drivers in dark conditions, simulations of driving scenarios with different degrees of darkness are not common. The project work comprised a pre-study that involved an investigation of the need and potential of night-time scenarios with the help of input from different stakeholders, consolidation of what is known up to now through benchmarking and state of the art, and a review of available technical solutions. The objective was to identify pros and cons with existing solutions and aspects that are important to consider in order to reproduce the most important components in realistic night-time scenarios. Based on the results, six important use cases were identified and two of these (‘Driver fatigue’ and ‘Objects without light sources’) were studied in more detail. It was concluded that for night-time scenarios there is enough darkness in general in the simulator environment. The question is whether it is possible to create sufficient contrast for objects that are meant to be observable. For daytime scenarios, the light levels in the simulator are clearly unrealistically low and this limitation might even trigger unwanted sleepiness.

  • 11.
    Anund, Anna
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Trafikanttillstånd, TIL. Linköpings Universitet.
    Fors, Carina
    Swedish National Road and Transport Research Institute, Traffic and road users, Trafikanttillstånd, TIL.
    Ahlström, Christer
    Swedish National Road and Transport Research Institute, Traffic and road users, Trafikanttillstånd, TIL.
    The severity of driver fatigue in terms of line crossing: a pilot study comparing day- and night time driving in simulator2017In: European Transport Research Review, ISSN 1867-0717, E-ISSN 1866-8887, Vol. 9, no 2, article id 31Article in journal (Refereed)
    Abstract [en]

    Introduction: The overall aim of this study is to compare day-time driving with night-time driving looking at line crossings during self-reported sleepiness and long blinks. The hypothesis is that high levels of self-reported sleepiness (KSS 9) and long blink duration (>0.15 s) will be less associated with critical events during the day-time compared to night-time.

    Method: The study is based on data from a driving simulator experiment with 16 participants driving 150 km on a typical Swedish motorway scenario twice: once during daytime and once during night time. In total data from 6 segments of 4 km each equally distributed along the drive was averaged and included in the analysis. A Mixed Model Anova was used to test the effects on KSS, Blink Duration and Line Crossings with factors for Session (Day/Night) and Road segment (1–6), and participant as random. In addition, a logistic regression was used to identify when there is a risk for line crossings. Finally, the proportion of line crossings in relation to high KSS values and long blink durations was tested with Fisher’s exact test.

    Results: The results show no differences in the percentage of Line Crossings to the left during high levels of Karolinska Sleepiness Scale during daytime (33%) compare to night-time (40%). However, there was a significant difference between day and night time line crossings while the driver had long duration blinks (4% during daytime and 35% during night-time). Despite these results the most promising predictor of line crossings in each segment of 4 km/h was KSS with an Odds Ratio of 5.4 with a reference value at Karolinska Sleepiness Scale level 5.

    Conclusion: In conclusion, the results do not support the hypothesis that high levels of KSS will result in more frequent line crossings at night time compared to day time. However, the result supports the hypothesis that long blink durations are associated with more line crossings when they appear during night time than during daytime. © 2017, The Author(s).

  • 12.
    Anund, Anna
    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, Trafikanttillstånd, TIL.
    Ihlström, Jonas
    Swedish National Road and Transport Research Institute, Traffic and road users, Human-vehicle-transport system interaction.
    Bus drivers working hours and the relationship to driver fatigue2016Conference paper (Refereed)
    Abstract [en]

    Bus drivers often have irregular working hours like split shifts and their work involve high levels of stress. These factors can lead to severe sleepiness and dangerous driving. The purpose of this study is to highlight how split shifts affect sleepiness and performance during afternoon drive. The study is an experiment on real road with an equipped bus driven by professional bus drivers. The study design is a within subject design and the 18 professional bus drivers (9 males and 9 females) drove twice during afternoon; once after a day with bus driving in the morning and once after a day when they had been off duty the whole day. The hypotheses was that split shifts contribute to sleepiness during afternoon, which together can result in increased safety risks. The overall results support this hypotheses. In total five out of 18 drivers reached levels of severe sleepiness (Karolinska Sleepiness Scale ≥ 8) with an average increase in KSS of 1,94 driving in the afternoon the day that preceded with bus driving in the morning compared to the day off duty in the morning, an increase corresponding to the levels of shift workers comparing start and end of a night shift. The Psychomotor Vigilance Task showed significant increased Response Time with split shift (afternoon: 0.337s; split shift 0.347s), so did also the EEG based KDS mean/max. Blink duration also increased, even though the difference was not significant. One driver fell asleep during the drive. In addition, 12 of the 18 bus drivers reported that they in their daily work had to fight to stay awake while driving the bus at least 2-4 times per month.  Even though the study showed significant induvial differences, it is clear that the bus drivers had to fight to stay awake and countermeasures are needed in order to guarantee safe driving under split shift schedules.

  • 13.
    Anund, Anna
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Trafikanttillstånd, TIL.
    Fors, Carina
    Swedish National Road and Transport Research Institute, Traffic and road users, Trafikanttillstånd, TIL.
    Ihlström, Jonas
    Swedish National Road and Transport Research Institute, Traffic and road users, Trafikanttillstånd, TIL.
    Kecklund, Göran
    Stockholms Universitet.
    An on-road study of sleepiness in split shifts among city bus drivers2016In: Accident Analysis and Prevention, ISSN 0001-4575, E-ISSN 1879-2057Article in journal (Refereed)
    Abstract [en]

    Bus drivers often work irregular hours or split shifts and their work involves high levels of stress. These factors can lead to severe sleepiness and dangerous driving. This study examined how split shift working affects sleepiness and performance during afternoon driving. An experiment was conducted on a real road with a specially equipped regular bus driven by professional bus drivers.

    The study had a within-subject design and involved 18 professional bus drivers (9 males and 9 females) who drove on two afternoons; one on a day in which they had driven early in the morning (split shift situation) and one on a day when they had been off duty until the test (afternoon shift situation). The hypothesis tested was that split shifts contribute to sleepiness during afternoon, which can increase the safety risks. The overall results supported this hypothesis. In total, five of the 18 drivers reached levels of severe sleepiness (Karolinska Sleepiness Scale ≥8) with an average increase in KSS of 1.94 when driving in the afternoon after working a morning shift compared with being off duty in the morning. This increase corresponded to differences observed between shift workers starting and ending a night shift. The Psychomotor Vigilance Task showed significantly increased response time with split shift working (afternoon: 0.337. s; split shift 0.347. s), as did the EEG-based Karolinska Drowsiness Score mean/max. Blink duration also increased, although the difference was not significant. One driver fell asleep during the drive. In addition, 12 of the 18 bus drivers reported that in their daily work they have to fight to stay awake while driving at least 2-4 times per month. While there were strong individual differences, the study clearly showed that shift-working bus drivers struggle to stay awake and thus countermeasures are needed in order to guarantee safe driving with split shift schedules.

  • 14.
    Anund, Anna
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Trafikanttillstånd, TIL.
    Ihlström, Jonas
    Swedish National Road and Transport Research Institute, Traffic and road users, Human-vehicle-transport system interaction.
    Fors, Carina
    Swedish National Road and Transport Research Institute, Traffic and road users, Trafikanttillstånd, TIL.
    Kecklund, Göran
    Stockholms Universitet.
    Filtness, Ashleigh
    Queensland University of Technology (QUT).
    Factors associated with self-reported driver sleepiness and incidents in city bus drivers2016In: Industrial Health, ISSN 0019-8366, E-ISSN 1880-8026, Vol. 54, no 4, p. 337-346Article in journal (Refereed)
    Abstract [en]

    Driver fatigue has received increased attention during recent years and is now considered to be a major contributor to approximately 15-30% of all crashes. However, little is known about fatigue in city bus drivers. It is hypothesized that city bus drivers suffer from sleepiness, which is due to a combination of working conditions, lack of health and reduced sleep quantity and quality.

