During impact driving of open-ended piles through cohesion-less soil the internal soil column may mobilize enough internal shaft resistance to prevent new soil from entering the pile. This phenomena, referred to as soil plugging, changes the driving characteristics of the open-ended pile to that of a closed-ended, full displacement pile. If the plugging behavior is not correctly understood, the result is often that unnecessarily powerful and costly hammers are used because of high predicted driving resistance or that the pile plugs unexpectedly such that the hammer cannot achieve further penetration. Today the user is generally required to model the pile response on the basis of a plugged or unplugged pile, indicating a need to be able to evaluate soil plugging prior to performing the drivability analysis and before using the results as basis for decision. This MSc. thesis focuses on soil plugging during impact driving of open-ended piles in cohesion-less soil and aims to contribute to the understanding of this area by evaluating models for predicting soil plugging and driving resistance of open-ended piles. Evaluation was done on the basis of known soil plugging mechanisms and practical aspects of pile driving. Two recently published models, one for predicting the likelihood of plugging and the other for predicting the driving resistance of open-ended piles, were compared to existing models. The main outcomes from the model evaluations are: • Internal shaft resistance, pile diameter and pile velocity/acceleration were found to be the primary input parameters affecting the result in the models used to predict if soil plugging is likely to occur. • The pile diameter was shown to have less influence on the calculated driving resistance in the recently published model, derived from measurements of plug length ratios, compared to in the existing model. This thesis also includes a full-scale field study conducted during the initial piling operations for the construction of the new Värtahamnen seaport in Stockholm (Sweden). The soil conditions cause the piles to be driven through very dense post glacial moraine, in which little is known about soil plugging. The drivability performance of 146 open-ended and closed-ended steel pipe piles with diameters ranging from 914-1168 mm was compared through analysis of driving records. The aim was to evaluate if open-ended piles resulted in a drivability related gain and if so during which part of the installation process. The driving records were used to quantify the performance in terms of driving time and energy required to drive the piles. The main conclusions from the field study are: • Significant time savings were achieved by using open-ended piles instead of closedended piles. The time advantage was bigger during impact driving, compared to vibratory driving, and on average the impact driving of open-ended piles took 9 minutes versus 26 minutes for closed-ended piles. • Contrary to what was expected, namely that the open-ended piles would result in lower driving resistance, the results indicate that the majority of the time savings came from open-ended piles being more stable during driving and thereby requiring fewer adjustments. / Under slagdrivning av öppna pålar i friktionsjord förekommer det att den interna jordpelaren mobiliserar tillräckligt mycket internt mantelmotstånd för att förhindra inträngning av ny jord. Detta fenomen, på svenska vanligen kallat jordpluggning, medför att drivbeteendet för pålen övergår till att likna det hos en sluten och massundanträngande påle. Oförmåga att på ett korrekt sätt beakta jordpluggning medför ofta att drivmotståndet för öppna pålar antingen överskattas, vilket medför att onödigt kraftfull och kostsam utrustning används, eller underskattas vilket kan medföra att pålen pluggar och inte kan drivas till avsett djup. I dagsläget kräver drivbarhetsanalyser generellt sett att användaren måste modellera pålen som en pluggad eller opluggad påle. Detta medför att det finns ett behov att kunna utvärderajordpluggning innan drivbarhetsanalysen genomförs, samt även vid utvärdering av resultaten från drivbarhetsanalysen. Detta examensarbete fokuserar på jordpluggning vid slagdrivning av öppna pålar i friktionsjord och syftar till att öka kunskapen inom området genom att utvärdera modeller som kan användas för att uppskatta huruvida jordpluggning är sannolikt, samt modeller för att uppskatta drivmotståndet för öppna pålar. Utvärderingen av nämnda modeller skedde med utgångspunkt i kända mekanismer som förknippas med jordpluggning, samt i praktiska aspekter av påldrivning. Två nyligen publicerade modeller, en avsedd att utvärdera huruvida pluggning är sannolikt och den andra för att uppskatta det förväntade drivmotståndet, jämfördes med befintliga modeller för samma ändamål. De huvudsakliga slutsatserna av modellutvärderingen är: • Internt mantelmotstånd, pålens diameter samt pålens hastighet/acceleration var de faktorer som hade störst inverkan på resultatet hos de modeller som avser utvärdera huruvida jordpluggning är att förvänta. • Pålens diameter visade sig få mindre inverkan på beräknat drivmotstånd i den nyligen publicerade modellen, baserad på mätningar av plugglängd relativt penetrationsdjup, jämfört med i den befintliga modellen. Examensarbetet innefattar även en fältstudie genomförd under inledningen av pålningsarbetet vid uppförandet av nya Värtahamnen i Stockholm. Markförhållandena på platsen medför att pålarna drivs genom bottenmorän, ett jordförhållande där det i stor utsträckning saknas erfarenheter relaterade till jordpluggning. Med hjälp av pålprotokoll jämfördes drivbarheten hos 146 öppna och slutna pålar med diametrar 914-1168 mm. Målet var att fastställa huruvida öppna pålar medförde ökad drivbarhet och i så fall under vilket skede av drivprocessen. Pålprotokollen användes för att kvantifiera vinsten i form av drivtid samt erforderlig drivenergi. De huvudsakliga slutsatserna från fältstudien är: • Betydande tidsvinst kunde påvisas för öppna pålar, jämfört med stängda pålar. Tidsvinsten var större under slagdrivning än under vibrationsdrivning och i snitt 9 minuter jämfört med 26 minuter för stängda pålar. • I motsats till det förväntade utfallet, nämligen att de öppna pålarna inte skulle plugga, antyder resultaten att majoriteten av tidsvinsten kan kopplas till att de öppna pålarna var mer stabila under drivning vilket resulterade i färre korrigeringar

