The influence of hearing loss on transport safety and mobility

Purpose: To examine how road users with different degree of hearing loss experience safety and mobility in transport situations, compared to road users with normal hearing.Methods: A questionnaire ... Document type: Articl

Interaction between Cyclists and Motor Vehicles : the role of infrastructure design and vehicle characteristics

The aim of the project was to examine interactions between motor vehicle drivers and cyclists at intersections and the impact of infrastructure design and motor vehicle characteristics on interactive behaviour. The project activities included literature reviews on cycling infrastructure at intersections, vehicle driver behaviour and cyclist behaviour; questionnaires among motor vehicle drivers and cyclists across different cities in Sweden; field observations to investigate what cues cyclists use to interpret the intention of motor vehicles they interact with at signalised intersections; on-site interviews with cyclists to explore their strategy in an encounter with a motor vehicle; and a cycling simulator study to examine the behaviour of cyclists when approaching an intersection and the factors that may influence their decisions. The findings confirm that the way the cycling infrastructure is designed at intersections contributes to how cyclists and motor vehicles interact. Placing cyclists and motor vehicle drivers close (where they are visible to one another) at intersection areas increases the level of presence-awareness for both road users and consequently it increases safety. Though cyclists may feel more uncomfortable (exposed and unsafe) with this solution, they tend to be more careful and attentive. This finding from the literature was confirmed by the field observations showing that mixed traffic, i.e. “no cycle facility” at the intersection is the safest solution and the cycle lane solution is the least safe one. However, the on-site interviews with cyclists revealed that the large majority of the respondents preferred the infrastructure solution with a separated bicycle path. This is a typical case where objective safety and subjective safety stand in opposite relationship. The findings also revealed that one-directional cycle tracks enhance interaction at intersections, since motor vehicle drivers only expect cyclists from one direction. However, cyclists not following the rule and riding against the prescribed direction create problems and conflictive situations. Cyclists and the way they use the road infrastructure were found to be highly heterogeneous; the availability of cycling infrastructure at an intersection does not guarantee that cyclists use it as expected by designers and perhaps by motor vehicle drivers, as the infrastructure solution in some cases might not provide the shortest path for the cyclist. The uncertainty in cycling behaviour was found to be more at intersections with no cycling infrastructure. Confidence level among cyclists was found to affect their interaction with motor vehicles which tends to be hard for motor vehicle drivers to predict as different cyclists behave differently depending on their confidence in traffic.The majority of the interviewed cyclists said that when arriving at an intersection just after a motor vehicle they usually pass it on its right side. This was seen in observations on sites with cycle lane or cycle path but not on sites with mixed traffic. Also, if the motor vehicle was a heavy vehicle (bus or truck), somewhat fewer cyclists passed it on its right side. Also the cycling simulator study revealed that the most significant difference of longitudinal stop position was between the condition of a narrow lane without cycle lane marking and a truck standing at the stop line and the condition of wide lane with cycle lane marking and a car standing at the stop line, where the average stop position of the cyclist was behind the truck in the first condition and next to the car in the second condition. This finding corresponds to the test cyclists’ verbal expressions of the importance of “being visible and avoiding the blind spot”. The increased caution associated with the presence of a truck is motivated and in line with previous studies. At sites with mixed traffic (no cycle facility), compared to with cycle lane or cycle path, the cyclists’ scanning behaviour was more complete. At sites with cycle path, the cyclists looked for eye contact with the driver of the motor vehicle to a much larger extent than cyclists at the other two types of sites. Cyclists at sites with mixed traffic (no cycle facility) were more active in their visual search behaviour than cyclists at the other two types of sites. Also, those cyclists who passed the motor vehicle on its right side were more active in their visual search behaviour than those who did not pass the motor vehicle. The share of critical situations indicates that sites with mixed traffic (no cycle facility) is the safest solution and cycle lane solution is the least safe one

Electrooculogram analysis and development of a system for defining stages of drowsiness

Electrooculogram (EOG) analysis has been used to detect drowsiness stages, using data from experiments performed in the VTI driving simulator. The suitability of the existing method for blink detection in the EOG signal was evaluated in a preliminary study. Longer blinks recognized in the signal were compared to those identified in video recordings from the same experiment. All long blinks were not found in the signal, but still enough to consider data appropriate. The method to detect drowsiness is based on a linear relationship between blink amplitude and velocity, a method used and defined by Hargutt and Krüger. Self ratings of the drowsiness from the driving session, as defined into nine levels, were reduced into four. These were used to determine the detection boundaries for the program. The MATLAB program has shown correspondence with the converted sleepiness ratings. Out of six subjects, five showed a correspondence greater than 75%. This demonstrates the possibility of applying the amplitude- and velocity linearity on EOG data and an appropriate adjustment of the self ratings to the four sleepiness stages.Master's thesis project in biomedical engineering, reprint from Linköping University, Dept. Biomedical Engineering, LiU-IMT-Ex-351, Linköping 2003</p

Effekter av hörselnedsättning på trafiksäkerhet och mobilitet

The aim of this PhD thesis was to investigate traffic safety and mobility for individuals with hearing loss (HL). Three studies were conducted: 1. a questionnaire survey aimed to evaluate differences in choice of transportation that might be related to HL, 2. a driving simulator study that looked into compensatory strategies and evaluated the efficiency of a tactile signal to alert the driver, and 3. a field study to evaluate these effects in real traffic and to evaluate a navigation system with a supportive tactile signal. The effects of HL discovered in this thesis add to the knowledge and understanding of the influence of HL on traffic safety and mobility. Differences found consistently point to a generally more cautious behavior. Compensatory and coping strategies associated with HL are bound to driving complexity and appear when complexity increases. These strategies include driving at lower speeds, using a more comprehensive visual search behavior and being less engaged in distracting activities. Evaluation of a tactile signal showed that by adding a tactile modality, some driver assistance systems can also be made accessible to drivers with HL. At the same time, the systems might be more effective for all users, since the driver can be more focused on the road. Based on the results in this thesis, drivers with HL cannot be considered an increased traffic safety risk, and there should be no need for adjustments of the requirements of hearing for a license to drive a car.Syftet med den här doktorsavhandlingen var att undersöka trafiksäkerhet och mobilitet för individer med hörselnedsättning (HN). Tre studier har genomförts: 1. en enkätstudie för att undersöka skillnader i transportvanor relaterade till HN, 2. en körsimulatorstudie for att titta på kompensatoriska strategier och utvärdera effektiviteten i en taktil signal för att påkalla förarens uppmärksamhet och 3. en fältstudie för att undersöka effekterna i riktig trafik samt utvärdera ett navigationssystem med en taktil signal som stöd för navigering. Effekterna av HN som kom fram i denna avhandling bidrar till kunskapen och förståelsen för hur HN påverkar trafiksäkerhet och mobilitet. De funna skillnaderna pekar konsistent mot ett generelltmera försiktigt beteende. Kompensatoriska - och copingstrategier förknippade med HN beror på körkomplexitet och observeras när komplexiteten ökar. Dessa strategier innebär körning med lägre hastighet, mera heltäckande visuell avsökning och mindre engagemang i distraherande uppgifter. Utvärdering av en taktil signal visade att genom att lägga till en taktil modalitet kan vissa förarstödsystem bli tillgängliga även för förare med HN. Samtidigt kan systemen bli mera effektiva för alla användare eftersom föraren då kan fokusera mera på vägen. Baserat på resultaten i den här avhandlingen kan inte förare med HN betraktas som någon förhöjd risk och det bör därmed inte finnas något behov av att justera hörselkraven när det gäller körkortsinnehav

Effekter av hörselnedsättning på trafiksäkerhet och mobilitet

The aim of this PhD thesis was to investigate traffic safety and mobility for individuals with hearing loss (HL). Three studies were conducted: 1. a questionnaire survey aimed to evaluate differences in choice of transportation that might be related to HL, 2. a driving simulator study that looked into compensatory strategies and evaluated the efficiency of a tactile signal to alert the driver, and 3. a field study to evaluate these effects in real traffic and to evaluate a navigation system with a supportive tactile signal. The effects of HL discovered in this thesis add to the knowledge and understanding of the influence of HL on traffic safety and mobility. Differences found consistently point to a generally more cautious behavior. Compensatory and coping strategies associated with HL are bound to driving complexity and appear when complexity increases. These strategies include driving at lower speeds, using a more comprehensive visual search behavior and being less engaged in distracting activities. Evaluation of a tactile signal showed that by adding a tactile modality, some driver assistance systems can also be made accessible to drivers with HL. At the same time, the systems might be more effective for all users, since the driver can be more focused on the road. Based on the results in this thesis, drivers with HL cannot be considered an increased traffic safety risk, and there should be no need for adjustments of the requirements of hearing for a license to drive a car.Syftet med den här doktorsavhandlingen var att undersöka trafiksäkerhet och mobilitet för individer med hörselnedsättning (HN). Tre studier har genomförts: 1. en enkätstudie för att undersöka skillnader i transportvanor relaterade till HN, 2. en körsimulatorstudie for att titta på kompensatoriska strategier och utvärdera effektiviteten i en taktil signal för att påkalla förarens uppmärksamhet och 3. en fältstudie för att undersöka effekterna i riktig trafik samt utvärdera ett navigationssystem med en taktil signal som stöd för navigering. Effekterna av HN som kom fram i denna avhandling bidrar till kunskapen och förståelsen för hur HN påverkar trafiksäkerhet och mobilitet. De funna skillnaderna pekar konsistent mot ett generelltmera försiktigt beteende. Kompensatoriska - och copingstrategier förknippade med HN beror på körkomplexitet och observeras när komplexiteten ökar. Dessa strategier innebär körning med lägre hastighet, mera heltäckande visuell avsökning och mindre engagemang i distraherande uppgifter. Utvärdering av en taktil signal visade att genom att lägga till en taktil modalitet kan vissa förarstödsystem bli tillgängliga även för förare med HN. Samtidigt kan systemen bli mera effektiva för alla användare eftersom föraren då kan fokusera mera på vägen. Baserat på resultaten i den här avhandlingen kan inte förare med HN betraktas som någon förhöjd risk och det bör därmed inte finnas något behov av att justera hörselkraven när det gäller körkortsinnehav

Automatisering kontra manuell provning : potentiella vinster vid minskning av den mänskliga faktorn

Inom avancerad produktionsindustri använder man sig fortfarande i stor utsträckning av manuell provning för att säkra kvaliteten på de tillverkade produkterna. Detta innebär, förutom att man ofta bara tar stickprov, även en viss fördröjning innan upptäckt av eventuella kvalitetsbrister. Dessutom finns en osäkerhetsfaktor härrörande från den mänskliga faktorn eftersom människans kognitiva förmågor påverkas av dagsform, stressupplevelse, personliga erfarenheter med mera. Examensarbetet har utförts vid Linköpings universitet inom ramen för en magisterutbildning i Ergonomi och MTO (Människa Teknik Organisation). Syftet är att undersöka potentiella vinster vid minskning av den mänskliga faktorn vid övergång från manuell till automatiserad OFP (oförstörande provning). Arbetet består av en litteraturstudie, enkäter till operatörer samt intervjuer med beslutsfattare. Vid detektering, lokalisering, särskiljning, jämförelse och kategorisering spelar perceptionen en stor roll. Den mänskliga faktorn är ett av de huvudelement som påverkar kvaliteten vid oförstörande provning. Operatören är således den största källan till tillförlitlighetsvariation (Dickens &amp; Bray, 1994). OFP - utrustningen visar bara rätt information om den hanteras korrekt. Dessutom behöver informationen tolkas och sammanställas för att en bedömning ska kunna göras. Åtskilliga studier har visat låg detekteringsgrad för flera olika OFP - metoder (runt 50 %) och flera storskaliga forskningsprogram har visat att automatiserad provning är överlägsen den manuella (PISC, NORDEST, NIL, ICON, TIP). Flera studier har visat högre detekteringsgrad (84-90 % jämfört med 50-52 %) och lägre kostnader (minskning med ca 40 %) vid automatisering av provningen. (Wassink &amp; Dijkstra, 2007, Verkooijen, 1998). Knappt 70 operatörer i tillverkningsindustrin har deltagit i denna studie genom att fylla i en enkät om sin arbetssituation. Operatörerna tror själva att stress, trötthet, monotonitet och distraktion i nämnd ordning har negativ påverkan på detekteringsgraden. 97 % av dem tror att automatisering av moment skulle öka andelen funna fel.   Fem beslutsfattare inom olika tillverkningsindustrier har deltagit i studien genom intervjuer kring varför man valt att automatisera. Beslutsfattarna nämner ekonomi och kvalitet som främsta orsaker till att man valt att automatisera provningen. Flera anser att felfrekvensen vid manuell provning var för hög för att man skulle kunna leva upp till kvalitetskraven. Även ergonomi har spelat in eftersom man sparat mycket pengar på minskad sjukfrånvaro. Provningen anses bli mer heltäckande och dokumentationen bättre. Flera uppskattar tids- och kostnadsbesparingar till minst 60 %. Samtliga är nöjda med övergången och kommer att fortsätta automatisera flera moment.In advanced production industry manual testing is still a common method for ensuring quality of manufactured products. This means apart from the fact that it is often a spot check also a certain delay before possible quality problems are discovered. Additionally there is an uncertainty due to the human factor since the human cognitive behavior is affected by day form, experienced stress, and personal practice etcetera.   This thesis has been carried out at the University of Linköping as a part of a Master in ergonomics degree. The aim is to investigate potential benefits due to less influence of the human factor, when shifting from manual to automated NDT (non destructive testing). The work includes a literature review, operator questionnaires and interviews with decision makers.   At detection, localization, separation, comparison and categorization human perception is of great importance. The human factor is one of the main elements affecting the quality of nondestructive testing. The operator therefore is the main source of reliability variations. The NDE equipment only shows the right information if it is handled the right way. In addition the information needs to be interpreted and put together for an assessment to be made.   Several studies have shown low detection rate for various NDT methods (around 50 %) and a number of large-scale research programs have shown that automated testing is superior to manual (PISC, NORDEST, NIL, ICON, TIP). Various studies have shown higher detection rate (84-90 % compared to 50-52 %) and lower costs (reduction of approx. 40 %) by automation of the testing (Wassink &amp; Dijkstra, 2007, Verkooijen, 1998).   Almost 70 operators in the manufacturing industry took part in this study by answering a questionnaire about their working situation. The operators themselves believe that stress, drowsiness, monotony and distraction, in the order mentioned, have negative effect on the detection rate. 97 % of them think that by automating some elements, the detection rate would increase.   Five decisions makers in the manufacturing industry took part in the study thru interviews concerning the reason for automating the testing. The decisions makers mention economy and quality as main reasons for choosing changeover to automation. Several think that the error frequency by manual testing is too high to be able to live up to the quality demands. Also ergonomics have played a big role since they have saved a lot of money due to less reporting sick. The testing is believed to be more comprehensive and the documentation better. Several estimate time and cost savings to be at least 60 %. All are satisfied with the changeover and want to automate more elements of the production

Effekter av hörselnedsättning på trafiksäkerhet och mobilitet

The aim of this PhD thesis was to investigate traffic safety and mobility for individuals with hearing loss (HL). Three studies were conducted: 1. a questionnaire survey aimed to evaluate differences in choice of transportation that might be related to HL, 2. a driving simulator study that looked into compensatory strategies and evaluated the efficiency of a tactile signal to alert the driver, and 3. a field study to evaluate these effects in real traffic and to evaluate a navigation system with a supportive tactile signal. The effects of HL discovered in this thesis add to the knowledge and understanding of the influence of HL on traffic safety and mobility. Differences found consistently point to a generally more cautious behavior. Compensatory and coping strategies associated with HL are bound to driving complexity and appear when complexity increases. These strategies include driving at lower speeds, using a more comprehensive visual search behavior and being less engaged in distracting activities. Evaluation of a tactile signal showed that by adding a tactile modality, some driver assistance systems can also be made accessible to drivers with HL. At the same time, the systems might be more effective for all users, since the driver can be more focused on the road. Based on the results in this thesis, drivers with HL cannot be considered an increased traffic safety risk, and there should be no need for adjustments of the requirements of hearing for a license to drive a car.Syftet med den här doktorsavhandlingen var att undersöka trafiksäkerhet och mobilitet för individer med hörselnedsättning (HN). Tre studier har genomförts: 1. en enkätstudie för att undersöka skillnader i transportvanor relaterade till HN, 2. en körsimulatorstudie for att titta på kompensatoriska strategier och utvärdera effektiviteten i en taktil signal för att påkalla förarens uppmärksamhet och 3. en fältstudie för att undersöka effekterna i riktig trafik samt utvärdera ett navigationssystem med en taktil signal som stöd för navigering. Effekterna av HN som kom fram i denna avhandling bidrar till kunskapen och förståelsen för hur HN påverkar trafiksäkerhet och mobilitet. De funna skillnaderna pekar konsistent mot ett generelltmera försiktigt beteende. Kompensatoriska - och copingstrategier förknippade med HN beror på körkomplexitet och observeras när komplexiteten ökar. Dessa strategier innebär körning med lägre hastighet, mera heltäckande visuell avsökning och mindre engagemang i distraherande uppgifter. Utvärdering av en taktil signal visade att genom att lägga till en taktil modalitet kan vissa förarstödsystem bli tillgängliga även för förare med HN. Samtidigt kan systemen bli mera effektiva för alla användare eftersom föraren då kan fokusera mera på vägen. Baserat på resultaten i den här avhandlingen kan inte förare med HN betraktas som någon förhöjd risk och det bör därmed inte finnas något behov av att justera hörselkraven när det gäller körkortsinnehav

Körsimulatorer i förarutbildningen : trafiklärares upplevelse av simulatorns nytta och betydelse

Syftet med projektet var att få en bättre insyn i hur trafiklärare upplever simulatorns möjligheter och nytta under körkortsutbildningen. Detta med bakgrund av att intresset för simulatorer på senare år har ökat i Sverige. Lägre inköpskostnad och mer realistiska scenarier som passar för körkortsutbildning är några förklaringar. Trots detta är det fortfarande relativt få trafikskolor som använder simulatorer som ett komplement till övriga pedagogiska verktyg. Deras erfarenhet behövs dock för att få bättre kunskap kring simulatorernas användbarhet och hur metodiken eventuellt bör utvecklas för ett mer systematiskt och gemensamt arbetssätt över landet. Totalt intervjuades 14 trafiklärare som använde simulator för utbildning inom tung trafik och/eller för personbil

Effects of ADHD on driver attention and speed, evaluated in a driving simulator

Drivers with Attention Deficit Hyperactivity Disorder (ADHD) have been considered to have a 3–4 times higher crash risk than control drivers without ADHD. A core issue which has not been properly dealt with is the role of comorbid diagnoses which frequently appear together with ADHD, especially Oppositional Defiant Disorder (ODD) and Conduct Disorder (CD), sometimes generically referred to as “conduct problems”. The increased crash risk associated with ADHD diagnosis presented in the literature is often based on studies performed with participants with more than one diagnosis. This means that the comorbidity may be high and, consequently, the effect of ADHD on traffic safety may be overestimated. This has been shown in a meta-analysis presenting a relative risk of 1.30 instead. The existing research on drivers with ADHD is unsatisfying when it comes to methodology, specifically concerning inclusion and exclusion criteria for participants. This has led to a misunderstanding of the driving ability for people with ADHD, which has been cited and spread in the literature for two decades. People with ADHD diagnosis might suffer from this misinterpretation and the specific effects of ADHD on driving behavior remain unclear. There is a potential for better control for confounding factors, for exposure (mileage) and for comorbidity, especially CD and ODD. The aim of this study was to examine differences in driving behavior between experienced drivers with and without ADHD, respectively

Vision measurability and its impact on safe driving : a literature review

Knowledge of measurability of vision and its impact on safe driving have been proven to be important to secure a safe traffic system. Several different approaches to measuring visual function in order to improve road safety have been identified around the world. A trend seen in the literature is that traditional vision tests are increasingly supplemented by cognitive tests. The purpose of this study was to provide an overview of visual capabilities that are important for safe driving. The study answered questions about the visual capabilities that are essential for safe driving; which tests are available and how they are used; and existing evidence for these tests. The literature review was based on database searches of TRID, Web of Science and PubMed. In total 128 scientific publications were included in the overview. The results provided an overview of international standards of vision required for driving a car. Moreover, the results were structured according to the different visual capabilities and a corresponding account of the diseases that may affect these capabilities; available tests and corroborating evidence for the test; and the manner in which these capabilities are important for safe driving. Two tests were highlighted based on the review: contrast sensitivity, and Useful Field of View. It was also concluded that 1) testing of vision should consist of several complementary tests, 2) good visual acuity is not alone sufficient for safe driving, and 3) tests including cognitive aspects can complement vision testing and improve the assessment of safe driving.Kunskap om synförmågans mätbarhet och inverkan på bilkörning har visat sig vara av vikt för att trygga ett säkert trafiksystem. Flera olika ansatser till att mäta synförmågan i syfte att förbättra trafiksäkerheten har identifierats runt om i världen. En trend som setts är att traditionella syntester alltmer kompletterats med kognitiva tester. Syftet med den här studien var att ge en översikt över synförmågor som är viktiga för säker bilkörning. Studien besvarade frågor om egenskaper i synen, viktiga för säker bilkörning, vilka tester som finns och hur dessa används, samt vilken evidens som finns för olika tester. Litteraturöversikten vilade på resultat från sökningar gjorda i databaserna TRID, Web of Science och PubMed. Totalt inkluderades 128 vetenskapliga publiceringar i översikten. Resultaten bereder en översyn av internationella krav på synförmågan som ställs för privata bilförare. Vidare presenteras resultat uppdelat utifrån olika synförmågor där dessa beskrivs tillsammans med en översikt av sjukdomar som kan påverka förmågan, vilka tester som finns och dess evidens, samt hur förmågan inverkar på säker bilkörning. Två tester lyftes fram utifrån dessa starka stöd i litteraturen och dessa var (1) kontrastkänslighet och (2) Useful Field of View. Utifrån resultatet drogs slutsatsen att testning av synförmåga bör bestå av kompletterande tester, att de mest förekommande måtten på synskärpa inte är tillräckligt för att säkerställa säker bilkörning, samt att tester som inrymmer kognitiva aspekter kan komplettera bedömningen av synförmågan