    The overall aim with the current study is to investigate if severe driver sleepiness, as indicated by subjective reports of having to fight sleep while driving, is a problem for city based bus drivers in Sweden and if so, to identify the determinants related to working conditions, health and sleep which contribute towards this. The results indicate that driver sleepiness is a problem for city bus drivers, with 19% having to fight to stay awake while driving the bus 2-3 times each week or more and nearly half experiencing this at least 2-4 times per month. In conclusion, severe sleepiness, as indicated by having to fight sleep during driving, was common among the city bus drivers. Severe sleepiness correlated with fatigue related safety risks, such as near crashes.

  • 15.
    Anund, Anna
    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.
    Stave, Christina
    Swedish National Road and Transport Research Institute, Traffic and road users, Driver and vehicle.
    Nybom, Per
    ITRA AB.
    Bälte i buss: observationsstudie av användande och resenärers perspektiv2018Report (Other academic)
    Abstract [en]

    This study aims to evaluate the seat belt usage in buses, to evaluate to what extent information about the need to use the seat belt are provided and to understand travelers' incentives of seatbelt usage. Based on the results the aim was to propose measures to increase the use of a belt when traveling by bus.

    Methods used are observational studies, discussion within focus groups and a web questionnaire. The results from the observation study showed that passenger seat belt usage was 92% in charter service, 50% in commercial liner traffic and 27% in regional liner traffic. The drivers' use was correspondingly 100% in charter service, 79% in commercial liner traffic and 85% in regional liner traffic. The results from the web questionnaire show a lower level of usage. The conclusion is that measures are needed to increase the user rate, especially in line traffic.

    In the observation study, drivers were asked if they remind the passengers to use the seat belt, in the same way the passengers were asked if they have received information when going but charter service or commercial liner traffic. In charter service, 86% experienced they had received information, in commercial liner traffic it was 61% and in regional liner traffic it was 19%. The conclusion is that there are major shortcomings in the information on the belt, which should be addressed, especially in line traffic.

    The decision to use a belt or not is individual. Factors like how old you are, what experience you're having on a safe bus, what kind of road you travel, when you travel and how you're looking at safety generally plays a part.

  • 16.
    Axelson, M.
    et al.
    Linköpings universitet.
    Ahlström, Christer
    Swedish National Road and Transport Research Institute, Traffic and road users, Human Factors in the Transport System.
    Krupenia, S.
    Scania.
    Anund, Anna
    Swedish National Road and Transport Research Institute, Traffic and road users, Human Factors in the Transport System.
    Leeuwen, W.
    Stockholms Universitet.
    Kecklund, G.
    Stockholms Universitet.
    Is it possible to adjust the driving and resting times when operating highly autonomous trucks?2018In: Journal of Sleep Research, ISSN 0962-1105, E-ISSN 1365-2869, Vol. 27Article in journal (Other academic)
  • 17.
    Barua, Shaibal
    et al.
    Mälardalens Högskola.
    Ahmed, Mobyen Uddin
    Mälardalens Högskola.
    Ahlström, Christer
    Swedish National Road and Transport Research Institute, Traffic and road users, Human Factors in the Transport System.
    Begum, Shahina
    Mälardalens Högskola.
    Automatic driver sleepiness detection using EEG, EOG and contextual information2019In: Expert systems with applications, ISSN 0957-4174, E-ISSN 1873-6793, Vol. 115, p. 121-135Article in journal (Refereed)
    Abstract [en]

    The many vehicle crashes that are caused by driver sleepiness each year advocates the development of automated driver sleepiness detection (ADSD) systems. This study proposes an automatic sleepiness classification scheme designed using data from 30 drivers who repeatedly drove in a high-fidelity driving simulator, both in alert and in sleep deprived conditions. Driver sleepiness classification was performed using four separate classifiers: k-nearest neighbours, support vector machines, case-based reasoning, and random forest, where physiological signals and contextual information were used as sleepiness indicators. The subjective Karolinska sleepiness scale (KSS) was used as target value. An extensive evaluation on multiclass and binary classifications was carried out using 10-fold cross-validation and leave-one-out validation. With 10-fold cross-validation, the support vector machine showed better performance than the other classifiers (79% accuracy for multiclass and 93% accuracy for binary classification). The effect of individual differences was also investigated, showing a 10% increase in accuracy when data from the individual being evaluated was included in the training dataset. Overall, the support vector machine was found to be the most stable classifier. The effect of adding contextual information to the physiological features improved the classification accuracy by 4% in multiclass classification and by and 5% in binary classification.

  • 18.
    Barua, Shaibal
    et al.
    Mälardalens högskola.
    Ahmed, Mobyen Uddin
    Ahlström, Christer
    Swedish National Road and Transport Research Institute, Traffic and road users, Human Factors in the Transport System.
    Begum, Shahina
    Mälardalens högskola.
    Funk, Peter
    Mälardalens högskola.
    Automated EEG Artifact Handling with Application in Driver Monitoring2017In: IEEE journal of biomedical and health informatics, ISSN 2168-2194, E-ISSN 2168-2208Article in journal (Refereed)
    Abstract [en]

    Automated analyses of electroencephalographic (EEG) signals acquired in naturalistic environments is becoming increasingly important in areas such as brain computer interfaces and behaviour science. However, the recorded EEG in such environments is often heavily contaminated by motion artifacts and eye movements. This poses new requirements on artifact handling. The objective of this paper is to present an automated EEG artifacts handling algorithm which will be used as a pre-processing step in a driver monitoring application. The algorithm, named ARTE (Automated aRTifacts handling in EEG), is based on wavelets, independent component analysis and hierarchical clustering. The algorithm is tested on a dataset obtained from a driver sleepiness study including 30 drivers and 540 30-minute 30-channel EEG recordings. The algorithm is evaluated by a clinical neurophysiologist, by quantitative criteria (signal quality index, mean square error, relative error and mean absolute error), and by demonstrating its usefulness as a pre-processing step in driver monitoring, here exemplified with driver sleepiness classification. All results are compared with a state of the art algorithm called FORCe. The quantitative and expert evaluation results show that the two algorithms are comparable and that both algorithms significantly reduce the impact of artifacts in recorded EEG signals. When artifact handling is used as a pre-processing step in driver sleepiness classification, the classification accuracy increased by 5% when using ARTE and by 2% when using FORCe. The advantage with ARTE is that it is data driven and does not rely on additional reference signals or manually defined thresholds, making it well suited for use in dynamic settings where unforeseen and rare artifacts are commonly encountered.

  • 19.
    Berg, Jessica
    et al.
    Swedish National Road and Transport Research Institute, Society, environment and transport, Mobility, actors and planning processes.
    Ihlström, Jonas
    Swedish National Road and Transport Research Institute, Traffic and road users, Human Factors in the Transport System.
    Kollektivtrafikens betydelse för mobilitet och vardagsaktiviteter hos hushåll på landsbygd: intervjustudie2017Report (Other academic)
    Abstract [en]

    On behalf of the government, VTI has the commission to implement a study on effective and innovative solutions that can enhance people’s willingness and ability to use public transport in rural areas in Sweden. This interview study is part of the commission and aims to highlight local examples of how access to transport meet the needs for mobility and participation in everyday activities among residents in rural areas. The following questions should be answered:

    1) What positive and negative aspects of living in rural areas are described?

    2) How are different modes of transport used?

    3) To what extent can public transport meet their mobility needs?