Driving anxiety that has developed following crashes has been studied relatively frequently, but anxiety per se and its effects on driving has not as yet garnered much attention in the literature. The current study included 1121 participants and found higher levels of general anxiety were related to a wide variety of dangerous driving behaviors. While there were clear and expected sex differences on many dangerous driving variables, there were still more such differences with regard to anxiety levels and independent of sex, higher levels of anxiety were associated with greater levels of dangerous driving. Of particular import, it was found that the high anxiety group had caused significantly more crashes and engaged in more DUI episodes than the low and/or medium anxiety groups. Taken as a whole, the results suggest there is a tremendous need for more research in the area of anxiety and dangerous driving and that interventions for highly anxious drivers may well be warranted.

A principal axis factor analysis with promax rotation yielded four factors, or joint variations between the 20 items, that were inter-correlated with eigenvalues greater than 1. The ADBQ was also found to have high internal consistency (Cronbach's alpha = .86). The four factors were used to form four subscales of aggressive driving behavior that included anger/aggression, speeding/minor infractions, overt expression, and judgment of other drivers. The four subscales were found to correlate with self-reported biographical and driver history data, as well as, gender differences across scales. Additional analyses were conducted using data from the present sample from the University of Central Florida (N = 285) and the data from the previous study from Old Dominion University (N = 230) and Michigan Technological University (N = 265) for a combined sample of 780 undergraduate students. The findings in this present study provided additional support for the consistency, predictive validity, and factor structure of the ADBQ instrument. The Aggressive Driving Behavior Questionnaire proves to be a valuable measure in predicting the likelihood of a person engaging in aggressive driving behavior. The implications for driving behavior assessment, training, and instrument development are also discussed.; Over the past decade, aggressive driving behavior has become a topic of concern among the public, media, and researchers in the psychological community. Aggressive driving is a problematic pattern of social behavior that is not only a leading cause to motor vehicle accidents, but a serious threat to public safety. One instrument that has been developed to assess aggressive driving behavior is the Aggressive Driving Behavior Questionnaire (ADBQ). The ADBQ is a 20-item paper and pencil questionnaire intended to measure a driver's likelihood for engaging in aggressive driving behavior. The ADBQ was developed using a factor-analytic approach that combined five previously developed aggressive driving behavior scales (Brill, Mouloua & Shirkey, 2007). Of the 81 items of the five combined scales, nineteen latent variables were extracted and accounted for 67.4% of the explained variance for the observed responses. The final 20th item was developed by splitting one of the latent variables. A previous study, conducted at Old Dominion University (N = 230) and Michigan Technological University (N = 265), examined the ADBQ's factor structure and internal consistency, and found relatively high internal consistency (Cronbach's alpha = .77) and the identification of six factors using a principal axis factor analysis (Brill & Mouloua, 2011). The ADBQ was also tested in a controlled laboratory environment and found significant evidence that suggest the ADBQ is a valid predictor of aggressive driving behavior in a simulated environment (Brill, Mouloua & Shirkey 2009). The purpose of the present study was to further investigate the psychometric properties of the ADBQ. Based on a sample of 285 undergraduates (170 women and 115 men) from the University of Central Florida, the study examined the internal consistency, predictive and construct validity, and factor structure of the new questionnaire.

Within the last few decades there has been an abundant increase in the amount of violent video games and movies shown within the media. Many of these violent videogames and movies include reckless driving behaviors or certain car scenarios that engross the viewer into wishing to imitate the actions they see on the screen. With that being said, majority of these viewers are adolescents or emerging adults who are beginning to drive and are prone to replicating what they see as adequate driving behaviors. The intent of this thesis is to indicate whether or not the amount of risky driving behaviors an adolescent or emerging adult is exposed to, the more likely they are to replicate these scenarios. Through the UCF sona system participants answered questions related to risky driving behaviors, safety habits, and how often they viewed or played certain videogames and movies. Overall, the results of the study indicate that participants exposed to risky driving behaviors in the media replicate these actions themselves. Further research and results should be taken into effect in order to raise awareness among adolescents and emerging adults who are at their early stages of driving.

Nowadays, autonomous driving revolution is getting closer to reality. To achieve the Autonomous driving the first step is to develop the Advanced Driver Assistance System (ADAS). Driver-assistance systems are one of the fastest-growing segments in automotive electronics since already there are many forms of ADAS available. To investigate state of art of development of ADAS towards Autonomous Driving, we develop Systematic Mapping Study (SMS). SMS methodology is used to collect, classify, and analyze the relevant publications. A classification is introduced based on the developments carried out in ADAS towards Autonomous driving. According to SMS methodology, we identified 894 relevant publications about ADAS and its developmental journey toward Autonomous Driving completed from 2012 to 2016. We classify the area of our research under three classifications: technical classifications, research types and research contributions. The related publications are classified under thirty-three technical classifications. This thesis sheds light on a better understanding of the achievements and shortcomings in this area. By evaluating collected results, we answer our seven research questions. The result specifies that most of the publications belong to the Models and Solution Proposal from the research type and contribution. The least number of the publications belong to the Automated…Autonomous driving from the technical classification which indicated the lack of publications in this area.

published_or_final_version / Sociology / Master / Master of Social Sciences

Det svenska förarprovet har vuxit fram ur praktisk yrkeserfarenhet. Oavsett vilken trafikinspektör som bedömer ett specifikt körprov ska bedömningen göras lika. Kognitiva egenskaper bedöms i körprovet genom att observera handlingar och beteenden. Syftet med denna uppsats var att ur ett teoretiskt perspektiv undersöka hur trafikinspektörer bedömer kognition, för att undersöka vilka likheter och skillnader som finns. Tre analyser gjordes utifrån tolv intervjuer med trafikinspektörer vid två av Vägverkets förarprovskontor. Trafikinspektörerna ombads beskriva vad som är viktigt hos en bilförare. Samtliga formella kriterier för körprovet nämndes av någon informant. Utöver kriterierna nämndes även många andra begrepp av ett fåtal personer vardera. Dessa begrepp kan räknas till områdena kognitionspsykologi, allmän psykologi, bilkörning och övergripande egenskaper. De tre mest nämnda begreppen var uppmärksamhet, erfarenhet och riskmedvetande. Sju körprovskriterier definierades av trafikinspektörerna. Många olika begrepp användes för att definiera kriterierna och samtliga kriterier definierades olika av informanterna. Definitionerna delades in i kategorier och de kategorier som användes för samtliga kriterier var förberedelser, handlingar och perception. Ur det som sades av informanterna gjordes en analys om hur begrepp kopplas samman med varandra, för att hitta alla associationer som görs till varje begrepp. Många olika kopplingar kunde hittas genom denna analys och av dessa nämndes hälften av enbart någon informant. Två kopplingar nämndes av elva av informanterna. Den ena var manövrering – automatisering, den andra var uppmärksamhet – syn. Studien påvisade både likheter och skillnader i åsikter informanterna emellan. I viss utsträckning använda sig informanterna av samma begrepp, men de lade olika innebörder i begreppen. Trafikinspektörernas olika synsätt medför en risk för att de bedömer körprov olika trots att de använder samma bedömningskriterier. / The Swedish driving license test has developed from practical professional experience. Regardless of which traffic inspector judges a specific driving test, the judgement is to be equal. Cognitive qualities are judged in the driving test by observing actions and behaviours. The purpose of this essay was to investigate, from a theoretical perspective, how traffic inspectors judge cognition, in order to investigate differences and similarities. Three analyses were made, based on twelve interviews with traffic inspectors working at two of the Swedish Road Administration’s offices for driving license tests. The traffic inspectors were asked to describe what is important in a car driver. All formal driving test criteria were mentioned by some informant. In addition to the criteria, many other concepts were mentioned by a few persons each. These concepts belong to the areas cognitive psychology, general psychology, car driving and overall qualities. The three most mentioned concepts, including criteria and other concepts, were attention, experience and risk awareness. Seven driving test criteria were defined by the traffic inspectors. Many different concepts were used to define the criteria and all criteria were defined differently by the informants. The definitions were divided into categories. The categories preparations, actions and perception were used for all criteria. An analysis about how concepts were connected to each other was made, in order to find all associations made with each concept. Many different connections were found in this analysis and more than half of these were mentioned by only one informant. Two connections were mentioned by eleven informants. One of these was manoeuvring – automation, the other was attention – vision. Both similarities and differences in opinions were found among the informants in this study. The informants used the same concepts to some extent, but they associated different meanings with the concepts. The traffic inspectors’ differences in opinions lead to a risk of judging driving tests differently, although the same judgement criteria are used.

