Endre søk
Begrens søket
12 1 - 50 of 77
RefereraExporteraLink til resultatlisten
Permanent link
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Treff pr side
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Forfatter A-Ø
  • Forfatter Ø-A
  • Tittel A-Ø
  • Tittel Ø-A
  • Type publikasjon A-Ø
  • Type publikasjon Ø-A
  • Eldste først
  • Nyeste først
  • Skapad (Eldste først)
  • Skapad (Nyeste først)
  • Senast uppdaterad (Eldste først)
  • Senast uppdaterad (Nyeste først)
  • Disputationsdatum (tidligste først)
  • Disputationsdatum (siste først)
  • Standard (Relevans)
  • Forfatter A-Ø
  • Forfatter Ø-A
  • Tittel A-Ø
  • Tittel Ø-A
  • Type publikasjon A-Ø
  • Type publikasjon Ø-A
  • Eldste først
  • Nyeste først
  • Skapad (Eldste først)
  • Skapad (Nyeste først)
  • Senast uppdaterad (Eldste først)
  • Senast uppdaterad (Nyeste først)
  • Disputationsdatum (tidligste først)
  • Disputationsdatum (siste først)
Merk
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 1.
    Ahlström, Christer
    et al.
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Andersson, Jan
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Anund, Anna
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Börjesson, Emma
    Scania.
    Johansson, Hanna
    Scania.
    Johnsson, Johanna
    Scania.
    Detecting sleepiness by Optalert: final report2010Rapport (Annet vitenskapelig)
    Abstract [en]

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

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

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

  • 2.
    Ahlström, Christer
    et al.
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Trafikanttillstånd, TIL.
    Anund, Anna
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Trafikanttillstånd, TIL.
    Fors, Carina
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Trafikanttillstånd, TIL.
    Åkerstedt, Torbjörn
    Karolinska Institutet.
    Effects of the road environment on the development of driver sleepiness in young male drivers2018Inngår i: Accident Analysis and Prevention, ISSN 0001-4575, E-ISSN 1879-2057, Vol. 112, s. 127-134Artikkel i tidsskrift (Fagfellevurdert)
    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.
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Trafikanttillstånd, TIL.
    Anund, Anna
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Trafikanttillstånd, TIL.
    Fors, Carina
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Trafikanttillstånd, TIL.
    Åkerstedt, Torbjörn
    Stockholms Universitet.
    The effect of daylight versus darkness on driver sleepiness: A driving simulator study2017Inngår i: Journal of Sleep Research, ISSN 0962-1105, E-ISSN 1365-2869Artikkel i tidsskrift (Fagfellevurdert)
    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.
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Bolling, Anne
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Fordonsteknik och simulering, FTS.
    Sörensen, Gunilla
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Trafiksäkerhet, samhälle och trafikant, TST.
    Eriksson, Olle
    Statens väg- och transportforskningsinstitut, Infrastruktur, INFRA, Drift och underhåll, DOU.
    Andersson, Anders
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Fordonsteknik och simulering, FTS.
    Validating speed and road surface realism in VTI driving simulator III2012Rapport (Annet vitenskapelig)
    Abstract [sv]

    Nya simulatormodeller för vibrationer, ljud och grafik har utvecklats och implementerats i VTI:S fordonssimulator III. Syftet med denna studie är att validera simulatorn med avseende på hastighet och återgivandet av olika vägyteparametrar. Tjugofyra försökspersoner deltog i studien. De fick köra en och samma rutt i såväl simulator III som på verklig väg. Tre vägavsnitt med olika kvalitet på vägytan, från mycket slät till ganska ojämn, ingick i försöket. Såväl den objektiva förarparametern hastighet som olika subjektiva parametrar avseende förarens uppfattning om vägytans egenskaper (jämnhet, tysthet, komfort) jämfördes. Ett vägavsnitt med skiftande hastighetsgränser var av speciellt intresse. Ingen signifikant skillnad kunde noteras mellan körning i simulator och på verklig väg vare sig avseende hastighet (på avsitt med konstant hastighetsgräns) eller gradering av jämnhet och tysthet. För sträckan med skiftande hastighetsgränser fanns dock en signifikant skillnad mellan hastigheten i bil jämfört med hastigheten i simulator, trots liknande hastighetsprofiler. Såväl accelerationerna som retardationerna var snabbare i simulatorn. Vägkomforten graderades högre i bil än i simulator, men i båda fallen var tendensen den att slätare vägar gav högre värdering av komforten. Dessa resultat indikerar absolut validitet för graderingen av jämnhet och tysthet och för det objektiva måttet hastighet, medan relativ validitet indikerades för såväl hastighet vid skylt för hastighetsändring som för gradering av komfort.

  • 5.
    Ahlström, Christer
    et al.
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Dukic, Tania
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Comparison of eye tracking systems with one and three cameras2011Inngår i: ACM International Conference Proceeding Series, 2011Konferansepaper (Fagfellevurdert)
    Abstract [en]

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

  • 6.
    Ahlström, Christer
    et al.
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Dukic, Tania
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Ivarsson, Erik
    SmartEye.
    Kircher, Albert
    Statens väg- och transportforskningsinstitut.
    Rydbeck, Bosse
    SmartEye.
    Viström, Matias
    Saab Automobile.
    Performance of a one-camera and a three-camera system2010Rapport (Annet vitenskapelig)
    Abstract [en]

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

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

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

  • 7.
    Ahlström, Christer
    et al.
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Fors, Carina
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Anund, Anna
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Hallvig, David
    Stockholms Universitet.
    Video-based observer rated sleepiness versus self-reported subjective sleepiness in real road driving2015Inngår i: European Transport Research Review, ISSN 1867-0717, E-ISSN 1866-8887, Vol. 7, nr 4, artikkel-id 38Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

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

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

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

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

  • 8.
    Ahlström, Christer
    et al.
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Fors, Carina
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Forward, Sonja
    Statens väg- och transportforskningsinstitut, Samhälle, miljö och transporter, SAMT, Mobilitet, aktörer och planering, MAP.
    Gregersen, Nils Petter
    Statens väg- och transportforskningsinstitut, Samhälle, miljö och transporter, SAMT, Mobilitet, aktörer och planering, MAP.
    Hjälmdahl, Magnus
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Jansson, Jonas
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF.
    Kircher, Katja
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Lindberg, Gunnar
    Statens väg- och transportforskningsinstitut, Samhälle, miljö och transporter, SAMT, Transportekonomi Stockholm, TEK-S.
    Nilsson, Lena
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF.
    Patten, Christopher
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Dangerous use of mobile phones and other communication devices while driving: A toolbox of counter-measures2013Inngår i: Proceedings of the 16th International Conference Road Safety on Four Continents: Beijing, China. 15-17 May 2013, Linköping: Statens väg- och transportforskningsinstitut, 2013Konferansepaper (Annet vitenskapelig)
    Abstract [en]