    The empirical material consists of interviews with people from 14 households living in rural areas that are close to urban neighborhoods. The rural areas are in the municipality of Kinda in Östergötland, Falun in Dalarna and Östersund in Jämtland. The results present positive and negative aspects of living in rural areas, the use of different transport modes, perceived restrictions and benefits of using public transport, the importance of the car and the informants' suggestions for solutions that could increase the use of public transport. Measures and improvements that can increase the ability to travel by public transport and reduce car trips are: public transport that connects rural areas with public transport hubs to increase access to high-demand routes; coordination between publicly funded school transport and public transport; access to shops and services at hubs; coordination between counties to offer efficient public transport to main urban centers, considering geographical proximity rather than administrative borders; and, integration of a wide variety of different mobility tools such as car-pooling, ride-sharing, public and demand-responsive public transport as well as bike rental services.

  • 20.
    Berg, Jessica
    et al.
    Swedish National Road and Transport Research Institute, Society, environment and transport, Mobility, actors and planning processes.
    Ihlström, Jonas
    Swedish National Road and Transport Research Institute, Traffic and road users, Human Factors in the Transport System.
    Henriksson, Malin
    Swedish National Road and Transport Research Institute, Society, environment and transport, Mobility, actors and planning processes.
    Bilisters användande av parkeringsanläggningar i centrala Göteborg: Orsaker, behov och konsekvenser för olika grupper2018Report (Other academic)
    Abstract [en]

    Current trends in municipal parking policy show that the number of centrally located parking spaces is reducing. About 5 000 parking spaces will disappear in Gothenburg in the next few years. The purpose of this study is to investigate the reasons why people use parking facilities in central Gothenburg. The study is based on interviews with a total of 71 motorists at three parking facilities in central Gothenburg. Ideal types have been used as an analytic tool to highlight the essence of the interviews and put them into a context. Nine ideal types were identified in the interview material that describe why people use the car and parking facilities in central Gothenburg, such as lack of alternatives to the car, stressful everyday life, seasonal use, the car as a right, to bridge long distances, pragmatism, and for tourism. The results show that incentives to drive a car and the ability to choose transport modes are influenced by everyday structures as well as attitudes and experiences associated with different transport modes and transport systems. The conclusions are that the more complex everyday life people have, the more the working life and private life will be affected by parking measures. Public transport is perceived to be inadequate and time consuming, but many also consider public transport as a good alternative to the car.

  • 21.
    Blane, Alison
    et al.
    Curtin University.
    Falkmer, Torbjörn
    Curtin University.
    Lee, Hoe C.
    Curtin University.
    Dukic Willstrand, Tania
    Swedish National Road and Transport Research Institute, Traffic and road users, Human Factors in the Transport System.
    Investigating cognitive ability and self-reported driving performance of post-stroke adults in a driving simulator2018In: Topics in Stroke Rehabilitation, ISSN 1074-9357, E-ISSN 1945-5119, Vol. 25, no 1, p. 44-53Article in journal (Refereed)
    Abstract [en]

    Background: Safe driving is a complex activity that requires calibration. This means the driver can accurately assess the level of task demand required for task completion and can accurately evaluate their driving capability. There is much debate on the calibration ability of post-stroke drivers.

    Objectives: The aim of this study was to assess the cognition, self-rated performance, and estimation of task demand in a driving simulator with post-stroke drivers and controls.

    Methods: A between-groups study design was employed, which included a post-stroke driver group and a group of similarly aged older control drivers. Both groups were observed driving in two simulator-based driving scenarios and asked to complete the NASA Task Load Index (TLX) to assess their perceived task demand and self-rate their driving performance. Participants also completed a battery of psychometric tasks to assess attention and executive function, which was used to determine whether post-stroke cognitive impairment impacted on calibration.

    Results: There was no difference in the amount of perceived task demand required to complete the driving task. Despite impairments in cognition, the post-stroke drivers were not more likely to over-estimate their driving abilities than controls. On average, the post-stroke drivers self-rated themselves more poorly than the controls and this rating was related to cognitive ability.

    Conclusion: This study suggests that post-stroke drivers may be aware of their deficits and adjust their driving behavior. Furthermore, using self-performance measures alongside a driving simulator and cognitive assessments may provide complementary fitness-to-drive assessments, as well as rehabilitation tools during post-stroke recovery.

  • 22.
    Blane, Alison
    et al.
    Curtin University.
    Lee, Hoe C.
    Curtin University.
    Falkmer, Torbjorn
    Curtin University.
    Dukic Willstrand, Tania
    Swedish National Road and Transport Research Institute, Traffic and road users, Trafikanttillstånd, TIL.
    Assessing Cognitive Ability and Simulator-Based Driving Performance in Poststroke Adults2017In: Behavioural Neurology, ISSN 0953-4180, E-ISSN 1875-8584, article id 1378308Article in journal (Refereed)
    Abstract [en]

    Driving is an important activity of daily living, which is increasingly relied upon as the population ages. It has been well-established that cognitive processes decline following a stroke and these processes may influence driving performance. There is much debate on the use of off-road neurological assessments and driving simulators as tools to predict driving performance; however, the majority of research uses unlicensed poststroke drivers, making the comparability of poststroke adults to that of a control group difficult. It stands to reason that in order to determine whether simulators and cognitive assessments can accurately assess driving performance, the baseline should be set by licenced drivers. Therefore, the aim of this study was to assess differences in cognitive ability and driving simulator performance in licensed community-dwelling poststroke drivers and controls. Two groups of licensed drivers (37 poststroke and 43 controls) were assessed using several cognitive tasks and using a driving simulator. The poststroke adults exhibited poorer cognitive ability; however, there were no differences in simulator performance between groups except that the poststroke drivers demonstrated less variability in driver headway. The application of these results as a prescreening toolbox for poststroke drivers is discussed.

  • 23.
    Blane, Alison
    et al.
    Curtin University.
    Lee, Hoe
    Curtin University.
    Falkmer, Torbjörn
    Curtin University.
    Dukic Willstrand, Tania
    Swedish National Road and Transport Research Institute, Traffic and road users, Human Factors in the Transport System.
    Cognitive ability as a predictor of task demand and self-rated driving performance in post-stroke drivers: Implications for self-regulation2018In: Journal of Transport and Health, ISSN 2214-1405, E-ISSN 2214-1405Article in journal (Refereed)
    Abstract [en]

    Driving is a highly complex task requiring multiple cognitive processes that can be adversely affected post-stroke. It is unclear how much ability post-stroke adults have to self-evaluate their driving performance. Furthermore, the impact of cognitive decline on this evaluation has not been previously investigated. The aim of this study was to investigate the perceived level of task demand involved in driving tasks, and to examine differences between perceived and observed driving performance in post-stroke drivers in comparison to a control group. A further aim of the research was to investigate the influence of cognition on self-rated driving performance. A total of 78 participants (35 post-stroke and 43 controls) were assessed using a series of cognitive tasks and were observed whilst driving. Participants were asked to rate their own driving performance and the task demand involved while driving using the NASA Task Load Index. Between group analyses were conducted to determine differences in the level of self-rated performance and task demand. Further analyses were conducted to investigate whether cognition accounted for differences in task demand or self-rated performance. Overall, the results suggested that the post-stroke drivers exhibited deficits in cognition, but they did not report increased levels of task demand when driving. Post-stroke adults also rated themselves more conservatively than the controls for on-road performance, which was associated with their reduced propensity for risk. The study suggests that cognitive deficits may influence post-stroke drivers to amend their driving behaviour, in order to bring the task demand within a manageable level. Understanding the mechanisms involved in self-rated performance and estimations of task demand can help promote accurate self-regulation practices in post-stroke drivers. Furthermore, measuring calibration may assist practitioners with assessing fitness-to-drive, as well as with tailoring driving rehabilitation. © 2018.