Worldwide, motor accidents are responsible for a large number of deaths and disabilities (Connor et al., 2001), and one of the major causes of motor accidents is driver fatigue. Although majority of drivers are aware of the dangers of fatigued driving, accidents related to this continues to contribute to a large percentage of all accidents, between 5 and 50% (Nilsson et al., 1997; Williamson et al., 2011). The purpose of the research was to establish the effect that fatigue renders on an individual’s peripheral visual field and to determine whether a decrement in driving performance occurs at the same rate as a decrement in peripheral visual performance. Fatigue was induced through time of day as well as time on task. Sixteen students from Rhodes University were recruited, subject to no previous sleep disorders, among other criteria. Each participant was required to partake in two conditions, namely a day condition (09h00–11h00) and a night condition (23h00– 01h00). Each condition consisted of a 90 minute dual task; the primary task was a tracking task, in which participants were instructed to track a white line as accurately as possible. A secondary peripheral response task was introduced, in which participants were instructed to respond as quickly as possible to the peripheral stimuli, by pressing one of two clickers located on the steering wheel. The peripheral stimuli were located at 20º, 30º and 40º visual angle. Psychophysiological, performance and subjective measures were obtained before, during and after the main task. The pre- and post-tests included core body temperature, critical flicker fusion frequency threshold, a digit span memory test, Wits Sleepiness Scale and a NASA-TLX questionnaire. The psychophysiological and performance measures of heart rate, heart rate variability, blink frequency, blink duration, lane deviation, number of saccades towards peripheral stimuli, response time to peripheral stimuli and the percentage of missed peripheral responses were all recorded throughout the 90 minute main dual task. The results revealed significant differences (p<0.05) for heart rate variability, number of saccades towards peripheral stimuli and the Wits Sleepiness Scale, with regard to time of day. For time on task, significant effects were established for lane deviation, response time to peripheral stimuli, percentage of missed peripheral responses, heart rate, heart rate variability, blink frequency, blink duration, critical flicker fusion frequency threshold, core body temperature and the Wits Sleepiness Scale. Eccentricity was analysed and found to be significant for response time to peripheral stimuli, as well as for the percentage of missed peripheral responses; there was a significant increase in both measures with an increase in the stimuli eccentricity. No significances were established for time of day or between the pre- and post-tests conducted for the digit span memory performance; however, a significant interactional effect between the two was established. When assessing the percentage rate of decrement of driving performance compared to the percentage rate in the decrement of the missed peripheral responses, it was found that the percentage rate of decrement was equal for both measures. Thus from this research it can be seen that, concurrent with a decrement in driving performance, there are adverse effects on an individuals' peripheral vision, which have great implications for the safety of workers in industry and transport, as well as motorists. It was also established that time on task is possibly a more appropriate variable to consider than time of day, when implementing work schedules and rest breaks in industry, transport and fields alike, as more significant findings were seen for time on task compared to time of day. / Adobe Acrobat 9.53 Paper Capture Plug-in

The latest trends in autonomous vehicles research gave rise to the needs for specific tools to validate and test such systems. The estimations state that to consider an autonomous vehicle statistically safe, it should drive for thousands of kilometres using traditional validation methods. This process would take a long time. Furthermore, an update in the software, would require to re-run those kilometres. Therefore, the testing must be performed exploiting virtual simulations that should realistically reflect the real world. One way to perfor msuch simulations is to let the vehicle model drive down a road map and control the surrounding traffic. To be effective, spawned traffic should not be generated too far from the target vehicle. The OpenSCENARIO standard offers a feature restricting such traffic within an ellipse centred in the central object (target vehicle). This thesis investigated what technique was more efficient and scalable to detect viable roads within the ellipse to spawn stochastic traffic on. The explored solutions are two: an analytical approach and an adaptation of the AABB tree algorithm. The research started with simple cases and incremented the scenario’s complexity during the development. Through this methodology, each technique’s positive aspects and limits have been highlighted, allowing a comparison to be made. / De senaste trenderna i autonoma fordon har ökat behovet av specifika verktyg för att validera och testa sådana system. För att kunna betrakta ett autonomt fordon som statistiskt säkert, ska enligt uppskattningar autonoma fordon köra tusentals kilometer med traditionella valideringsmetoder. Denna process skulle ta mycket lång tid. Dessutom skulle en uppdatering i mjukvaran kräva att alla dessa tusentals kilometer att körs igen. Därför måste testningen utföras med hjälp av virtuella simuleringar som bör efterlikna den reella världen realistiskt. Ett sätt att genomföra dessa simuleringar är att låta en autonom fordonsmodell köra genom ett vägnät och kontrollera kringliggande trafik. För att vara effektiv, bör kringliggande trafik inte genereras för långt bort från autonoma fordonsmodellen. OpenSCENARIO-standarden innehåller en funktion som begränsar genererad trafik inom en ellips centrerad kring fordonsmodellen. Detta examensarbete undersökte vilka tekniker som är mest effektiva och skalbara för att detektera relevanta vägar inom ellipsen att generera stokastisk trafik på. De två lösningar som studerades var: en analytisk och en numerisk som använde sig av AABB-träd-algoritmen. Utförandet började med simpla fall som successivt ökade till mer avancerade scenarion. Genom denna metodik blev varje tekniks positiva aspekter samt begränsningar belysta och jämförbara.

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