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

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

  • 9.
    Ahlström, Christer
    et al.
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Trafikanttillstånd, TIL.
    Gink Lövgren, Maria
    Volvo Bus Corporation.
    Nilsson, Mats
    Volvo Bus Corporation.
    Dukic Willstrand, Tania
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Trafikanttillstånd, TIL.
    Anund, Anna
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Trafikanttillstånd, TIL.
    The effect of an active steering system on city bus drivers’ muscle activity2018Inngår i: International Journal of Occupational Safety and Ergonomics, ISSN 1080-3548, E-ISSN 2376-9130, s. 1-9Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    City bus drivers spend hours driving under time pressure, in congested traffic and in a monotonous sitting position. This leads to unhealthy working conditions, especially in terms of physical and psychological stress. The aim of this study is to investigate whether an active steering system can alleviate the musculoskeletal stress involved in manoeuvring a bus. Twenty bus drivers drove a city bus equipped with the Volvo dynamic steering (VDS) support system in real traffic. Steering effort was evaluated with electromyography and with a questionnaire. Compared to baseline, VDS significantly reduced the required muscle activity by on average 15–25% while turning, and up to 68% in the part of the manoeuvre requiring maximum effort. The bus drivers believed that VDS will help reduce neck and shoulder problems, and they expressed a desire to have VDS installed in their own bus.

  • 10.
    Ahlström, Christer
    et al.
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Trafikanttillstånd, TIL.
    Ihlström, Jonas
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Trafikanttillstånd, TIL.
    Kircher, Katja
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Trafikanttillstånd, TIL.
    Förares användning av kommunikationsutrustning under färd: Del 1: Enkätstudie. Del 2: Användning enligt objektiv mätning2017Rapport (Annet vitenskapelig)
    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.

  • 11.
    Ahlström, Christer
    et al.
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Trafikanttillstånd, TIL.
    Jansson, Sabina
    Linköpings Universitet.
    Anund, Anna
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Trafikanttillstånd, TIL.
    Local changes in the wake electroencephalogram precedes lane departures2017Inngår i: Journal of Sleep Research, ISSN 0962-1105, E-ISSN 1365-2869Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 12.
    Ahlström, Christer
    et al.
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Trafikanttillstånd, TIL.
    Kircher, Katja
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Trafikanttillstånd, TIL. Linköpings Universitet.
    A Generalized Method to Extract Visual Time-Sharing Sequences From Naturalistic Driving Data2017Inngår i: IEEE transactions on intelligent transportation systems (Print), ISSN 1524-9050, E-ISSN 1558-0016, Vol. 18, nr 11, s. 2929-2938Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 13.
    Ahlström, Christer
    et al.
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Trafikanttillstånd, TIL.
    Kircher, Katja
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Trafikanttillstånd, TIL. Linköping University.
    Changes in glance behaviour when using a visual eco-driving system: A field study2017Inngår i: Applied Ergonomics, ISSN 0003-6870, E-ISSN 1872-9126, Vol. 58, s. 414-423Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 14.
    Ahlström, Christer
    et al.
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Kircher, Katja
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Review of real-time visual driver distraction detection algorithms2011Inngår i: ACM International Conference Proceeding Series, 2011Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Many incidents and crashes can be attributed to driver distraction, and it is essential to learn how to detectdistraction in order to develop efficient countermeasures. A number of distraction detection algorithms have been developed over the years, and the objective of this paper is to summarize available approaches and to describe these algorithms in a unified framework. The review is limited to real-time algorithms that are intended to detect visual distraction.

  • 15.
    Ahlström, Christer
    et al.
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Kircher, Katja
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Fors, Carina
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Dukic, Tania
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Patten, Christopher
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Anund, Anna
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Measuring driver impairments: Sleepiness, distraction, and workload2012Inngår i: IEEE Pulse, ISSN 2154-2287, Vol. 3, nr 2, s. 22-30Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Snow was falling heavily when Sarah was driving on a slippery road to her cousin’s country cottage. It was dark outside, and the visibility was poor. She had planned to arrive before sunset, but the rental service had made a mistake, and it took hours before she got her rental car at the airport. It was past midnight now, and after a long day of traveling, Sarah was starting to get sleepy.

    Fortunately, there were only 15 km to go, but her eyelids were starting to feel heavy. To stay awake, she put her favorite CD on, turned up the volume, and started to sing along. This seemed to help a little -good- only 10 km to go. This was when Sarah’s phone started ringing, and she awkwardly tried to find the mute button for the car stereo while answering the phone. As she looked up again, she barely caught a glimpse of the red brake lights of the car in front of her as she smashed into it.

  • 16.
    Ahlström, Christer
    et al.
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Kircher, Katja
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Kircher, Albert
    Linköpings Universitet.
    A gaze-based driver distraction warning system and its effect on visual behaviour2013Inngår i: IEEE transactions on intelligent transportation systems (Print), ISSN 1524-9050, E-ISSN 1558-0016, Vol. 14, nr 2, s. 965-973Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Driver distraction is a contributing factor to many crashes; therefore, a real-time distraction warning system should have the potential to mitigate or circumvent many of these crashes. The objective of this paper is to investigate the usefulness of a real-time distraction detection algorithm called AttenD. The evaluation is based on data from an extended field study comprising seven drivers who drove on an average of 4351 ± 2181 km in a naturalistic setting.

    Visual behavior was investigated both on a global scale and on a local scale in the surroundings of each warning. An increase in the percentage of glances at the rear-view mirror and a decrease in the amount of glances at the center console were found. The results also show that visual time sharing decreased in duration from 9.94 to 9.20 s due to the warnings, that the time from fully attentive to warning decreased from 3.20 to 3.03 s, and that the time from warning to full attentiveness decreased from 6.02 to 5.46 s. The limited number of participants does not allow any generalizable conclusions, but a trend toward improved visual behavior could be observed. This is a promising start for further improvements of the algorithm and the warning strategy.

  • 17.
    Ahlström, Christer
    et al.
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Kircher, Katja
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Kircher, Albert
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Fordonsteknik och simulering, FTS.
    Considerations when calculating percent road centre from eye movement data in driver distraction monitoring2009Inngår i: Proceedings of the Fifth International Driving Symposium on Human Factors in Driver Assessment, Training and Vehicle Design, 2009, s. 132-139Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Percent road center (PRC) is a performance indicator which is sensitive to driver distraction. The original definition of PRC is based on fixation data extracted from eye movement recordings, but it has also been suggested that PRC can be determined directly from the gaze data without segmenting it into saccades and fixations. The primary aim of this paper is to investigate if this is the case.