  • 24.
    Buendia, Ruben
    et al.
    Chalmers Tekniska Högskola.
    Forcolin, Fabio
    Chalmers Tekniska Högskola.
    Karlsson, Johan
    Autoliv Dev AB.
    Sjöqvist, Bengt-Arne
    Chalmers Tekniska Högskola.
    Anund, Anna
    Swedish National Road and Transport Research Institute, Traffic and road users, Trafikanttillstånd, TIL.
    Driver sleepiness detection in real driving situations2016In: Traffic Injury Prevention, ISSN 1538-9588, E-ISSN 1538-957X, Vol. 17, p. 222-223Article in journal (Other academic)
  • 25.
    Dukic Willstrand, Tania
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Human Factors in the Transport System.
    Anund, Anna
    Swedish National Road and Transport Research Institute, Traffic and road users, Human Factors in the Transport System.
    Pereira Cocron, Marta
    TU Chemnitz, Germany.
    Griesche, Stefan
    DLR, Germany.
    Strand, Niklas
    Swedish National Road and Transport Research Institute, Traffic and road users, Driver and vehicle.
    Troberg, Sonja
    Scania, Sweden.
    Zanovello, Luca
    Ducati, Italy.
    Collecting end-users needs regarding driver state-based automation in the ADAS&ME project2018Conference paper (Refereed)
    Abstract [en]

    The EU funded project ADAS&ME (Adaptive ADAS to support incapacitated drivers & Mitigate Effectively risks through tailor made HMI under automation) develops adapted Advanced Driver Assistance Systems. A web based survey was designed to collect the opinion of ADAS&ME end-users about automated functions that could support the driver/rider during different driving tasks. In total, 1094 persons answered the survey. The results reveal that most of the participants had heard of automated functions previously, and that about half of them also had experience using such functions. Several participants indicated concerns about data security. Furthermore, the results give an insight into how end-users perceive automation and what they see as advantages and limitations for implementation of automated driving systems corresponding to the ADAS&MEs’ goals.

  • 26.
    Dukic Willstrand, Tania
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Human Factors in the Transport System.
    Anund, Anna
    Swedish National Road and Transport Research Institute, Traffic and road users, Human Factors in the Transport System.
    Pereira Cocron, Marta
    TU Chemnitz.
    Griesche, Stefan
    DLR.
    Strand, Niklas
    Swedish National Road and Transport Research Institute, Traffic and road users, Driver and vehicle.
    Troberg, Sonja
    Scania.
    Zanovello, Luca
    Ducati.
    Nikolau, Stella
    CERTH.
    Collecting end-user needs regarding driver statebased automation in ADAS&ME project2018Conference paper (Other academic)
  • 27.
    Dukic Willstrand, Tania
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Human Factors in the Transport System.
    Broberg, Thomas
    Chalmers Tekniska Högskola.
    Selander, Helena
    Göteborgs Universitet.
    Driving Characteristics of Older Drivers and Their Relationship to the Useful Field of View Test2017In: Gerontology, ISSN 0304-324X, E-ISSN 1423-0003, Vol. 63, no 2, p. 180-188Article in journal (Refereed)
    Abstract [en]

    To maintain the mobility of older people in later life, it is essential to sustain their autonomy; however, driving is a complex task, requiring a large range of visual, psychomotor and cognitive abilities. Subsequently, a key issue is to measure and evaluate the fitness to drive of older drivers. Several methods have been proposed, among them the useful field of view (UFOV) test.

    The present study aimed to identify driving characteristics in older drivers and the relationship between the UFOV test and the on-road driving results. A total of 80 drivers aged 70 years or older performed both the UFOV test and the on-road driving assessment. The ‘B On-Road' (Behaviour On-Road) protocol was used for the fitness-to-drive assessment.

    ‘Driving too fast' was the item reported most often during the on-road assessment, followed by problems with the manual gearbox and ‘attention to signs, road lines and traffic lights'. Overall, the results showed that the older the driver, the more errors were reported during the on-road driving assessment, as well as the slower the performance on the UFOV test. A significant relationship between the total number of on-road errors, as measured by the B On-Road protocol, and the UFOV 3, which stresses the capacity of selective attention, was found.The recommendation is still to use on-road driving assessment to fully assess fitness to drive for older drivers whose ability to drive requires assessment. However, to supplement this, the UFOV test, in particular the UFOV 3, is a valuable complement in selecting those drivers requiring to be assessed.

  • 28.
    Forcolin, Fabio
    et al.
    Chalmers Tekniska Högskola.
    Buendia, Ruben
    Chalmers Tekniska Högskola.
    Candefjord, Stefan
    Chalmers Tekniska Högskola.
    Karlsson, Johan
    Autoliv Development AB.
    Sjoqvist, Bengt Arne
    Chalmers Tekniska Högskola.
    Anund, Anna
    Swedish National Road and Transport Research Institute, Traffic and road users, Human Factors in the Transport System.
    Comparison of outlier heartbeat identification and spectral transformation strategies for deriving heart rate variability indices for drivers at different stages of sleepiness2018In: Traffic Injury Prevention, ISSN 1538-9588, E-ISSN 1538-957X, Vol. 19, p. S112-S119Article in journal (Refereed)
    Abstract [en]

    Objective: Appropriate preprocessing for detecting and removing outlier heartbeats and spectral transformation is essential for deriving heart rate variability (HRV) indices from cardiac monitoring data with high accuracy. The objective of this study is to evaluate agreement between standard preprocessing methods for cardiac monitoring data used to detect outlier heartbeats and perform spectral transformation, in relation to estimating HRV indices for drivers at different stages of sleepiness.

    Methods: The study analyzed more than 3,500 5-min driving epochs from 76 drivers on a public motorway in Sweden. Electrocardiography (ECG) data were recorded in 3 studies designed to evaluate the physiological differences between awake and sleepy drivers. The Pan-Tompkins algorithm was used for peak detection of heartbeats from ECG data. Two standard methods were used for identifying outlier heartbeats: (1) percentage change (PC), where outliers were defined as interbeat interval deviating >30% from the mean of the 4 previous intervals, and (2) standard deviation (SD), where outliers were defined as interbeat interval deviating >4 SD from the mean interval duration in the current epoch. Three standard methods were used for spectral transformation, which is needed for deriving HRV indices in the frequency domain; these methods were (1) the Fourier transform; (2) an autoregressive model; and (3) the Lomb-Scargle periodogram. The preprocessing methods were compared quantitatively and by assessing agreement between estimations of 13 common HRV indices using Bland-Altman plots and paired Student's t-tests.

    Results: The PC method detected more than 4times as many outliers (0.28%) than SD (0.065%). Most HRV indices derived using different preprocessing methods exhibited significant systematic (P <.05) and substantial random variations.

    Conclusions: The standard preprocessing methods for HRV data for outlier heartbeat detection and spectral transformation show low levels of agreement. This finding implies that, prior to designing algorithms for detection of sleepy drivers based on HRV analysis, the impact of different preprocessing methods and combinations thereof on driver sleepiness assessment needs to be studied.

  • 29.
    Fors, Carina
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Trafikanttillstånd, TIL.
    Ahlström, Christer
    Swedish National Road and Transport Research Institute, Traffic and road users, Trafikanttillstånd, TIL.
    Anund, Anna
    Swedish National Road and Transport Research Institute, Traffic and road users, Trafikanttillstånd, TIL.
    A comparison of driver sleepiness in the simulator and on the real road2016In: Journal of Transportation Safety and Security, ISSN 1943-9962, p. 1-16Article in journal (Refereed)
    Abstract [en]

    For safety reasons as well as for experimental control, driver sleepiness experiments are often run in simulators. The aim of this study is to compare the development of driver sleepiness in an advanced driving simulator experiment with real road driving. Sixteen drivers participated in the experiment, which included daytime and night-time driving on a real motorway and in an advanced driving simulator.

    The results showed that there were significantly higher levels of Karolinska Sleepiness Scale (KSS) ratings, longer blink durations, lower percentage of gazes directed toward the road center (PRC), and higher speed, in the simulator compared to the real road. The pattern of change with task progression was consistent between simulator driving and real road driving for all investigated variables, that is, speed, KSS, line crossings, blink duration, and PRC. However, the relative differences were higher during daytime compared to night-time driving.

    Results from a questionnaire showed that it was more boring and more demanding to stay alert in the simulator. In conclusion, the development of sleepiness over time is similar in the simulator as compared to the real road, though the absolute sleepiness level is higher in the simulator.

  • 30.
    Fors, Carina
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Human Factors in the Transport System.
    Johansen, Trond Cato
    Ramböll.
    Lundkvist, Sven-Olof
    Nygårdhs, Sara
    Swedish National Road and Transport Research Institute, Traffic and road users, Human Factors in the Transport System.
    Nordic certification system for road marking materials: version 5:20182018Report (Other academic)
    Abstract [en]

    A Nordic certification system for road marking materials was introduced in 2015. The system is based on documented performance measurements of material samples applied on test fields on public roads. From 2016, the certification system includes both flat (type I) and structured/profiled (type II) markings. Since 2017 the certification system also includes antiskid materials (a material with enhanced friction). From 2018 the certification system will also include temporary markings (Denmark only), and inlaid markings (Norway only).

    Material tests are carried out at two test sites: one in Norway and one in Denmark. The tests fields are situated on public roads and the tested materials are thus exposed to real traffic conditions and to weather conditions representative for the Nordic countries. The materials are followed up by performance measurements during one or two years. The certification includes requirements on coefficient of retroreflected luminance RL under dry and wet conditions, luminance coefficient under diffuse illumination Qd, friction and colour coordinates. The number of wheel passages is measured at the test sites annually. The certification system includes material identification, which allows for future material sampling and analysis.

    The certification system is based on the European standards EN 1824 Road marking materials Road trials, EN 1436 Road marking materials Road marking performance for road users, and EN 12802 Road marking materials Laboratory methods for identification.

    The report describes the certification system and how it is applied in the Nordic countries. Procedures and methods that are used for application of materials and performance measurements are specified.

  • 31.
    Fors, Carina
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Trafikanttillstånd, TIL.
    Lundkvist, Sven-Olof
    Swedish National Road and Transport Research Institute.
    Mätning av friktion på vägmarkering: jämförelse av olika metoder samt utveckling av modell för mobil mätning2016Report (Other academic)
    Abstract [en]

    For road markings, there is a performance requirement regarding friction, which is given in units obtained with handheld instruments. Such instruments are not suitable for assessment of friction on longer stretches of road, since it would be too time consuming and expensive. In order to be able to monitor a large road network and to assess whether the performance requirements are fulfilled, mobile measurement methods are needed, i.e. methods based on instruments mounted on vehicles. Besides, the friction that occurs between the tyres of a vehicle and the road surface is speed dependent. Handheld instruments reflect the friction that occurs in low speeds, while from a traffic safety perspective, friction in higher speeds is most relevant.

    The present report describes the results from two studies about methods for mobile assessment or estimation of road marking friction. In the first study, three different mobile methods, Road Friction Tester (RFT), Traction Watcher One (TWO) and Road Marking Tester (RMT), were compared to the handheld method Portable Friction Tester (PFT). In the second study, a prediction model for friction in higher speeds was developed, based on measurements of the coefficient of retroreflected luminance and the texture of the road marking.

    The first study showed that the different methods give different results, which is expected since the physical quantity coefficient of friction does not have a unique definition but is dependent on the properties of the instrument. In lower speeds, there were significant relationships between PFT and RFT, and between PFT and TWO (correlation coefficient 0,89 and 0,86, respectively). The relationships between PFT and RMT were somewhat weaker, although significant (correlation coefficients 0,65–0,71). In higher speeds, there was a significant relationship between RFT and TWO (correlation coefficient 0,80). The relationships between RMT and RFT, and between RMT and TWO, were weaker but significant (correlation coefficients 0,86–0,89). TWO gave lower friction values than the other methods. Measurement speed had an influence on the results obtained with RFT and TWO.

    In the second study, TWO was used as a reference when developing a prediction model for friction in higher speeds. The results showed that friction to some extent can be predicted from the coefficient of retroreflected luminance and the texture of the marking, but that the relationship is not strong enough for the model to be applicable. A limitation of the study is that there is no standardized method for measurement of road marking friction in higher speeds available. The reference method used, TWO, is developed for friction assessment of road surfaces and not for road markings, which implies that the ability of the instrument to assess road marking friction is somewhat uncertain.

  • 32.
    Fors, Carina
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Trafikanttillstånd, TIL.
    Lundkvist, Sven-Olof
    Englundh, Stig
    Mobil mätning av vägbelysning2017Report (Other academic)
    Abstract [en]

    For most types of road equipment there are regulations that set the performance requirements. For example, a road marking must have a minimum retroreflectivity for it to have sufficient visibility. Regarding road lighting there are multiple performance requirements in the Swedish Transport Administration's requirements for road and street design (VGU), including requirements for allowed glare, demands on shielding, illuminance and road surface luminance. On most roads and streets, the luminance requirement is the most important parameter, not least because this is important for the possibility of detecting pedestrians.

    For a requirement in the regulations to be meaningful, it is important that it is possible to check if the requirements are met. However, luminance measurements are complicated and susceptible to interference from ambient light sources.

    The purpose of this study was to develop a prototype of an instrument which enables fast mobile measurements of road surface luminance without the risk of interference from other traffic.

    Completed tests with the instrument have shown that the measurement of road surface luminance on longer sections can be performed, without light interference from other traffic. The measurements are also relatively rapid and requires a minimum of manual data processing. The measurement system additionally has good accuracy which makes it suitable for condition assessment of road lighting.

  • 33.
    Fors, Carina
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Trafikanttillstånd, TIL.
    Yahya, Mohammad-Reza
    Swedish National Road and Transport Research Institute, Infrastructure, Measurement technology and engineering workshop.
    Lundkvist, Sven-Olof
    Intermittenta, heldragna och profilerade vägmarkeringars funktion över tid2016Report (Other academic)
    Abstract [en]

    Paved public roads usually have longitudinal road markings, which can be of different types. Two-lane roads should have a 10 or 15 cm wide broken edge line, but a continuous edge line can be used in order to enhance visibility. If the annual average daily traffic (AADT) is ≥ 2000 the edge lines must be wet-night visible, which is attained by creating a so-called profiled marking.

    The aim of the project was to investigate whether there is a difference in durability between a broken and a continuous edge line, and to investigate whether there is a difference in performance and durability between different types of profiled markings. In the first part of the project, broken and continuous edge lines were applied on a public two-lane road. The performance of the markings was followed up by annual measurements of retroreflectivity RL and luminance coefficient Qd for four years. In the second part of the project, a test field with six different types of markings - one without and five with profile – were applied on a public road.

    Follow-up measurements of retroreflectivity RL on dry as well as on wet markings, and luminance coefficient Qd in dry conditions were carried out after one and two years. No difference in durability between broken and continuous edge lines was shown. Regarding profiled markings, a road marking with an embossed pattern had the best performance with respect to all three performance parameters. Profiled markings with diagonal squares (“stairs”) had better performance than markings with transversal lines.

  • 34.
    Ihlström, Jonas
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Human Factors in the Transport System. K2.
    Anund, Anna
    Swedish National Road and Transport Research Institute, Traffic and road users, Human Factors in the Transport System.
    Scholten, Christina
    Malmö Högskola.
    Johansson, Sofie
    Malmö Högskola.
    Hot och våld mot bussförare och tågvärdar2017Report (Other academic)
    Abstract [sv]

    I studien har befintlig statistik över inrapporterat hot och våld bland bussförare och tågvärdar analyserats. Den kvalitativ ansatsen i studien bygger på intervjuer med medarbetare och chefer i trafikföretagen. Sammanlagt har 29 bussförare och tågvärdar intervjuats (16 tågvärdar och 12 bussförare), samt 7 chefer i olika befattningar i de två bolagen. Med detta som utgångspunkt har ett antal potentiala åtgärder identiferats och kategoriserats som aktörssamverkan eller organisationsutveckling. Aktörssamverkan handlar om att utveckla samverkan och tydligheten mot kund i avgörande frågor som biljettaviseringer etc. Det är framförallt samverkan mellan trafikföretag och kollektivtrafikmyndighet som är avgörande. Självklart ska även förarna vara med i denna dialog. Organisationsutveckling handlar om att ta fram, tydligt kommunicera och följa upp riktlinjer till förare och tågvärdare. Detta är framförallt viktigt när det gäller färdbeviskontroll. Det handlar även om att förbättra tillbudsrapporteringen och de förutsättningar och vilkor som desas omges med. Det måste vara tydligt att rapporteringen är viktigt, vad som ska rapporteras, när och hur, men även vad den leder till. Vidare är värderingar och värdegrundsarbete en sannolikt en viktig fråga att jobba med. I detta ingår att ha en gemensam sund företagskultur, en tydlighet i vilken roll medarbetare har i olika situationer, diskrimineringsgrunder etc. Medarbetarperspektiv är en viktigt dimension. Att se till att de förare och tågvärdar har en repetoar med svar till de som inte vill visa giligt färdbevis förväntas vara en lämplig åtgärd.

  • 35.
    Ihlström, Jonas
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Trafikanttillstånd, TIL.
    Kecklund, Göran
    Stockholms Universitet.
    Anund, Anna
    Swedish National Road and Transport Research Institute, Traffic and road users, Trafikanttillstånd, TIL.
    Split-shift work in relation to stress, health and psychosocial work factors among bus drivers2017In: Work: A journal of Prevention, Assesment and rehabilitation, ISSN 1051-9815, E-ISSN 1875-9270, Vol. 56, no 4, p. 531-538Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: Shift work has been associated with poor health, sleep and fatigue problems and low satisfaction with working hours. However, one type of shift working, namely split shifts, have received little attention.

    OBJECTIVE: This study examined stress, health and psychosocial aspects of split-shift schedules among bus drivers in urban transport.

    METHODS: A questionnaire was distributed to drivers working more than 70% of full time which 235 drivers in total answered.

    RESULTS: In general, drivers working split-shift schedules (n = 146) did not differ from drivers not working such shifts (n = 83) as regards any of the outcome variables that were studied. However, when individual perceptions towards split-shift schedules were taken into account, a different picture appeared. Bus drivers who reported problems working split shifts (36%) reported poorer health, higher perceived stress, working hours interfering with social life, lower sleep quality, more persistent fatigue and lower general work satisfaction than those who did not view split shifts as a problem. Moreover, drivers who reported problems with split shifts also perceived lower possibilities to influence working hours, indicating lower work time control.

    CONCLUSIONS: This study indicates that split shifts were not associated with increased stress, poorer health and adverse psychosocial work factors for the entire study sample. However, the results showed that individual differences were important and approximately one third of the drivers reported problems with split shifts, which in turn was associated with stress, poor health and negative psychosocial work conditions. More research is needed to understand the individual and organizational determinants of tolerance to split shifts.

  • 36.
    Jansson, Andreas
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Driving Simulation and Visualization.
    Ahlström, Christer
    Swedish National Road and Transport Research Institute, Traffic and road users, Human Factors in the Transport System.
    Linking gaze tracking with a simulated world2017Report (Other academic)
    Abstract [en]

    The main focus of this study was to develop a software able to link eye tracking data to simulator data, making it possible to automatically detect what the driver is looking at in the simulated world. This was achieved by merging data from a SmartEye system with data from the simulator. Thereby realtime visualisation of where the driver is looking is facilitated, and what the driver is targeting can be shown to the test leader to trigger events in the scenarios, etc. This also facilitates automatic gaze annotations that can be used in subsequent analyses when studying visual behaviour.

    The developed software, VIMSI, is responsible for collecting eye tracking data from SmartEye, filter and aggregate this data with data from the simulation and then send processed data to the graphics to visualize the result. The software was tested in one of VTI’s driving simulators. This initial testing of VIMSI showed that the software is capable of visualising what the driver is looking at in real time. The software also makes it possible to log data from the test drives which can be useful when studying driver behaviour. To improve the functionality of VIMSI, it is necessary to consider using UDP instead of IPC when directing data from the VIMSI software to the graphics engine VISIR. This will enable the use of another software, ScenarioReplay, developed at VTI for replaying test drives. A proper configuration and calibration of the SmartEye cameras is necessary to achieve high quality of the data from the SmartEye Pro software, which is a precondition for VIMSI.

  • 37.
    Johansen, Trond Cato
    et al.
    Ramböll.
    Fors, Carina
    Swedish National Road and Transport Research Institute, Traffic and road users, Human Factors in the Transport System.
    Method description – assessment of road marking materials used in contracts: Nordic certification system for road marking materials2018Report (Other academic)
    Abstract [en]

    A Nordic certification system for road marking materials was introduced in 2015. In the first stage, the certification system applies to the countries of Denmark, Norway and Sweden. In these countries, a documented product approval will be required in order to use a road marking material on roads managed by the national road authorities. Product approval will be based on monitored and documented performance measurements of material samples applied on test fields on public roads.

    In order to be able to assess whether the (approved) road marking materials that are specified in contracts with a national road authority correspond to the materials that are applied on the roads, an assessment system will be introduced. The present report describes this assessment system.

    The assessment system prescribes that material samples shall be taken when road marking materials are applied on the roads. A selection of the samples will then be sent to an accredited laboratory for analysis. The report describes how the material samples are selected, collected and analysed, and how the result is reported. It also describes the contractor’s responsibilities related to sample collection and the required competences of the assessment organization.

  • 38.
    Johansen, Trond Cato
    et al.
    Ramböll.
    Fors, Carina
    Swedish National Road and Transport Research Institute, Traffic and road users, Human Factors in the Transport System.
    Kjellman, Erik
    Swedish National Road and Transport Research Institute, Traffic and road users, Human Factors in the Transport System.
    Nordic certification of road marking materials in Denmark 2015–20172018Report (Other academic)
    Abstract [en]

    A Nordic certification system for road marking materials was introduced in 2015. In the first stage, the certification system applies to the countries of Denmark, Norway and Sweden. In these countries, a documented product approval will be required in order to use a road marking material on roads managed by the national road authorities. Product approval will be based on monitored and documented performance measurements of material samples applied on test fields on public roads.

    The first round of material tests in Denmark started in autumn 2015. In all, 32 materials, out of which 24 were for certification and 8 for manufacturer’s internal test, were applied at the Danish test site in Hornbæk. In 2016, a new test site was established close to Gørlev, where another 22 materials were applied, 20 for certification and 2 for manufacturer’s internal test.

    The present report documents the follow-up performance measurements that were carried out in 2017, i.e. one year follow-up measurements for materials applied in 2016 and two years follow-up measurements for materials applied in 2015. The performance parameters include the coefficient of retroreflected luminance (RL) under dry and wet conditions, the luminance coefficient under diffuse illumination (Qd), the friction, and the chromaticity in daylight.

  • 39.
    Johansen, Trond Cato
    et al.
    Ramböll.
    Fors, Carina
    Swedish National Road and Transport Research Institute, Traffic and road users, Human Factors in the Transport System.
    Kjellman, Erik
    Swedish National Road and Transport Research Institute, Traffic and road users, Human Factors in the Transport System.
    Nordic certification of road marking materials in Norway and Sweden 2015–20172018Report (Other academic)
    Abstract [en]

    A Nordic certification system for road marking materials was introduced in 2015. In the first stage, the certification system applies to the countries of Denmark, Norway and Sweden. In these countries, a documented product approval will be required in order to use a road marking material on roads managed by the national road authorities. Product approval will be based on monitored and documented performance measurements of material samples applied on test fields on public roads.

    The first round of material tests in Sweden started in May 2015. In all, 81 materials, out of which 78 were for certification and 3 for manufacturer’s internal test, were applied at the Swedish test site north of Sunne, in the west of Sweden. In 2016, another 72 materials were applied for certification at the Swedish test site.

    The present report documents the follow-up performance measurements that were carried out in 2017, i.e. one-year follow-up measurements for materials applied in 2016 and two years follow-up measurements for materials applied in 2015. The performance parameters include the coefficient of retroreflected luminance (RL) under dry and wet conditions, the luminance coefficient under diffuse illumination (Qd), the friction, the chromaticity in daylight, and the chromaticity of retroreflected light (yellow materials, only).

  • 40.
    Johansen, Trond Cato
    et al.
    Ramböll.
    Fors, Carina
    Swedish National Road and Transport Research Institute, Traffic and road users, Trafikanttillstånd, TIL.
    Nygårdhs, Sara
    Swedish National Road and Transport Research Institute, Traffic and road users, Trafikanttillstånd, TIL.
    Lundkvist, Sven-Olof
    Nordic certification of road marking materials in Denmark 2015–20162016Report (Other academic)
    Abstract [en]

    A Nordic certification system for road marking materials was introduced in 2015. In the first stage, the certification system applies to Denmark, Norway and Sweden. In these countries, a documented product approval will be required in order to use a road marking material on roads managed by the national road authorities. Product approval will be based on monitored and documented performance measurements of material samples applied on test fields on public roads.

    Today, the certification system includes two test sites: one in Sweden and one in Denmark. However, the present report only deals with the certification in Denmark; the results from the Swedish test site will be presented in another report. The first round of material application took place in 2015, while follow-measurements were carried out around one year later, in 2016. At this point in time, the wheel passage classes P0, P1, P2 and P3 were reached at the Danish test site. In other words, the report presents which materials were certified for the mentioned P classes in 2016.

  • 41.
    Johansen, Trond Cato
    et al.
    Ramböll.
    Fors, Carina
    Swedish National Road and Transport Research Institute, Traffic and road users, Trafikanttillstånd, TIL.
    Nygårdhs, Sara
    Swedish National Road and Transport Research Institute, Traffic and road users, Trafikanttillstånd, TIL.
    Lundkvist, Sven-Olof
    Nordic certification of road marking materials in Sweden 2015−20162016Report (Other academic)
    Abstract [en]

    A Nordic certification system for road marking materials was introduced in 2015. In the first stage, the certification system applies to the countries of Denmark, Norway and Sweden. In these countries, a documented product approval will be required in order to use a road marking material on roads managed by the national road authorities. Product approval will be based on monitored and documented performance measurements of material samples applied on test fields on public roads.

    Today, the certification system includes two test sites: one in Sweden and one in Denmark. However, the present report only deals with the certification in Sweden. The first round of material application took place in 2015, while follow-up measurements were carried out around one year later, in 2016. At this point in time, the wheel passage classes P0, P1, P2, P3 and P4 were reached at the Swedish test site. In other words, the report presents which materials were certified for the mentioned P-classes in 2016.

  • 42.
    Jopson, Ann
    et al.
    ITS Leeds.
    Batley, Richard
    ITS Leeds.
    Tanner, Reto
    ITS Leeds.
    Olstam, Johan
    Swedish National Road and Transport Research Institute, Society, environment and transport, Traffic analysis and logistics.
    Ihlström, Jonas
    Swedish National Road and Transport Research Institute, Traffic and road users, Trafikanttillstånd, TIL.
    Jamson, Samantha
    ITS Leeds.
    Nellthorp, John
    ITS Leeds.
    Carsten, Oliver
    ITS Leeds.
    Scenarios for green driving support systems2016Report (Other academic)
    Abstract [en]

    This work package developed a range of future scenarios with varying degrees of green driver support, considering technological, human and political perspectives. These scenarios will be used in the microsimulation (WP53) and the scaling-up (WP54). Focus groups and a survey were carried out, as well as aggregation to the vehicle market. In the focus group discussions, eco-driving systems were valued for heavy vehicle, fleet markets and individual drivers, with commercial buyers sensitive to costs and HMI, but private buyers concerned with engine type and fuel economy – both relating to costs. In the survey, purchasers indicated that they were willing to pay substantially more for a built in advice system as compared with a mobile phone app.

  • 43.
    Jägerbrand, Annika
    et al.
    Swedish National Road and Transport Research Institute, Society, environment and transport, Environment.
    Antonson, Hans
    Swedish National Road and Transport Research Institute, Society, environment and transport, Mobility, actors and planning processes.
    Ahlström, Christer
    Swedish National Road and Transport Research Institute, Traffic and road users, Human Factors in the Transport System.
    Speed reduction effects over distance of animal-vehicle collision countermeasures: a driving simulator study2018In: European Transport Research Review, ISSN 1867-0717, E-ISSN 1866-8887, Vol. 10, no 2, article id 40Article in journal (Refereed)
    Abstract [en]

    Purpose: This study examined if speed reduction effects from animal-vehicle collision (AVC) countermeasures are merely local or do extend to a wider area, and what implications the results have on road planning practice regarding AVCs.

    Methods: Twenty-five drivers drove repeatedly on a 9-km long road stretch in a high-fidelity driving simulator. The development of vehicle speed in the surrounding of an automatic speed camera, a wildlife warning sign and a radio message, were investigated in a full factorial within-subject experiment. The factors wildlife fence (with/without) and forest (dense/open landscape) were also included.

    Results: The radio warning message had the largest influence on vehicle speed with a speed reduction of 8 km/h that lasted beyond 1 km and 2 km after the implementation. Eighty-eight per cent of the drivers reported being made extra aware of AVC due to the radio message, which was also associated with stress, insecurity and unsafety. The warning sign reduced vehicle speed by 1.5 km/h, but speed reductions were not significantly reduced 1 km after the implementation. Only 8 % of the drivers felt insecure/unsafe after passing the wildlife warning sign, explaining its limited impact on speed. There were no main effects of the automatic speed camera on vehicle speed at longer distances after implementation.

    Conclusions: We recommend that AVC countermeasures should be of various design, occur at various segments along the road, and preferably be adaptive and geo-localized to minimize habituation effects on drivers.

  • 44.
    Kircher, Katja
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Trafikanttillstånd, TIL.
    Ahlström, Christer
    Swedish National Road and Transport Research Institute, Traffic and road users, Trafikanttillstånd, TIL.
    Evaluation of methods for the assessment of attention while driving2017In: Accident Analysis and Prevention, ISSN 0001-4575, E-ISSN 1879-2057Article in journal (Refereed)
    Abstract [en]

    The ability to assess the current attentional state of the driver is important for many aspects of driving, not least in the field of partial automation for transfer of control between vehicle and driver. Knowledge about the driver's attentional state is also necessary for the assessment of the effects of additional tasks on attention. The objective of this paper is to evaluate different methods that can be used to assess attention, first theoretically, and then empirically in a controlled field study and in the laboratory.

    Six driving instructors participated in all experimental conditions of the study, delivering within-subjects data for all tested methods. Additional participants were recruited for some of the conditions. The test route consisted of 14. km of motorway with low to moderate traffic, which was driven three times per participant per condition. The on-road conditions were: baseline, driving with eye tracking and self-paced visual occlusion, and driving while thinking aloud. The laboratory conditions were: Describing how attention should be distributed on a motorway, and thinking aloud while watching a video from the baseline drive.

    The results show that visual occlusion, especially in combination with eye tracking, was appropriate for assessing spare capacity. The think aloud protocol was appropriate to gain insight about the driver's actual mental representation of the situation at hand. Expert judgement in the laboratory was not reliable for the assessment of drivers' attentional distribution in traffic. Across all assessment techniques, it is evident that meaningful assessment of attention in a dynamic traffic situation can only be achieved when the infrastructure layout, surrounding road users, and intended manoeuvres are taken into account. This requires advanced instrumentation of the vehicle, and subsequent data reduction, analysis and interpretation are demanding. In conclusion, driver attention assessment in real traffic is a complex task, but a combination of visual occlusion, eye tracking and thinking aloud is a promising combination of methods to come further on the way. .

  • 45.
    Kircher, Katja
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Trafikanttillstånd, TIL.
    Ahlström, Christer
    Swedish National Road and Transport Research Institute, Traffic and road users, Trafikanttillstånd, TIL.
    Evaluation of methods for the assessment of attention while driving2016Conference paper (Refereed)
    Abstract [en]

    The ability to assess the current attentional state of the driver is important for many aspects of driving, not least in the field of automation. Knowledge about the driver’s attentional state is necessary for the assessment of the effects of additional tasks on attention, and for the transfer of control between vehicle and driver. Therefore, different methods that can be used to assess attention, were evaluated theoretically and then empirically in a controlled field study and in the laboratory.

    Six driving instructors participated in all experimental conditions of the study, delivering within-subjects data for all tested methods. Additional participants were recruited for some of the conditions. The test route consisted of 14 km of motorway with low to moderate traffic, which was driven three times per participant per condition. The on-road conditions were: baseline, driving with eye tracking and self-paced visual occlusion, and driving while thinking aloud. The laboratory conditions were: Describing how attention should be distributed on a motorway, giving a written percentage distribution for a motorway situation, and thinking aloud while watching a video from the baseline drive. For the analysis the on-road data were split into manoeuvres. Attention was distributed differently depending on manoeuvre type, which was evident from both eye tracking, occlusion, the think aloud protocol and the lab-based methods, therefore it is recommended to consider the type of manoeuvre when making attention assessments. The visual occlusion method is a valuable tool to assess spare visual capacity. Especially in combination with eye tracking, and in comparison with “baseline” driving it shows which glances are experienced as containing necessary information, and which glances are “spare” glances. The think aloud method is a meaningful tool to approach the driver’s actual mental representation of the situation at hand. However, this method should be used with caution, as talking about one’s attentional distribution in fact changes one’s glance behaviour in comparison to baseline driving. Expert judgements in the laboratory did not turn out to be a reliable and useful method for the assessment of drivers’ attentional distribution in traffic. This may be due to difficulties in verbally accessing procedural knowledge.

    For successful attention assessment in a dynamic traffic situation it is important to have access to information about the manoeuvres made by the driver in relation to other vehicles on the road. Also, knowledge about the road layout, speed limit etc. should be incorporated into the assessment. All this requires a rather advanced instrumentation of the experimental vehicle. In addition, data reduction, analysis and interpretation are demanding. To summarise, driver attention assessment in real traffic is a complex task, but a triangulation of visual occlusion, eye tracking and thinking aloud is a promising combination of methods to come further on the way.

  • 46.
    Kircher, Katja
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Trafikanttillstånd, TIL.
    Ahlström, Christer
    Swedish National Road and Transport Research Institute, Traffic and road users, Trafikanttillstånd, TIL.
    Minimum Required Attention: A Human-Centered Approach to Driver Inattention2017In: Human Factors, ISSN 0018-7208, E-ISSN 1547-8181, Vol. 59, no 3, p. 471-484Article in journal (Refereed)
    Abstract [en]

    Objective: To propose a driver attention theory based on the notion of driving as a satisficing and partially self-paced task and, within this framework, present a definition for driver inattention.

    Background: Many definitions of driver inattention and distraction have been proposed, but they are difficult to operationalize, and they are either unreasonably strict and inflexible or suffer from hindsight bias.

    Method: Existing definitions of driver distraction are reviewed and their shortcomings identified. We then present the minimum required attention (MiRA) theory to overcome these shortcomings. Suggestions on how to operationalize MiRA are also presented.

    Results: MiRA describes which role the attention of the driver plays in the shared "situation awareness of the traffic system." A driver is considered attentive when sampling sufficient information to meet the demands of the system, namely, that he or she fulfills the preconditions to be able to form and maintain a good enough mental representation of the situation. A driver should only be considered inattentive when information sampling is not sufficient, regardless of whether the driver is concurrently executing an additional task or not.

    Conclusions: The MiRA theory builds on well-established driver attention theories. It goes beyond available driver distraction definitions by first defining what a driver needs to be attentive to, being free from hindsight bias, and allowing the driver to adapt to the current demands of the traffic situation through satisficing and self-pacing. MiRA has the potential to provide the stepping stone for unbiased and operationalizable inattention detection and classification.

  • 47.
    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.

  • 48.
    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.

  • 49.
    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.

  • 50.
    Kircher, Katja
    et al.
    Swedish National Road and Transport Research Institute, Traffic and road users, Trafikanttillstånd, TIL.
    Nygårdhs, Sara
    Swedish National Road and Transport Research Institute, Traffic and road users, Trafikanttillstånd, TIL.
    Ihlström, Jonas
    Swedish National Road and Transport Research Institute, Traffic and road users, Trafikanttillstånd, TIL.
    Ahlström, Christer
    Swedish National Road and Transport Research Institute, Traffic and road users, Trafikanttillstånd, TIL.
    Cyklisters interaktion med extrautrustning, infrastrukturen och andra trafikanter: En semi-kontrollerad fältstudie2017Report (Other academic)
    Abstract [en]

    How cyclists interact with the infrastructure, and how they integrate the handling of additional tasks, is dependent on the surrounding traffic situation and the cyclists’ characteristics. To study these relationships, a semi-controlled field study was conducted with 41 cyclists, who belonged to different cyclist groups with respect to their usual travel speed during transport trips. Speed, gaze direction and tactical behaviour like choice of path and the interaction with incoming text messages was logged, while the cyclists travelled along a six kilometre long route in the inner city of Linköping. Interviews and think aloud protocols, as well as video recordings from different perspectives were employed as well.

    It was common that the cyclists ignored incoming text messages, a third was answered directly while cycling. The texting while cycling did not lead to attentional decrements, because the cyclists adapted their interaction with the telephone to the prevailing traffic situation. The interaction with the phone did not differ substantially between cyclist groups. However, the design of the infrastructure affected the cyclist groups differently, where faster cyclists were delayed more in cases where the infrastructure necessitated stops regardless of the traffic situation, while comfort cyclists were the group delayed most in a roundabout that was difficult to interpret. Cycling on the pavement was common, and it mainly reflects the insecurity experienced in mixed traffic with cars. It is important to consider the different needs of different cyclist types when planning the road infrastructure, to avoid irritation, insecurity and conflicts.

12 1 - 50 of 74
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf