Road trauma is recognized as a major public health problem worldwide (particularly for younger drivers), and risky driving has been identified as an important contributor to road crashes. It is often assumed that similar factors influence all risky driving behaviours, although direct and systematic examination of the differences between risky driving behaviours in terms of precipitating factors is lacking. The present thesis sought to undertake a systematic investigation of relevant factors in the prediction of four key risky driving behaviours (speeding, drink-driving, driving while fatigued, and not wearing seat belts). Four versions of a Risky Driving Questionnaire were developed to assess beliefs, personality factors and behavioural intentions, in relation to each of the four behaviours. Four versions of the Implicit Association Test were developed to assess attitudes toward each of the four behaviours, without reliance on self-report (in terms of the relative strength of pairs of associations). Data were collected from a student sample (N=215: Study 1), as well as urban (N=587) and rural (N=422) general population samples (Study 2), and regression models were examined for each of the four behaviours, with interaction terms to assess moderations involving perceived risk. Mediations involving gender were also assessed. Results indicate that different risky driving behaviours are predicted by different factors. For example, in the urban sample, speeding was predicted by driver anger and illusory invulnerability, drink driving was predicted by peer influence, driving while fatigued was predicted by the perceived benefits of not driving while fatigued, and not wearing seat belts was predicted by the (sensation seeking x illusory invulnerability) interaction. Results also suggest that different predictors of risky driving behaviours are relevant for different driver populations. For example, speeding was predicted by authority rebellion in the urban sample, and by sensation seeking in the rural sample. Observed moderations of perceived risk suggest that relationships between perceived risk and risky driving may differ for males versus females, and for low versus high sensation seekers. Findings suggest that future road safety interventions should be based on research of the determinants of individual risky driving behaviours, and in specific driver populations.

Road trauma is recognized as a major public health problem worldwide (particularly for younger drivers), and risky driving has been identified as an important contributor to road crashes. It is often assumed that similar factors influence all risky driving behaviours, although direct and systematic examination of the differences between risky driving behaviours in terms of precipitating factors is lacking. The present thesis sought to undertake a systematic investigation of relevant factors in the prediction of four key risky driving behaviours (speeding, drink-driving, driving while fatigued, and not wearing seat belts). Four versions of a Risky Driving Questionnaire were developed to assess beliefs, personality factors and behavioural intentions, in relation to each of the four behaviours. Four versions of the Implicit Association Test were developed to assess attitudes toward each of the four behaviours, without reliance on self-report (in terms of the relative strength of pairs of associations). Data were collected from a student sample (N=215: Study 1), as well as urban (N=587) and rural (N=422) general population samples (Study 2), and regression models were examined for each of the four behaviours, with interaction terms to assess moderations involving perceived risk. Mediations involving gender were also assessed. Results indicate that different risky driving behaviours are predicted by different factors. For example, in the urban sample, speeding was predicted by driver anger and illusory invulnerability, drink driving was predicted by peer influence, driving while fatigued was predicted by the perceived benefits of not driving while fatigued, and not wearing seat belts was predicted by the (sensation seeking x illusory invulnerability) interaction. Results also suggest that different predictors of risky driving behaviours are relevant for different driver populations. For example, speeding was predicted by authority rebellion in the urban sample, and by sensation seeking in the rural sample. Observed moderations of perceived risk suggest that relationships between perceived risk and risky driving may differ for males versus females, and for low versus high sensation seekers. Findings suggest that future road safety interventions should be based on research of the determinants of individual risky driving behaviours, and in specific driver populations.

Motor vehicle accidents are the leading cause of death and injury among teenagers. The crash risk is highest for young male drivers with young male passengers. The goal of this study is to find out why young males are at such high risk. One possible explanation could be the Sexual Selection Theory (Darwin, 1871), which emphasizes the competitive nature of young males that may determine their behaviour for future benefits. I tested if there was competition between males that made them take more risks while driving in the simulator. Various driving performance variables (speed, car following distance, standard deviation of the lateral position, hazard response times, number of vehicles passed) and individual differences variables (risky driving, risk perception, sensation seeking, competitiveness) were measured. Results provided little support for the effect of interpersonal competition and an opportunity for discussion arose. / AUTO21, Ontario Innovation Trust (OIT), Canadian Foundation for Innovation (CFI).

The overall aim was to elucidate the effects of vehicle passengers on young drivers. This generated two specific aims and four papers. The first aim was to investigate the crash risk for young drivers with passengers and to establish whether such accidents involve any special circumstances compared to those that occur without passengers. This goal was achieved by analysing accident and exposure data from two registers. The second objective was to analyse the group processes that develop between four young men in a vehicle and to ascertain how those interactions affect driving behaviour. Those issues were addressed by performing an observational study of twelve young men driving an instrumented vehicle in real traffic with and without passengers. The interactions between the vehicle occupants were video and audio recorded, and the driving behaviour was registered in various ways. The results show that drivers with passengers have a lower crash risk compared to those driving alone regardless of the driver’s age, although this effect is weaker for young drivers (especially males) than for other age groups. Compared to driving alone, driving with passengers for young drivers is more extensively associated with single-vehicle crashes that occur at night, on weekends, and in rural areas on roads with higher speed limits, and it leads to more severe outcomes. It has also been found that the passengers sometimes try to induce the young drivers to act in either safer or more dangerous ways, although the drivers very often resist urging and coaxing from their passengers. Cohesion is another factor that affect the driver-passenger group: a high level of cohesion, especially task cohesion, is associated with a low number of unsafe driving actions. Consequently, it seems that the presence of passengers is not enough to ensure safe driving—substantial group cohesion is also necessary for such behaviour. / Det övergripande syftet med denna avhandling var att studera passagerares effekt på unga förare, vilket genererade två delsyften och fyra delarbeten. Det första delsyftet var att undersöka olycksrisken för unga förare med passagerare och att ta reda på om dessa olyckor skedde under några speciella omständigheter. För att få svar på syftet gjordes en registerstudie där olycks- och exponeringsdata från två olika register analyserades. Det andra delsyftet var att analysera de grupprocesser som utvecklas mellan fyra unga män i en bil och att studera hur dessa interaktioner påverkar körbeteendet. Detta undersöktes med en observationsstudie där tolv unga män fick köra en instrumenterad bil i verklig trafik, både med och utan passagerare. Interaktionerna som uppstod i bilen spelades in med hjälp av videokameror och mikrofoner och körbeteendet registrerades med olika mätinstrument. Resultatet visar att förare med passagerare har en lägre olycksrisk jämfört med förare utan passagerare oavsett förarens ålder. Denna effekt är inte lika stark för unga förare (speciellt inte unga män) som den är för övriga åldersgrupper. Unga förares olyckor med passagerare är också mer vanligt förekommande under speciella omständigheter. Jämfört med olyckor utan passagerare sker de i större utsträckning under nattetid, under veckoslut, i tätbebyggt område, på vägar med hög hastighetsbegränsning, de är oftare singelolyckor och de får mer allvarliga konsekvenser. Vidare visar resultaten att passagerare ibland, på olika sätt, försöker få den unga föraren att köra på ett annat sätt än vad de gör vilket kan betyda ett säkrare eller ett mer trafikfarligt beteende. Det verkar dock som att förarna oftast står emot dessa övertalningsförsök och förolämpningar. En annan faktor som påverkar gruppen är kohesion: en hög grad av kohesion, speciellt uppgiftskohesion, visar sig leda till färre trafikfarliga körbeteenden. Med andra ord verkar det som att blotta närvaron av passagerare inte räcker för att få ett säkert körbeteende; det behövs även en betydande grad av kohesion.

This study examined what items driver education instructors felt should be included in a cultural awareness survey to assess instructors' preparedness to teach a culturally diverse student clientele. In addition, the study examined the ways driver education instructors felt a cultural awareness survey should be administered. The instrument used in the study was the Driver Education Cultural Awareness (DECA) Survey that consisted of 14 items. There were eighty-one (N = 81) participants in the study with forty-six (N = 46) from the Texas' Education Service Center, Region 4 area (Houston area) and thirty-five (N = 35) from the Texas' Education Service Center, Region 10 area (Dallas area). The findings of this study were: (1) Instructors believed that a survey instrument should include information about "preparedness to teach a culturally diverse student clientele," "men and women presented in equitable roles," and "images of teenager drivers;" and (2) Instructors did not agree on how a survey instrument should be administered.

Doctor of Philosophy / Department of Civil Engineering / Sunanda Dissanayake / Young drivers are over-represented in crashes when compared to other age group drivers. Distracted driving is one of the major causes of traffic crashes by young drivers. The objective of this study was to assess the hazards of distracted driving among teenage (15–20 year old) and young-adult (21–26 year old) drivers in Kansas. This study used five years of crash data from the Kansas Crash and Analysis Reporting System (KCARS) database from 2011 to 2015. A multinomial logit modeling was used to identify the odds that a driver with a certain type of distraction would be involved in one of the three most common crash types: rear-end, angular, and single-vehicle crashes. Furthermore, ordered logistic modeling was used to analyze the crash data to identify the odds of more severe injuries for teenage and young-adult distracted drivers and their passengers involved in crashes. Survey data was used to develop a structural equation model (SEM) to define the relationship among young drivers’ characteristics (e.g., participants’ socioeconomic and demographic status), attitudes, and behaviors associated with distracted driving and cell phone use while driving. Preliminary analysis showed that more than 12% of the total young drivers’ crashes were distraction-affected crashes. According to the multinomial logit model results, most distraction types for teenage and young-adult drivers are related to rear-end or angular collisions. However, when distracted by cell phones at night, teenage drivers had a greater probability of being involved in single-vehicle crashes. In addition, when teenage drivers drove with their peers as front-seat passengers and were distracted in/on vehicle or by other electronic devices, they were more likely to be involved in single-vehicle crashes. Young-adult drivers distracted in/on vehicle or by cell phones under different conditions such as while driving old or sport utility vehicles, on curved roads, or at intersections, they were more likely to be involved in single-vehicle or angular crashes. Whereas, when they were inattentive during the weekend, rear-end collisions were the most likely collision type. According to the results of the ordered logistic model, teenage and young-adult drivers were more likely to be severely injured in cell phone-related crashes. More specifically, female teenage drivers had a greater probability of being severely injured than male teenage drivers when they were distracted by a cell phone, inside the vehicle, or were inattentive. Young-adult drivers that were distracted on road construction work zones by a cell phone or inside the vehicle, they and their passengers had a greater likelihood of sustaining a severe injury. The SEM results revealed that teenage drivers are more prone than young-adult drivers to drive while distracted and are less likely to support the Kansas laws that ban cell phone use while driving. Also, the model results showed that young drivers who have been involved in crashes or near-crashes during the previous year are more likely to drive while distracted. These results indicate that distractions create threats to the lives of young Kansas drivers, their passengers, and other road users.

Worldwide, young drivers are involved in more road traffic collisions than any other age group (Taubman & Katz, 2012). Comprehensive driver training and various forms of pre- and- post-test road safety interventions (RSIs) are in place, but young drivers continue to be involved in more at-fault, fatal collisions than older, newly qualified drivers (e.g. Emmerson, 2008; Braitman et al, 2008; Clarke et al, 2010). The evidence base to date is mixed regarding why young drivers are at a heightened risk of collision and so this thesis aims to provide further understanding about the factors underpinning young drivers’ engagement in risky driving. An evaluation of a young driver RSI, found that young males were less likely than young females to report safer attitudes and intentions after attending the RSI. We considered that this may be due to young males’ behaviour being motivated by a desire to seek rewards (e.g. the thrill of risky driving) rather than a fear of punishment which forms the basis of traditional RSIs. Two subsequent studies were conducted to ascertain whether a heightened sensitivity to reward might underpin the risk-taking behaviour of those most at risk. We found that young males and females scoring high on reward sensitivity reported engaging in more road traffic violations and displayed slower reaction times on a driving game; suggesting that young people may have a heightened sensitivity to reward, in general, and concurrently tend to accept a higher degree of risk than other drivers. We also found that reward sensitive young drivers rated road safety messages framed in terms of financial gains as most effective, suggesting that financial incentives may be a potential route to engage young drivers in the future. The findings from another study provided insight into the precise mechanisms at play in the relationship between young drivers and their peer passengers, and the evaluation of the pilot peer-to-peer RSI showed how it might be possible to improve young drivers’ intentions to drive safely by modifying the norm that risky driving is an appropriate way to attain social prestige within a peer group. The thesis offers a significant contribution to the literature by establishing empirically the effect of reward sensitivity on young drivers’ engagement in risky driving and suggesting multiple ways to better improve young drivers’ safety in the future.

Les accidents routiers restent un problème important du secteur public de la santé au niveau international, national et régional. L’Organisation Mondiale de la Santé estime que plus d’un million de personnes meurent chaque année à cause d’un accident routier et entre 20 et 50 millions sont blessées ("Global status report on road safety: time for action," 2009). Parmi les conducteurs tués dans des accidents routiers, les jeunes conducteurs représentent au moins un quart (OECD, 2006). Les causes principales des accidents routiers, telles qu’elles sont mises en évidence dans le rapport de 2004 de l’Organisation Mondiale de la Santé (Peden et al., 2004), sont : la conduite sous l’influence de l’alcool, la vitesse, la conduite en état avancé de fatigue, l’utilisation du téléphone portable, la visibilité réduite et les facteurs appartenant à la qualité de la route. A ces causes, pour les jeunes, il faut rajouter la recherche des sensations, l’excitabilité et l’influence des pairs (A. F. Williams, 2006). L’influence des pairs représente un sujet controversé dans la littérature de spécialité à cause des résultats obtenus. Une partie des chercheurs considèrent que la présence des pairs a un effet plutôt négatif (Arnett et al., 1997; Doherty et al., 1998; Moller & Gregersen, 2008), pendant que l’autre envisage plutôt un effet positif (Delhomme, 1994; Engstrom, Gregersen, Granstrom, & Nyberg, 2008; Rueda-Domingo et al., 2004; Vollrath, Meilinger, & Krager, 2002). Cette recherche analyse l’effet des pairs sur les comportements à risque des jeunes conducteurs roumains et français en utilisant la théorie du comportement planifié, mais aussi l’effet de différents types de pressions de la part des pairs sur le comportement du jeune conducteur. Les résultats ont mis en évidence que les normes subjectives et surtout les normes subjectives de la part des amis, contribuent significativement à expliquer l’intention de réaliser des comportements à risque comme le dépassement de la vitesse et la conduite sous l’influence de l’alcool. Les analyses comparatives ont montré aussi des différences entre les deux populations. Par exemple, pour la population roumaine, les normes se retrouvent plus souvent dans les resultats des analyses que dans le cas de la population française. En plus, les jeunes conducteurs français ont un point de vue plutôt instrumental envers la voiture, en tant que pour les jeunes conducteurs roumains, la voiture représente plutôt un moyen d’impressionner les autres. Un autre résultat intéressant souligne le caractère souvent situationnel de la prise de risques chez les jeunes conducteurs accompagnés par des pairs, mais aussi les implications d’un groupe d’amis à prise de risques élevée. Pour conclure, les résultats obtenus à l’égard du rôle des normes et de l’effet de la pression des pairs sur les comportements à risque des jeunes conducteurs sont encourageants. / Road crashes remain a significant public health problem at international, national and regional level. World Health Organization estimates that more than a million persons die each year in road car crashes and that 20 to 50 million other persons are injured in those crashes ("Global status report on road safety: time for action," 2009). Among the drivers that die in car crashes almost a quarter are young drivers (OECD, 2006). The main causes of car crashes identified by WHO are driving while intoxicated, speeding, driving while tired, phone use, low visibility and poor road conditions (Peden et al., 2004). To these causes, in the case of young drivers we can add sensation seeking, excitability and peer influence (A. F. Williams, 2006). Peer influence on young drivers’ behaviour is a controversial topic in the literature due to the rather contradictory conclusions of the researches on this theme. Some researchers have found a negative effect of peer presence (Arnett et al., 1997; Doherty et al., 1998; Moller & Gregersen, 2008), while others have found a protective effect (Delhomme, 1994; Engstrom, Gregersen, Granstrom, & Nyberg, 2008; Rueda-Domingo et al., 2004; Vollrath, Meilinger, & Krager, 2002). This research analyses the effect that peers can have on young drivers’ risky behaviours by using the theory of planned behaviour approach and by looking into the effect that peer pressure type can have on the young driver. The results highlight that subjective norms and especially friend’s perceived norms contribute significantly to explaining young drivers’ intention to speed or to drive while intoxicated. The comparative analysis showed some interesting differences among the two populations. For example, for the Romanian drivers norms play a much more important role in explaining risky driving behaviours that for the French population. Also, young French drivers perceive the car as having rather an instrumental role while Romanian drivers see it more like a way to impress. Another interesting result emphasizes on the situational character of young drivers risk taking but also on the implications that risk taking peers might have. Finally, the results obtained regarding the role of norms and the effects of peer pressure on young drivers’ behaviour are rather encouraging.

Doctor of Philosophy / Department of Civil Engineering / Sunanda Dissanayake / Young drivers have elevated motor vehicle crash rates compared to other drivers. This dissertation investigated characteristics, contributory causes, and factors which increase the injury severity of young driver crashes in Kansas by comparing them with more experienced drivers. Crash data were obtained from the Kansas Department of Transportation. Young drivers were divided into two groups: 15-19 years (teen) and 20-24 years (young adult) for a detailed investigation. Using data from 2006 to 2009, frequencies, percentages, and crash rates were calculated for each characteristic and contributory cause. Contingency table analysis and odds ratios (OR) analysis were carried out to identify overly represented factors of young-driver crashes compared to experienced drivers. Young drivers were more likely to be involved in crashes due to failure to yield-right-of way, disregarding traffic signs/signals, turning, or lane changing, compared to experienced drivers. Ordered logistic regression models were developed to identify severity affecting factors in young driver crashes. According to model results, factors that decreased injury severity of the driver were seat belt use, driving at low speeds, driving newer vehicles, and driving with an adult passenger. The models also showed that alcohol involvement, driving on high-posted-speed-limit roadways, ejection at the time of crash, and trapping at the time of crash can increase young drivers’ injury severity. Based on identified critical factors, countermeasure ideas were suggested to improve the safety of young drivers. It is important for teen drivers and parents/guardians to gain better understanding about these critical factors that are helpful in preventing crashes and minimizing driving risk. Parents/guardians can consider high-risk conditions such as driving during dark, during weekends, on rural roads, on wet road surfaces, and on roadways with high speed limits, for planning teen driving. Protective devices, crash-worthy cars, and safer road infrastructures, such as rumble strips, and forgiving roadsides, will particularly reduce young drivers’ risk. Predictable traffic situations and low complexity resulting from improved road infrastructure are beneficial for young drivers. The effectiveness of Kansas Graduated Driver Licensing (GDL) system needs to be investigated in the future.

Merging from on-ramps to mainline traffic is one of the most challenging driving maneuvers on freeways. The challenges are further heightened for older drivers, as they are known to have longer perception-reaction times, larger acceptance gaps, and slower acceleration rates. In this research, VISSIM, a microscopic traffic simulation software, was used to evaluate the influence of the aging drivers on the operations of a typical diamond interchange. First, drivers were recorded on video cameras as they negotiated joining the mainline traffic from an on-ramp acceleration lane at two sites along I-75 in Southwest Florida. Several measures of effectiveness were collected including speeds, gaps, and location of entry to the mainline lanes. This information was used as either model input or for verification purposes. Two VISSIM models were developed for each site – one for the existing conditions and verification, and another for a sensitivity analysis, varying the percentage of older drivers and Level of Service (from A to E), to determine their influence on ramp operational characteristics. According to the results, there was a significant difference in driving behavior between older, middle-aged, and younger drivers, based on the measures of effectiveness analyzed in this study. Additionally, as the level of service and percentage of older adult motorists increased, longer queues were observed with slower speeds on the acceleration lanes and the right-most travel lane of the mainline traffic.