    Naturalistic driving data from a small scale field operational test comprising seven vehicles was used in the evaluation. It was found that PRC time traces based on gaze data and fixation data, respectively, were highly similar (correlation coefficient=0.95, average wavelet semblance=0.84) except for an absolute amplitude difference of about 8%. This indicates that the two approaches can be used interchangeably and that the processing step of segmenting gaze data into saccades and fixations can be left out.

    In addition to this finding, design issues related to the calculation of PRC are investigated. Especially, the impact of gaze cases pointing towards the intersection of the road centre area and the centre rear mirror were investigated. Results lead to conclude that gazes and fixations on the centre rear mirror should be removed from the PRC calculations, as they may negatively influence the correctness of the performance indicator.

  • 18.
    Ahlström, Christer
    et al.
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Kircher, Katja
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Rydström, Annie
    Volvo Car Corperation.
    Nåbo, Arne
    SAAB Automobile.
    Almgren, Susanne
    SAAB Automobile.
    Ricknäs, Daniel
    Scania.
    Effects of visual, cognitive and haptic tasks on driving performance indicators2012Inngår i: Advances in Human Aspects of Road and Rail Transportation / [ed] Neville A . Stanton, San Francisco, USA: CRC Press , 2012, s. 673-682Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A driving simulator study was conducted by using the same setup in two driving simulators, one with a moving base and one with a fixed base. The aim of the study was to investigate a selection of commonly used performance indicators (PIs) for their sensitivity to secondary tasks loading on different modalities and levels of difficulty, and to evaluate their robustness across simulator platforms. The results showed that, across platforms, the longitudinal PIs behaved similarly whereas the lateral control and eye movement based performance indicators differed. For modality, there were considerable effects on lateral, longitudinal as well as eye movement PIs. However, there were only limited differences between the baseline and the cognitive and haptic tasks. For difficulty, clear effects on PIs related to lateral control and eye movements were shown. Additionally, it should be noted that there were large individual differences for several of the PIs. In conclusion, many of the most commonly used PIs are susceptible to individual differences, and, especially the PIs for lateral control, to the platform and environment where they are acquired, which is why generalizations should be made with caution.

  • 19.
    Ahlström, Christer
    et al.
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Kircher, Katja
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Thorslund, Birgitta
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Adell, Emeli
    Trivector Traffic.
    Bicyclists’ visual strategies when conducting self-paced vs. system-paced smartphone tasks in traffic2015Inngår i: Transportation Research Part F: Traffic Psychology and Behaviour, ISSN 1369-8478, E-ISSN 1873-5517, Vol. 41, s. 204-216Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

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

  • 20.
    Ahlström, Christer
    et al.
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Nyström, Marcus
    Lunds Universitet.
    Holmqvist, Kenneth
    Lunds Universitet.
    Fors, Carina
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Sandberg, David
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Anund, Anna
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Kecklund, Göran
    Stockholms Universitet.
    Ņkerstedt, Torbjörn
    Stockholms Universitet.
    Fit-for-duty test for estimation of drivers’ sleepiness level: Eye movements improve the sleep/wake predictor2013Inngår i: Transportation Research Part C: Emerging Technologies, ISSN 0968-090X, E-ISSN 1879-2359, Vol. 26, s. 20-32Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Driver sleepiness contributes to a considerable proportion of road accidents, and a fit-for-duty test able to measure a driver’s sleepiness level might improve traffic safety. The aim of this study was to develop a fit-for-duty test based on eye movement measurements and on the sleep/wake predictor model (SWP, which predicts the sleepiness level) and evaluate the ability to predict severe sleepiness during real road driving. Twenty-four drivers participated in an experimental study which took place partly in the laboratory, where the fit-for-duty data were acquired, and partly on the road, where the drivers sleepiness was assessed. A series of four measurements were conducted over a 24-h period during different stages of sleepiness. Two separate analyses were performed; a variance analysis and a feature selection followed by classification analysis. In the first analysis it was found that the SWP and several eye movement features involving anti-saccades, pro-saccades, smooth pursuit, pupillometry and fixation stability varied significantly with different stages of sleep deprivation. In the second analysis, a feature set was determined based on floating forward selection. The correlation coefficient between a linear combination of the acquired features and subjective sleepiness (Karolinska sleepiness scale, KSS) was found to be R=. 0.73 and the correct classification rate of drivers who reached high levels of sleepiness (KSS ≥ 8) in the subsequent driving session was 82.4% (sensitivity = 80.0%, specificity = 84.2% and AUC = 0.86). Future improvements of a fit-for-duty test should focus on how to account for individual differences and situational/contextual factors in the test, and whether it is possible to maintain high sensitive/specificity with a shorter test that can be used in a real-life environment, e.g. on professional drivers. © 2012 Elsevier Ltd.

  • 21.
    Ahlström, Christer
    et al.
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Victor, Trent
    Chalmers University of Technology.
    Wege, Claudia
    Steinmetz, Erik
    SP Technical Research Institute Sweden.
    Processing of eye/head-tracking data in large-scale naturalistic driving data sets2012Inngår i: IEEE transactions on intelligent transportation systems (Print), ISSN 1524-9050, E-ISSN 1558-0016, Vol. 13, nr 2, s. 553-564Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Driver distraction and driver inattention are frequently recognized as leading causes of crashes and incidents. Despite this fact, there are few methods available for the automatic detection of driver distraction. Eye tracking has come forward as the most promising detection technology, but the technique suffers from quality issues when used in the field over an extended period of time. Eye-tracking data acquired in the field clearly differs from what is acquired in a laboratory setting or a driving simulator, and algorithms that have been developed in these settings are often unable to operate on noisy field data. The aim of this paper is to develop algorithms for quality handling and signal enhancement of naturalistic eye- and head-tracking data within the setting of visual driver distraction. In particular, practical issues are highlighted. Developed algorithms are evaluated on large-scale field operational test data acquired in the Sweden-Michigan Field Operational Test (SeMiFOT) project, including data from 44 unique drivers and more than 10000 trips from 13 eye-tracker-equipped vehicles. Results indicate that, by applying advanced data-processing methods, sensitivity and specificity of eyes-off-road glance detection can be increased by about 10%. In conclusion, postenhancement and quality handling is critical when analyzing large databases with naturalistic eye-tracking data. The presented algorithms provide the first holistic approach to accomplish this task. © 2011 IEEE.

  • 22.
    Ahlström, Christer
    et al.
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Trafikanttillstånd, TIL.
    Wachtmeister, Jesper
    Mobile Behaviour.
    Nyman, Mattias
    Designingenjörerna Sverige AB.
    Nordenström, Axel
    Designingenjörerna Sverige AB.
    Kircher, Katja
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Trafikanttillstånd, TIL.
    Using smartphone logging to gain insight about phone use in traffic2019Inngår i: Cognition, Technology & Work, ISSN 1435-5558, E-ISSN 1435-5566Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The prevalence of mobile phone usage in traffic has been studied by road-side counting, naturalistic driving data, surveillance cameras, smartphone logging, and subjective estimates via surveys. Here, we describe a custom-made smartphone logging application along with suggestions on how future such applications should be designed. The developed application logs’ start and end times of all phone interactions (mobile phone applications, incoming/outgoing phone calls and text messages, audio output, and screen activations). In addition, all movements are automatically classified into transport, cycling, walking, running, or stationary. The capabilities of the approach are demonstrated in a pilot study with 143 participants. Examples of results that can be gained from smartphone logging include prevalence in different transportation modes (here found to be 12% while driving, 4% while cycling, and 7% while walking), which apps are being used (here found to be 19% navigation, 12% talking, 12% social media, and 10% games) and on which road types (rural, urban, highway etc.). Smartphone logging was found to be an insightful complement to the other methods for assessing phone use in traffic, especially since it allows the analyses of which apps are used and where they are used, split into transportation mode and road type, all at a relatively low cost.

  • 23.
    Antonson, Hans
    et al.
    Statens väg- och transportforskningsinstitut, Samhälle, miljö och transporter, SAMT, Mobilitet, aktörer och planering, MAP.
    Ahlström, Christer
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Mårdh, Selina
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Blomqvist, Göran
    Statens väg- och transportforskningsinstitut, Samhälle, miljö och transporter, SAMT, Miljö, MILJÖ.
    Wiklund, Mats
    Trafikanalys .
    Landscape heritage objects' effect on driving: a combined driving simulator and questionnaire study.2014Inngår i: Accident Analysis and Prevention, ISSN 0001-4575, E-ISSN 1879-2057, Vol. 62, s. 168-77Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    According to the literature, landscape (panoramas, heritage objects e.g. landmarks) affects people in various ways. Data are primarily developed by asking people (interviews, photo sessions, focus groups) about their preferences, but to a lesser degree by measuring how the body reacts to such objects. Personal experience while driving a car through a landscape is even more rare.

    In this paper we study how different types of objects in the landscape affect drivers during their drive. A high-fidelity moving-base driving simulator was used to measure choice of speed and lateral position in combination with stress (heart rate measure) and eye tracking. The data were supplemented with questionnaires. Eighteen test drivers (8 men and 10 women) with a mean age of 37 were recruited. The test drivers were exposed to different new and old types of landscape objects such as 19th century church, wind turbine, 17th century milestone and bus stop, placed at different distances from the road driven.

    The findings are in some respect contradictory, but it was concluded that that 33% of the test drivers felt stressed during the drive. All test drivers said that they had felt calm at times during the drive but the reason for this was only to a minor degree connected with old and modern objects. The open landscape was experienced as conducive to acceleration. No significant differences could be observed concerning the test drivers' gaze between old or modern objects, but a significant difference was observed between the test drivers' gaze between road stretches with faraway objects and stretches without objects.

  • 24.
    Antonson, Hans
    et al.
    Statens väg- och transportforskningsinstitut, Samhälle, miljö och transporter, SAMT, Mobilitet, aktörer och planering, MAP.
    Ahlström, Christer
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Wiklund, Mats
    Statens väg- och transportforskningsinstitut, Infrastruktur, INFRA, Drift och underhåll, DOU.
    Blomqvist, Göran
    Statens väg- och transportforskningsinstitut, Samhälle, miljö och transporter, SAMT, Miljö, MILJÖ.
    Mårdh, Selina
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Crash Barriers and Driver Behavior: A Simulator Study2013Inngår i: Traffic Injury Prevention, ISSN 1538-9588, E-ISSN 1538-957X, Vol. 14, nr 8, s. 874-880Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Objective: The study examines how drivers experience a conventional W-beam guardrail (metal crash barrier) along both sides of narrow versus wider roads (single carriageway with 2 lanes) in terms of stress, feelings, and driving patterns and whether subjective experience concurs with the actual driving patterns captured by the quantitative data.

    Methods: The study used different methods to capture data, including the VTI Driving Simulator III (speed and lateral vehicle position) in conjunction with electrocardiogram (ECG) data on heart rate variability (HRV) and questionnaires (oral during driving and written after driving). Eighteen participants-8 men and 10 women-were recruited for the simulator study and the simulator road section was 10 km long.

    Results: Driving speeds increased slightly on the wider road and on the road with a crash barrier, and the lateral driving position was nearer to the road center on the narrower road and on the road with a crash barrier. The HRV data did not indicate that participants experienced greater stress due to road width or due to the presence of a crash barrier. Participant experience captured in the oral questionnaires suggested that road width did not affect driver stress or driving patterns; however, the written questionnaire results supported the simulator data, indicating that a wider road led to increased speed. None of the participants felt that crash barriers made them feel calmer.

    Conclusions: We believe that there is a possibility that the increased speed on roads with crash barriers may be explained by drivers’ sense of increased security. This study demonstrates that an experimental design including experience-based data captured using both a simulator and questionnaires is productive. It also demonstrates that driving simulators can be used to study road features such as crash barriers. It seems more than likely that features such as street lamps, signs, and landscape objects could be tested in this way. © 2013 Copyright Taylor and Francis Group, LLC.

  • 25.
    Antonson, Hans
    et al.
    Statens väg- och transportforskningsinstitut, Samhälle, miljö och transporter, SAMT, Mobilitet, aktörer och planering, MAP.
    Jägerbrand, Annika K
    Statens väg- och transportforskningsinstitut, Samhälle, miljö och transporter, SAMT, Miljö, MILJÖ.
    Ahlström, Christer
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Experiencing moose and landscape while driving: a simulator and questionnaire study2014Inngår i: Journal of Environmental Psychology, ISSN 0272-4944, E-ISSN 1522-9610, Vol. 41, s. 91-100Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Animal vehicle collisions (AVC's) have large economic, medical and ecological consequences but have rarely been studied with respect to driver behaviour. The aim of this study was to investigate different AVC-relevant landscape settings (vegetation cover), with and without game fencing and in combination with encountering moose. Twenty-five participants took part in an advanced driving simulator experiment. The results show that neither the presence of a game fence nor vegetation was found to affect driving speed, speed variability, lateral position or visual scanning in general. When a moose appeared at the side of the road, the drivers reacted by slowing down earlier and reducing their speed more when no game fence was present. Furthermore, the speed reduction when a moose was present was significantly larger when the vegetation was sparse. Game fencing made drivers feel at ease whereas dense vegetation was experienced as more stressful.

  • 26.
    Antonson, Hans
    et al.
    Statens väg- och transportforskningsinstitut, Mobilitet, aktörer och planering, MAP.
    Jägerbrand, Annika K.
    Statens väg- och transportforskningsinstitut, Miljö, MILJÖ.
    Ahlström, Christer
    Statens väg- och transportforskningsinstitut, Samspel människa, fordon, transportsystem, MFT.
    Experiencing moose and landscape while driving: a simulator and questionnaire study2014Inngår i: Journal of Environmental Psychology, ISSN 0272-4944, E-ISSN 1522-9610, Vol. 41, s. 91-100Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Animal vehicle collisions (AVC's) have large economic, medical and ecological consequences but have rarely been studied with respect to driver behaviour. The aim of this study was to investigate different AVC-relevant landscape settings (vegetation cover), with and without game fencing and in combination with encountering moose. Twenty-five participants took part in an advanced driving simulator experiment. The results show that neither the presence of a game fence nor vegetation was found to affect driving speed, speed variability, lateral position or visual scanning in general. When a moose appeared at the side of the road, the drivers reacted by slowing down earlier and reducing their speed more when no game fence was present. Furthermore, the speed reduction when a moose was present was significantly larger when the vegetation was sparse. Game fencing made drivers feel at ease whereas dense vegetation was experienced as more stressful.

  • 27.
    Anund, Anna
    et al.
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Ahlström, Christer
    Statens väg- och transportforskningsinstitut.
    Almqvist, Sverker
    Statens väg- och transportforskningsinstitut.
    Yahya, Mohammad-Reza
    Statens väg- och transportforskningsinstitut.
    Småskalig ITS: utvärdering av effekten av lokala VMS-system i tätort2009Rapport (Annet vitenskapelig)
    Abstract [sv]

    This study investigates the acceptance and effect of variable message signs (VMS). Two different systems were evaluated: one where a speed limit sign was combined with a message to slow down and another where a speed limit sign was combined with flashing lights. Both VMS were activated (lit up) if the passing vehicle was driving too fast as it approached the speed limit sign. The aim of the study was to evaluate if the use of a variable speed limit sign gave rise to lower speeds. The same approach was used in order to evaluate the effect of an additional message system or flashing lights. The investigation was conducted in two Swedish villages, Grästorp and Färgelanda, at road sections where the speed limit was momentarily reduced to 50 km/h. In both locations, the use of a variable speed limit sign resulted in speed reduction (mean and 85 percentiles) amongst the drivers. This means that the majority of the drivers, including those that drove much too fast, reduced their speed owing to the VMS. However, no further speed reductions were found when combining the variable speed limit signs with either a message system or flashing lights. Interviews with the drivers revealed that they believed that both VMS systems would increase traffic safety by reducing the speeds. They also stated that variable speed limit sign was enough to increase their awareness of the current speed limit and that no additional message systems or the blinking lights were necessary.

  • 28.
    Anund, Anna
    et al.
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Trafikanttillstånd, TIL.
    Ahlström, Christer
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Trafikanttillstånd, TIL.
    Fors, Carina
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Trafikanttillstånd, TIL.
    Åkerstedt, Torbjörn
    Karolinska Institutet.
    Are professional drivers less sleepy than non-professional drivers?2018Inngår i: Scandinavian Journal of Work, Environment and Health, ISSN 0355-3140, E-ISSN 1795-990X, Vol. 44, nr 1, s. 88-95Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 29.
    Anund, Anna
    et al.
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Ahlström, Christer
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Forsberg, Inger
    Statens väg- och transportforskningsinstitut, Samhälle, miljö och transporter, SAMT, Mobilitet, aktörer och planering, MAP.
    Nyberg, Jonna
    Statens väg- och transportforskningsinstitut, Samhälle, miljö och transporter, SAMT, Mobilitet, aktörer och planering, MAP.
    Räfflor i mitten av körfältet: ett försök i Skaulo2010Rapport (Annet vitenskapelig)
    Abstract [en]

    The aim with the study was to evaluate the effects on road user behavior when using milled rumble strips in the centre of the lane on a road 6.5 meters wide. The evaluation included measurements of speed and lateral position. Measurements were done before and after milling, and focus group interviews were perfomed with motorcyclists and truck drivers after realisation. The results of the measurements of speed and lateral position showed that milled rumble strips in the middle of the lane do not affect car drivers. A slight increase in the standard deviation of the lateral position for passenger cars may be noted. Truck drivers were affected slightly more: significantly lower speed was detected as well as that trucks moved closer to the road centre, and the standard deviation of lateral position increased. This is not what the drivers themselves report to experience. They say that their choice of speed is unchanged. All in all truck drivers were negative to the rumble strips in the centre of the lane. One argument was that they disturbe the "line" during the drive and make it difficult to choose the placement they want to have. Truck drivers do not believe that they, in case of falling asleep, (in contrary to expectations) would have time enough to act in order to aviod a crash, since the roads are too narrow. Also the motorcyclists are negative to the centre lane location of rumble strips. They agree, however, that rumble strips in the centre of the road and in the roadside are postitive in terms of traffic safety.

  • 30.
    Anund, Anna
    et al.
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Ahlström, Christer
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Kecklund, Göran
    Stress Research Institute, Stockholm University.
    Ņkerstedt, Torbjörn Bjorn
    Stress Research Institute, Stockholm University.
    Rumble strips in centre of the lane and the effect on sleepy drivers2011Inngår i: Industrial Health, ISSN 0019-8366, E-ISSN 1880-8026, Vol. 49, nr 5, s. 549-558Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The aim of this study was to describe the effects of sleep loss on behavioural and subjective indicators of sleepiness on a road containing a milled rumble strip in the centre of the lane. Particular attention was paid to behavioural and subjective indicators of sleepiness when using the centre lane rumble strip, and to possible erratic driving behaviour when hitting a rumble strip. In total 9 regular shift workers drove during the morning hours after a full night shift and after a full night sleep. The order was balanced. The experiment was conducted in a moving base driving simulator on rural roads with a road width of 6.5 and 9 meters. Out of the 1,636 rumble strip hits that occurred during the study, no indications of erratic driving behaviour associated with the jolt caused by making contact with the centre lane rumble strip could be found. Comparing the alert condition with the sleep deprived condition, both the standard deviation of lateral position (SDLP) and the Karolinska Sleepiness Scale (KSS) increased for sleepy drivers. For the two road widths, the drivers drove closer to the centre line on the 6.5-meter road. The KSS and the SDLP increased with time on task. This simulator study indicates that rumble strips in the centre of the lane may be an alternative to centreline and edgeline rumble strips on narrow roads.

  • 31.
    Anund, Anna
    et al.
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Trafikanttillstånd, TIL. Linköpings Universitet.
    Fors, Carina
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Trafikanttillstånd, TIL.
    Ahlström, Christer
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Trafikanttillstånd, TIL.
    The severity of driver fatigue in terms of line crossing: a pilot study comparing day- and night time driving in simulator2017Inngår i: European Transport Research Review, ISSN 1867-0717, E-ISSN 1866-8887, Vol. 9, nr 2, artikkel-id 31Artikkel i tidsskrift (Fagfellevurdert)
    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).

  • 32.
    Axelson, M.
    et al.
    Linköpings universitet.
    Ahlström, Christer
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Trafikanttillstånd, TIL.
    Krupenia, S.
    Scania.
    Anund, Anna
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Trafikanttillstånd, TIL.
    Leeuwen, W.
    Stockholms Universitet.
    Kecklund, G.
    Stockholms Universitet.
    Is it possible to adjust the driving and resting times when operating highly autonomous trucks?2018Inngår i: Journal of Sleep Research, ISSN 0962-1105, E-ISSN 1365-2869, Vol. 27, nr Suppl. 1, artikkel-id P345Artikkel i tidsskrift (Annet vitenskapelig)
  • 33.
    Barua, Shaibal
    et al.
    Mälardalens Högskola.
    Ahmed, Mobyen Uddin
    Mälardalens Högskola.
    Ahlström, Christer
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Trafikanttillstånd, TIL.
    Begum, Shahina
    Mälardalens Högskola.
    Automatic driver sleepiness detection using EEG, EOG and contextual information2019Inngår i: Expert systems with applications, ISSN 0957-4174, E-ISSN 1873-6793, Vol. 115, s. 121-135Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 34.
    Barua, Shaibal
    et al.
    Mälardalens högskola.
    Ahmed, Mobyen Uddin
    Ahlström, Christer
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Trafikanttillstånd, TIL.
    Begum, Shahina
    Mälardalens högskola.
    Funk, Peter
    Mälardalens högskola.
    Automated EEG Artifact Handling with Application in Driver Monitoring2017Inngår i: IEEE journal of biomedical and health informatics, ISSN 2168-2194, E-ISSN 2168-2208Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 35.
    Dukic, Tania
    et al.
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Ahlström, Christer
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Björketun, Urban
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Trafiksäkerhet, samhälle och trafikant, TST.
    Kettwich, Carmen
    Karlsruhe Institute of Technology.
    Yahya, Mohammad Reza
    Statens väg- och transportforskningsinstitut, Samhälle, miljö och transporter, SAMT, Trafikanalys och logistik, TAL.
    Patten, Christopher
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Tapani, Andreas
    Statens väg- och transportforskningsinstitut, Samhälle, miljö och transporter, SAMT, Trafikanalys och logistik, TAL.
    Vadeby, Anna
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Trafiksäkerhet, samhälle och trafikant, TST.
    Inverkan av elektroniska reklamskyltar på trafiksäkerhet: en studie på E4 i Stockholm2011Rapport (Annet vitenskapelig)
    Abstract [sv]

    Denna rapport presenterar fyra delstudier som genomfördes med syftet att utvärdera hur elektroniskareklamskyltar (ERS) påverkar trafiksäkerheten.Delstudie 1 är en litteraturstudie som undersökte påverkan av ERS på trafiksäkerhet. Slutsatsen var attrörliga bilder samt placering av skyltarna har en stor inverkan på förarens beteende och att i mörker och iogynnsamma väderförhållanden kan ljusbilden upplevas som bländande vilket försvårar körningenspeciellt för äldre förare.Den andra och tredje delstudien jämförde trafiken före och efter installation av ERS. En jämförelse avhastighet och olyckor gjordes. Inga skillnader i trafikflöde och medelhastighet som beror på ERS kundepåvisas. Sammantaget fanns inget i det studerade olycksmaterialet som tyder på att olycksutfalletpåverkats av ERS.Den fjärde delstudien är en fältstudie som undersöker förares beteende i verklig miljö när de passerarERS på motorvägen. Mätningar av visuellt beteende samt körbeteende visar flera fall av visuell distraktionvid passage av ERS. Effekter på kördata kunde inte påvisas. Resultaten visar också en negativinställning till ERS för en majoritet av förarna.Sammanfattningsvis kan ingen påverkan från ERS på trafiksäkerhet ses på makronivå. Dock måsteeffekterna på visuell distraktion tas i beaktning och undersökas närmare innan det beslutas huruvida ERSblir en verklighet på svenska vägar.

  • 36.
    Dukic, Tania
    et al.
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Ahlström, Christer
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Patten, Christopher
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Kettwich, Carmen
    Karlsruhe Institute of Technology.
    Kircher, Katja
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Effects of electronic billboards on driver distraction.2013Inngår i: Traffic Injury Prevention, ISSN 1538-9588, E-ISSN 1538-957X, Vol. 14, nr 5, s. 469-76Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    OBJECTIVE: There is an increase in electronic advertising billboards along major roads, which may cause driver distraction due to the highly conspicuous design of the electronic billboards. Yet limited research on the impact of electronic billboards on driving performance and driver behavior is available. The Swedish Transport Administration recently approved the installation of 12 electronic billboards for a trial period along a 3-lane motorway with heavy traffic running through central Stockholm, Sweden. The aim of this study was to evaluate the effect of these electronic billboards on visual behavior and driving performance.

    METHOD: A total of 41 drivers were recruited to drive an instrumented vehicle passing 4 of the electronic billboards during day and night conditions. A driver was considered visually distracted when looking at a billboard continuously for more than 2 s or if the driver looked away from the road for a high percentage of time. Dependent variables were eye-tracking measures and driving performance measures.

    RESULTS: The visual behavior data showed that drivers had a significantly longer dwell time, a greater number of fixations, and longer maximum fixation duration when driving past an electronic billboard compared to other signs on the same road stretches. No differences were found for the factors day/night, and no effect was found for the driving behavior data.

    CONCLUSION: Electronic billboards have an effect on gaze behavior by attracting more and longer glances than regular traffic signs. Whether the electronic billboards attract too much attention and constitute a traffic safety hazard cannot be answered conclusively based on the present data.

  • 37.
    Eriksson, Lars
    et al.
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Bolling, Anne
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Fordonsteknik och simulering, FTS.
    Alm, Torbjörn
    HiQ.
    Andersson, Anders
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Fordonsteknik och simulering, FTS.
    Ahlström, Christer
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Blissing, Björn
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Fordonsteknik och simulering, FTS.
    Nilsson, Göran
    Svenska vägmarkeringsföreningen, SVMF.
    Driver acceptance and performance with LDW and rumble strips assistance in unintentional lane departures2013Rapport (Annet vitenskapelig)
    Abstract [en]

    In this ViP project the focus of investigation was whether drivers more readily accept either rumble strips or an in-vehicle lane departure warning system (LDW) in unintentional lane departure situations. The results show that acceptance was high for both alternatives, but while the drivers showed more satisfaction from using the LDW, they also showed more trust in the rumble strips. Twenty-four drivers drove the VTI driving simulator SIM III in car mode with simulated rumble strips in one drive and with a simulated Volvo LDW in another drive. A forced yaw motion of the vehicle induced the unintentional lane departures. The results showed no choice in favour of the LDW or the rumble strips, but a clear preference for having a function that warns for unintentional lane departure. Several participants thought it was good to have both types of warning in parallel. Although Response completion time was shorter with the rumble strips warning, there was no difference between the warning types, neither in Time to get car back in lane nor in Lane exceedence area. Thus, there were no major overall differences between the LDW and the rumble strips as measured in the present study. The conclusion is that the drivers’ acceptance, as well as performance, was high for both the rumble strips and the LDW. The positive opinion on the need for assistance systems in unintentional lane departure when drivers are directing their visual attention away from the road is thus further strengthened.

  • 38.
    Filtness, Ashleigh J
    et al.
    Queensland University of Technology.
    Anund, Anna
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Fors, Carina
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Ahlström, Christer
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Åkerstedt, Torbjörn
    Stockholms Universitet.
    Kecklund, Göran
    Stockholms Universitet.
    Sleep-related eye symptoms and their potential for identifying driver sleepiness2014Inngår i: Journal of Sleep Research, ISSN 0962-1105, E-ISSN 1365-2869, Vol. 23, nr 5, s. 568-75Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The majority of individuals appear to have insight into their own sleepiness, but there is some evidence that this does not hold true for all, for example treated patients with obstructive sleep apnea. Identification of sleep-related symptoms may help drivers determine their sleepiness, eye symptoms in particular show promise. Sixteen participants completed four motorway drives on two separate occasions. Drives were completed during daytime and night-time in both a driving simulator and on the real road.

    Ten eye symptoms were rated at the end of each drive, and compared with driving performance and subjective and objective sleep metrics recorded during driving. 'Eye strain', 'difficulty focusing', 'heavy eyelids' and 'difficulty keeping the eyes open' were identified as the four key sleep-related eye symptoms. Drives resulting in these eye symptoms were more likely to have high subjective sleepiness and more line crossings than drives where similar eye discomfort was not reported. Furthermore, drivers having unintentional line crossings were likely to have 'heavy eyelids' and 'difficulty keeping the eyes open'. Results suggest that drivers struggling to identify sleepiness could be assisted with the advice 'stop driving if you feel sleepy and/or have heavy eyelids or difficulty keeping your eyes open'.

  • 39.
    Fors, Carina
    et al.
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Trafikanttillstånd, TIL.
    Ahlström, Christer
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Trafikanttillstånd, TIL.
    Anund, Anna
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Trafikanttillstånd, TIL.
    A comparison of driver sleepiness in the simulator and on the real road2016Inngår i: Journal of Transportation Safety and Security, ISSN 1943-9962, s. 1-16Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 40.
    Fors, Carina
    et al.
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Ahlström, Christer
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Anund, Anna
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Simulator validation with respect to driver sleepiness and subjective experiences: final report of the project SleepEYE II, part 12013Rapport (Annet vitenskapelig)
    Abstract [en]

    In the previous project SleepEYE, which aimed at developing tools for driver sleepiness detection, two experiments were carried out. In the first experiment, 18 drivers conducted two driving sessions on a motorway: one during daytime (alert) and one at night (sleep deprived). Sixteen of the drivers participated in the second experiment, which was similar to the first one, except that the driving sessions were conducted in an advanced moving base driving simulator. In the present study, the validity of the simulator was assessed using data that was collected in the two experiments. The validation analysis had three focuses: 1) general driver and driving behaviour related to driver sleepiness, 2) speed profile at change in posted speed limit, and 3) drivers’ subjective experience of the vehicle, the driving environment and the own driving performance. The results showed that there were significant differences in mean speed, blink duration, percentage road centre (gaze), radius of 95 per cent cone (gaze) and KSS between the simulator and the real road. No such differences were found for left and right line crossings. For all indicators except blink duration, there was no interaction effect between platform (simulator vs. real road) and time on task, which indicates that the signs of sleepiness vary in a similar way regardless of platform. In conclusion, differences between the simulator and the real road with respect to driving and driver behaviour as well as subjective experiences were found, mainly in terms of speed, level of sleepiness and subjective experience of the vehicle. However, the signs of sleepiness and the development of sleepiness over time are similar in the simulator and on the real road, although the level is higher in the simulator. Thus, there is a relative but not absolute validity with respect to driver sleepiness. Similarly, there seems to be a relative validity for speed and changes in speed.

  • 41.
    Fors, Carina
    et al.
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Ahlström, Christer
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Sörner, Per
    Smart eye.
    Kovaceva, Jordanka
    Volvo cars.
    Hasselberg, Emanuel
    Smart eye.
    Krantz, Martin
    Smart eye.
    Grönvall, John-Fredrik
    Volvo cars.
    Kircher, Katja
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Anund, Anna
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Camera-based sleepiness detection: final report of the project SleepEYE2011Rapport (Annet vitenskapelig)
    Abstract [en]

    Two literature reviews were conducted in order to identify indicators of driver sleepiness and distraction. Three sleepiness indicators – blink duration, blink frequency and Perclos – were implemented in the camera system.

    The aims of the study were firstly to develop and evaluate a low cost 1-camera unit for detection of driver impairment, and secondly to identify indicators of driver sleepiness and to create a sleepiness classifier for driving simulators.

    The project included two experiments. The first was a field test where 18 participants conducted one alert and one sleepy driving session on a motorway. 16 of the 18 participants also participated in the second experiment which was a simulator study similar to the field test.

    The field test data was used for evaluation of the 1-camera system, with respect to the sleepiness indicators. Blink parameters from the 1-camera system was compared to blink parameters obtained from a reference 3-camera system and from the EOG. It was found that the 1-camera system missed many blinks and that the blink duration was not in agreement with the blink duration obtained from the EOG and from the reference 3-camera system. However, the results also indicated that it should be possible to improve the blink detection algorithm since the raw data looked well in many cases where the algorithm failed to identify blinks.

    The sleepiness classifier was created using data from the simulator experiment. In the first step, the indicators identified in the literature review were implemented and evaluated. The indicators also included driving and context related parameters in addition to the blink related ones. The most promising indicators were then used as inputs to the classifier.

  • 42.
    Fors, Carina
    et al.
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Kircher, Katja
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Ahlström, Christer
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Interface design of eco-driving support systems: Truck drivers’ preferences and behavioural compliance2015Inngår i: Transportation Research Part C: Emerging Technologies, ISSN 0968-090X, E-ISSN 1879-2359, Vol. 58, s. 706-720Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The aim of the study was to investigate the perceived usefulness of various types of in-vehicle feedback and advice on fuel efficient driving. Twenty-four professional truck drivers participated in a driving simulator study. Two eco-driving support systems were included in the experiment: one that provided continuous information and one that provided intermittent information. After the simulator session, the participants were interviewed about their experiences of the various constituents of the systems. In general, the participants had a positive attitude towards eco-driving support systems and behavioural data indicated that they tended to comply with the advice given. However, different drivers had very different preferences with respect to what type of information they found useful. The majority of the participants preferred simple and clear information. The eco-driving constituents that were rated as most useful were advice on gas pedal pressure, speed guidance, feedback on manoeuvres, fuel consumption information and simple statistics. It is concluded that customisable user interfaces are recommended for eco-driving support systems for trucks.

  • 43.
    Jansson, Andreas
    et al.
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Körsimulering och visualisering, SIM.
    Ahlström, Christer
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Trafikanttillstånd, TIL.
    Linking gaze tracking with a simulated world2017Rapport (Annet vitenskapelig)
    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.

  • 44.
    Jägerbrand, Annika
    et al.
    Statens väg- och transportforskningsinstitut, Samhälle, miljö och transporter, SAMT, Miljö, MILJÖ.
    Antonson, Hans
    Statens väg- och transportforskningsinstitut, Samhälle, miljö och transporter, SAMT, Mobilitet, aktörer och planering, MAP.
    Ahlström, Christer
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Trafikanttillstånd, TIL.
    Speed reduction effects over distance of animal-vehicle collision countermeasures: a driving simulator study2018Inngår i: European Transport Research Review, ISSN 1867-0717, E-ISSN 1866-8887, Vol. 10, nr 2, artikkel-id 40Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 45.
    Kircher, Katja
    et al.
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Ahlström, Christer
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Can we trust driver behaviour assessment?: Examples from research in simulators and in the field2012Inngår i: Proceedings of Measuring Behavior 2012 (Utrecht, The Netherlands, August 28-31, 2012) / [ed] A.J. Spink, F. Grieco, O.E. Krips, L.W.S. Loijens, L.P.J.J. Noldus, and P.H. Zimmerman, Utrecht, NL, 2012, s. 55-58Konferansepaper (Fagfellevurdert)
    Abstract [en]

    It is very common to compare mean values of driving performance indicators (PI) like mean speed, the standard deviation of lateral position, time headway, mean glance duration, and many more, in order to investigate possible differences between different treatment groups. Just like all the PIs mentioned here, most of them describe aspects of the control level of driving behaviour according to Michon’s control hierarchy. When means differ significantly between treatment groups, this is often interpreted in relation to traffic safety gains or losses.

    In this paper we are going to discuss possible pitfalls with the use and interpretation of such performance indicators, based on examples from studies carried out in driving simulator and in the field. Finally, we suggest a number of possible solutions to avoid some of the issues discussed here.

  • 46.
    Kircher, Katja
    et al.
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Trafikanttillstånd, TIL.
    Ahlström, Christer
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Trafikanttillstånd, TIL.
    Evaluation of methods for the assessment of attention while driving2017Inngår i: Accident Analysis and Prevention, ISSN 0001-4575, E-ISSN 1879-2057Artikkel i tidsskrift (Fagfellevurdert)
    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. .

  • 47.
    Kircher, Katja
    et al.
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Trafikanttillstånd, TIL.
    Ahlström, Christer
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Trafikanttillstånd, TIL.
    Evaluation of methods for the assessment of attention while driving2016Konferansepaper (Fagfellevurdert)
    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.

  • 48.
    Kircher, Katja
    et al.
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Ahlström, Christer
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Evaluation of methods for the assessment of minimum required attention2015Rapport (Annet vitenskapelig)
    Abstract [en]

    The empirical methods eye tracking while driving, visual occlusion while driving, think aloud while driving, expert judgement in the laboratory and think aloud while watching video are evaluated for their usefulness to assess driver attention in real traffic. Using a within-subjects design, six driving instructors drove three 14-kilometre-laps on a motorway per driving condition. Additional participants took part in sub-sets of the conditions. The methods were evaluated both with respect to practical implications and to the results that could be obtained with them. Glance behaviour and self-paced visual occlusion varied between different manoeuvre types (lane change – two directions, driving in left or right lane) and also between drivers. For the assessment of the attentional requirements of different traffic situations it is recommended to identify “situational prototypes” and related manoeuvres. The attention assessment should then be made with eye tracking in combination with visual occlusion, complemented with the think aloud technique. It is important to consider inter-individual variations in the process of identifying general attentional requirements for a prototypical situation/manoeuvre combination. Information about surrounding traffic needs to be obtained for a correct assessment. Preliminary results indicate that it is important to adopt a manoeuvre-oriented view, for example when identifying visual targets, instead of using a static gaze target classification scheme.

  • 49.
    Kircher, Katja
    et al.
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Ahlström, Christer
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Issues related to the driver distraction detection algorithm AttenD2009Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Driver distraction is a contributing factor to many crashes and a real-time distraction warning system has the potential to mitigate or circumvent many of these crashes. The objective of this paper is to thoroughly describe the distraction detection algorithm AttenD and explain the theory underlying different design choices. Future aspects and distraction warning strategies will be discussed as well.

    In summary, AttenD is an eye-tracker based distraction detection algorithm which identifies visual distraction in real-time based on single long glances as well as repetitive glances. The core idea of the algorithm is a 2-second time buffer which is decremented when the driver looks away from the road and incremented when the driver looks back at the road. If the buffer runs empty, the driver’s state is classified as distracted.

  • 50.
    Kircher, Katja
    et al.
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Trafikanttillstånd, TIL.
    Ahlström, Christer
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Trafikanttillstånd, TIL.
    Minimum Required Attention: A Human-Centered Approach to Driver Inattention2017Inngår i: Human Factors, ISSN 0018-7208, E-ISSN 1547-8181, Vol. 59, nr 3, s. 471-484Artikkel i tidsskrift (Fagfellevurdert)
    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.

12 1 - 50 of 77
RefereraExporteraLink til resultatlisten
Permanent link
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf