Growth trends in vehicle transportation for the year 1989 showed that truck travel has increased from 400 billion vehicle miles of travel to 600 billion vehicle miles from 1980 to 1989, a staggering 50% increase. If this trend continues, then truck travel will reach 800 billion vehicle miles by the end of the year 2000. This increase in truck travel poses operational and safety problems for both passenger vehicles and trucks. To improve the existing highway facilities for trucks as well as to determine the design standards for new truck facilities, an understanding of the relationship between truck accidents and highway geometry is required. A number of models have been developed in the past but none of them consider all of the geometric features of the highway which are crucial for truck travel and the causation of truck accidents. The objectives of this study were to identify the roadway variables that affect truck accidents and to develop mathematical models which would determine truck involvement rates, per mile, per year. Data from the Highway Safety Information System (HSIS) was used in this analysis. The HSIS is a new data base developed by FHWA which contains accident, roadway and traffic data from five States. Models for truck accidents on Interstates, 2 lane rural roads, and for over turning accidents on Interstates were developed. The models indicate that truck accidents are primarily affected by horizontal curvature and vertical gradient albeit their values are different for Interstates and 2 lane rural roads. The number of truck accidents decreases on 2 lane rural roads as the shoulder width increases, and the model indicates that gradient has no effect on truck accidents on these roads and this, may be due to the inadequacy of the data. The Interstate model indicates that the higher the degree of curvature and the percentage of gradient, the greater the number of truck accident, as well as overturning truck accident involvement rates. / Master of Science

The goal of this experiment was to determine what if any effect two different types of warnings have the brake reaction time of distracted commercial motor vehicle operators. The warning conditions were: No Warning, Auditory Tire Skid Warning, and One Second Brake Pulse Warning. Each participant was distracted via a distracter task during the experiment. As the participants were distracted, an obstacle was launched out into their forward path. Each participant received his/her appropriate warning, according to what condition they were placed, when the obstacle entered their headway. It was determined that the Auditory Tire Skid Warning aided in decreasing the movement times, while the One Second Brake Pulse Warning aided in decreasing the number of collisions with the barrels and speed at contact with the barrels. / Master of Science

Twenty-four subjects, each having a valid Virginia driver's license (males and females of ages from 20 to 73), read aloud words presented on two displays while driving a simulated vehicle in night-time conditions. The words, emulating printed legends found on automobile instrument panels, were presented in different hues (eight levels), brightnesses (two levels), character sizes (four levels), and word complexities (two levels). The brightness levels had been subjectively determined in a preliminary experiment by subjects representative of the older and younger segments of the driver population. Each of two groups of drivers determined one brightness level that was subjectively equal among the eight hues. For each word presented, six reading and driving performance measures were taken. Also, subjective attractiveness, subjective comfort, and subjective ease of readability of each hue by brightness treatment combination, were measured. Globally, the results tend to indicate that color of illumination per se had a reliable effect on subjective preferences but a negligible effect on reading and driving performance. Brightness had an impact on performance only with the smaller character sizes. For the larger sizes, brightness level as selected by the subjects (in the preliminary experiment) had a negligible effect on performance. Character size had marked effects on both performance and subjective preferences. The two smaller character sizes tested yielded significant performance decrements for older drivers while the two larger sizes yielded best performance and were better accepted by all subjects. Word complexity did show a significant effect on glance time at the displays with all character sizes. The results of the experiment were transformed into a set of guidelines for use in design of automobile instrument panels. A number of recommendations for future research are also included. / Ph. D.

Coastal flooding has been increasing in frequency and severity across the US East Coast, adversely impacting the human population. Preferred adaptation strategies, such as protection and accommodation, may prove insufficient under current climate change scenarios and projected future sea level rise, prompting the coastal population to consider relocation as a more efficient disaster risk reduction strategy. This study focuses on the flood-prone urban areas along the US East Coast where residents are more willing to relocate due to coastal flooding. Using the survey data, it evaluates the flood experiences, considerations toward relocation, and preferences for relocation destinations. The extent of top concerns influencing respondents' willingness to relocate, such as crime rate, buyout programs, access to critical services and amenities, and availability of comparable housing, were further explored as indirect relocation drivers. Four study locations with heightened relocation potential were identified across urban areas on the US East Coast. Relocation drivers such as crime and limited access to services and amenities are not significantly present in these study locations. However, the absence of buyout programs and affordable housing options in similar communities leaves low-income households trapped in high-risk zones, exacerbating socioeconomic disparities, and increasing the disproportionate risk faced by marginalized populations. The findings have important implications for policymakers, urban planners, and stakeholders involved in climate adaptation and disaster risk reduction efforts. They highlight the need for targeted interventions to address socioeconomic vulnerabilities, promote equitable access to housing, and enhance the resilience of communities facing coastal hazards. / Master of Science / Coastal flooding is increasing in both frequency and severity along the US East Coast, significantly impacting local populations. Traditional adaptation strategies, such as building protective structures and making accommodations, may not be sufficient under current climate change scenarios and projected sea level rise. Consequently, some coastal residents are considering relocation as a more effective strategy for reducing disaster risk. This study focuses on flood-prone urban areas along the US East Coast, where residents are more inclined to relocate due to coastal flooding. Using survey data, it assesses their flood experiences, considerations towards relocation, and preferred relocation destinations. The study also examines indirect factors influencing the willingness to relocate, such as concerns about crime rates, buyout programs, access to essential services and amenities, and the availability of comparable housing. The research identifies four study locations of urban areas with a high potential for relocation. In these study locations, issues such as crime and limited access to services and amenities are less significant. However, the absence of buyout programs and affordable housing options in similar communities traps low-income households in high-risk zones, exacerbating socioeconomic disparities and increasing the disproportionate risk faced by marginalized populations. These findings have significant implications for policymakers, urban planners, and stakeholders involved in climate adaptation and disaster risk reduction. They highlight the need for targeted interventions to address socioeconomic vulnerabilities, promote equitable access to housing, and enhance the resilience of communities facing coastal hazards.

Innovation is a popular topic that receives significant attention from both organizations and academics. This attention includes scholars, executives, public entities, and private organizations in the construction and infrastructure fields. Scholars have examined innovation in both construction and public-private partnerships (P3s). Despite this work, gaps remain — particularly regarding the impact of project-level factors on technical innovation in P3s. Hence, this dissertation contributes to the areas of infrastructure innovation and P3s using a three pronged approach. First, exploration of the literature identified 348 factors that drive or inhibit innovation in infrastructure projects. These factors were synthesized into 33 aggregate factors such as client, integration, and risk. Subsequently, case interviews with practitioners revealed 110 factors that influence innovation in P3 projects; these were further grouped into six main categories. Literature and practitioner perspectives were strongly aligned around four predominant factors influencing innovation in P3 projects: i) risk, ii) client, iii) procurement, and iv) project type. Second, a framework to identify and classify project level innovation was derived and tested using deviations from project baselines submitted as alternative technical concepts (ATCs) in four infrastructure project procurements. The developed framework provides the infrastructure and construction community with a replicable approach to assess technical enhancements in projects to determine whether they are innovative or not and if so the type of innovation. Application of the framework classified only 7 of 53 ATCs from the four projects as innovative. However, the remainder added significant value through cost savings, improved safety or operational efficiency. Lastly, a case study of six contemporary US highway P3 projects: i) Elizabeth River Tunnels in Virginia; ii) East End Crossing in Indiana; iii) North Tarrant Expressway segments 3AandB in Texas; iv) I-4 Ultimate Improvement in Florida; v) I-77 HOT Lanes in North Carolina; and vi) SH 288 Toll Lanes in Texas was conducted to determine the types of innovation found and to assess the influence of key project characteristics on P3 technical innovation. Technical enhancements proposed by concessionaires were assessed using project documentation and semi-structured interviews with 23 experienced public and private sector project participants. Innovations were uncovered, albeit limited. Procurement, project type, and payment mechanism (demand risk/traffic risk) were the key project characteristics influencing innovation. Further, these same characteristics promoted added-value in the form of increased safety, reduced project durations, and decreased project costs. Together, the three studies advance our understanding of the effect of project attributes on technical innovation and value creation in infrastructure public-private arrangements. / PHD / Governments around the world are using public-private partnerships (P3s) to provide needed infrastructure. They often claim that the involvement of the private sector in the delivery of infrastructure will generate various benefits, particularly innovation. However, public agencies and private infrastructure developers provide limited evidence of innovation outcomes. While academic scholars have explored the topic, the studies are limited and have generated alternative results. This dissertation contributes to the areas of infrastructure innovation and P3s with three independent but interrelated studies. First, the exploration of the literature and the perspectives of 23 experienced project participants identified four predominant factors that influence the occurrence of innovation in P3 projects: i) risk, ii) client, iii) procurement, and iv) project type. Second, a framework to identify and classify project level technical innovations in a replicable and transparent manner was developed and tested. Lastly, a multi-case study approach was adopted to determine the types of innovation found and to assess the influence of key project characteristics on P3 project technical innovation. Project documentation was assessed and interviews were conducted with public and private participants in six contemporary US highway P3 projects. Technical innovation was found within the cases, albeit limited. Demand risk and involving the private partner early were two of the most influential project characteristics on technical innovation. Further, these two characteristics promoted added-value technical enhancements through increased safety, reduced project durations, and decreased project costs.

Deindividuation is a psychological phenomenon that occurs when a given environment reduces the "individuality" or identifiability of a person. These environments may cause a psychological reduction in self-consciousness, potentially leading to violations of sociocultural norms (Festinger, Pepitone, & Newcomb, 1952; Singer, Brush, & Lublin, 1965). The present research sought to empirically test deindividuation theory among automobile drivers utilizing the anonymizing factor of observation. Participants (N = 31) used a driving simulator and were either in the observed condition or an unobserved condition. Analysis of driving data did not reveal significant results, however self-report data had some interesting trends. Though limited in scope, this research begins to shed light on deindividuation of drivers and may provide a foundation for future research.

Ph. D.

The aging process is often accompanied by declines in one or more physical, vision, and/or cognitive abilities that may impact driving safety. As older drivers become more self-aware of these functional deficits, they have the tendency to engage in self-regulation practices, such as less driving and avoiding challenging driving situations. This tendency may gradually evolve to give up driving altogether. Advanced Driver Assistance Systems (ADAS) holds promise for improving older drivers' safety on the road as well as maintaining their mobility by compensating for declines in visual, cognitive, and physical capabilities. However, the perception of these technologies can influence the realization of these expected benefits. The overarching goal of this research is to understand and enhance the safety and mobility of older adults by examining the impact of ADAS. The dissertation addresses this goal by investigating mobility, perception, safety measures, and safety. Study 1 employed structure equation modeling (SEM) on the data from the Second Strategic Highway Research Program (SHRP 2) on driving habits with respect to age, gender, living status, health, and functioning capabilities. The results illustrate that older drivers' health is a reliable predictor of driving exposure, and cognitive and physical declines are predictive of their intention to reduce exposure and actual driving in challenging situations. These findings highlight that the aging population requires support for their mobility and likely road safety given their age-related impairments. Study 2 employed structure topic modeling on a focus group of older adults driving vehicles equipped with ADAS for six weeks was conducted to reveal five key issues to older drivers (in the order of prevalence): (1) safety, (2) confidence concerning ADAS, (3) ADAS functionality, (4) user interface/usability, and (5) non-ADAS related features. The findings point to a need for holistic ADAS design that not only must consider safety concerns but also user interfaces accommodating older adults' preferences and limitations as well as in-depth training programs to operate ADAS given the technology limitations. Study 3 employed correlation analysis and logistic regression on SHRP 2 data to reveal that the longitudinal deceleration events at greater than 0.60g and lateral acceleration events at greater than 0.40g appear most associated with older adults' driving risk and are predictive of near future crash and near-crashes (CNCs) occurrence and high-risk older drivers with acceptable accuracy. These findings indicate that high g-force events can be used to assess risk for older drivers, and the selection of thresholds should consider the characteristics of drivers. Study 4 compared high g-force events between two naturalistic driving studies to reveal that drivers who drove vehicles equipped with ADAS had lower longitudinal declaration rates, indicating the benefits of ADAS presence on older drivers' safety. When lane keeping assist (LKA) was engaged, lower high longitudinal deceleration was observed than when LKA was not engaged, indicating that older drivers tended to apply less aggressive braking when using LKA. Over several weeks of exposure to vehicles with ADAS presence, older drivers showed decreasing longitudinal deceleration but increasing lateral acceleration events. In other words, the potential of ADAS for positive safety-related impacts exists but some refinement in the design to reduce lateral events might be necessary. / Doctor of Philosophy / As people grow older, they may experience declines in their physical, vision, and cognitive abilities, which can affect their ability to drive safely. Many older drivers become more aware of these limitations and tend to drive less or avoid challenging situations, gradually some eventually stop driving altogether. Advanced Driver Assistance Systems (ADAS) hold the potential to enhance the safety and mobility of older drivers by compensating for these declines in vision, cognition, and physical capabilities. However, the way older adults perceive and accept these technologies can influence their effectiveness. This research focuses on understanding and improving the safety and mobility of older adults by examining the impact of ADAS on them through four studies. These studies fill gaps in research and provide insights into the potential of ADAS to enhance both the safety and mobility of older drivers. This research is vital for improving the quality of life for older adults and making our roads safer for all.

Thesis (MEng)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Driving is a complex task that requires both the physical ability to drive a vehicle and the cognitive ability to do so safely. The ability to correctly integrate and apply information from the driving environment is essential for safe driving. In South Africa approximately 33 people per 100 000 population are killed annually in road accidents. Recent mortality data from South Africa has indicated that the age group 15 to 19 years old are the age group most likely to be involved in fatal vehicle crashes. Novice driver behaviour has been confirmed as problematic across the globe and extensive research into novice driver behaviour has been conducted to understand and ultimately to curb novice driver deaths. Very little is known about South African novice drivers. This lack of knowledge makes it difficult to plan for training, education or preparing young South African novice drivers for the challenges they are likely to face on the road. This study is a first stepping stone to understand this problem. This study utilises naturalistic driving studies as a method to explore differences between novice and experienced driver behaviour at a few preselected location types. Since 2005 naturalistic driving studies (NDS) have been employed extensively in the rest of the world and this study is South Africa’s first small attempt to employ this methodology and apply it to specifically novice driver behaviour. This thesis therefore not only explores novice driver behaviour in the context of South Africa, but also provides an overview of how the ND methodology can be developed for use in South Africa. The document provides an overview of both novice driver behaviour and naturalistic driving study methodologies from abroad. Where available, reference to South African research and reports are made. The literature review considers demographic, developmental and personality factors that could potentially (and have internationally been proven to) influence novice driver behaviour in the context of society, family and physical environments. Popular theories that have been applied to novice driver behaviour are reviewed. These theories include the Theory of Planned Behaviour, Social Learning Theory and the Theory of Intent. On the methodology side, the technology, its application as well as challenges and successes of the ND methodology are reviewed. The research process is described in terms of the participants and their risk attitudes to road traffic safety prior and after the study. The research process also details the specifications of the technology used, the data collected and the associated processes to make the data manageable. The research process took a number of unexpected turns which included the development of a coding scheme for the image material. Initially it was thought that this coding scheme should be predefined. However once the coding process commenced it was clear that in-vivo coding was necessary for inclusion of all elements of the environment and the behaviour. These elements differed from video to video and participant to participant. Grounded theory was introduced in an attempt to explain the novice behaviour. Although the data analysed was not extensive enough to substantiate the use of grounded theory it is considered useful in operationalizing this coding scheme in future. In addition to learning how to work with the data collection systems and how to integrate different types of quantitative and qualitative data in different formats, it also became clear that a strategy for managing large databases should be considered. This was an unexpected spin-off and is currently being investigated. The findings of the study showed that certain behaviours (such as the left scanning of a driving environment) were neglected not only by novice drivers but also by experienced drivers. Further investigations could include research into understanding this phenomenon. The preselected site types included stop streets, traffic lights, traffic circles and intersections. Traffic lights and intersections in particular have in recent years been highlighted as hazardous locations in Pretoria, where the study took place. Differences in behaviours were highlighted for intersections but not for traffic lights, stop streets or traffic circles. However the difference in the proportion of time that novice and experienced drivers took to scan their environments around these preselected hazardous locations differed significantly. Experienced drivers were much more thorough than their novice counterparts. This study was aimed at investigating the differences between novice and experienced drivers and aimed to develop recommendations that could potentially have implications for changing the driver training and education milieu in SA. However, the sample size (both participants and material selected for analysis) was too small to make meaningful recommendations towards change in this industry. It did however show clear differences between novice and experienced drivers, even in South Africa, and that this research needs to be expanded. The potential of this research for South Africa is enormous and could quite possibly, in future, change the way in which South Africans drive.

Thesis (MEng)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: Every year, more than 1.24 million traffic related deaths are registered globally with the highest fatality rates in middle- and low income countries. Minibus taxis represent the most dominant mode of public transportation associated with road traffic crashes and injuries in most African countries. From a safety perspective, aggressive driving behaviour is one of the main causes of road traffic crashes. This study examined the nature and the frequency of the most common types of the minibus taxis drivers’ on-road aggressive behaviour as well as the corresponding response behaviour of drivers of other vehicles to those behaviours. The research was done through video observations in Cape Town, South Africa. Through questionnaires, this study also explored the effect of driver age and gender of minibus taxi drivers on the on-road aggressive behaviour. The effect of age and gender of drivers frustrated by minibus taxi drivers’ aggressive on-road behaviours on levels of anger aroused as well as on the response behaviours reported was investigated from within the framework of a frustration and aggression model of aggressive driving. In a total of 7,266 minibus taxis observed from three different sites, 943 aggressive driving behaviours noted were divided into three categories: traffic obstructions (stopping in the road or outside bus stops), disregarding traffic signs and signals (red light running and violating stop lines), and improper passing behaviours (cutting in too close, overtaking on road shoulder or on yellow lane, crossing solid lines to pass vehicles in the next lane, inappropriate lane utilisation). Observations were coded based on pre-determined evaluation indices. The more frequent response manoeuvres by drivers behind aggressive minibus taxis were swerving to the next lanes, accelerating to refuse gaps for minibus taxis, running behind minibus taxi red light runners, and hooting. The results from the questionnaire survey revealed that driver age and gender affected both the minibus taxi drivers’ on-road aggressive behaviours and the response behaviours reported by other drivers. Respondents reported that younger minibus taxi drivers exhibit more on-road aggressive behaviour than old minibus taxi drivers. Male and younger drivers frustrated by minibus taxis’ on-road aggressive behaviours reported riskier and more severe forms of reactions than frustrated female and older drivers. The responses of drivers of other vehicles to the minibus taxi drivers’ on-road aggressive behaviours have parallels with the responses of individuals to social bullying or victimisation, as researched and explained in social-psychological theory. More work is needed to explore this relationship but it is possible that the responses of drivers of other vehicles to the minibus taxi drivers’ aggressive behaviours could be explained by these theories. / AFRIKAANSE OPSOMMING: Elke jaar word meer as 1.240.000 verkeer verwante sterftes met die hoogste sterftekoerse in die middel- en lae-inkomste lande geregistreer. Minibus-taxi's verteenwoordig die mees dominante vorm van openbare vervoer wat verband hou met verkeer ongelukke en beserings in die meeste van die Afrika- lande. Wat veiligheid betref, is aggressiewe bestuursgedrag een van die belangrikste oorsake van die verkeers-ongelukke. Hierdie studie ondersoek die aard en die frekwensie van die mees algemene vorme van minibus taxi-bestuurders se aggressiewe padgedrag sowel as die reaksies van bestuurders van ander voertuie op dié gedrag. Die navorsing is deur middel van video waarneming in Kaapstad uitgevoer. Hierdie studie het ook die effek van die minibus taxibestuurders se ouderdom en geslag op aggressiewe padgedrag met vraelyste ondersoek. Die uitwerking van aggressiewe bestuurgedrag op die vlakke van woede wat deur ander bestuurders ervaar word, sowel as op hul reaksies is vanuit die raamwerk van 'n frustrasie en aggressie model van aggressiewe bestuur ondersoek. In totaal van 7266 minibus-taxi's is waargeneem op drie verskillende plekke. Die 943 voorvalle van aggressiewe ry-gedrag is in drie kategorieë verdeel naamlik verkeer obstruksies, verontagsaming van verkeerstekens en -seine, en onbehoorlike gedrag. Gedrag is gekodeer deur van voorafbepaalde evaluering-sindekse gebruik te maat. Hierdie gedrag het ingesluit belemmer in a van verkeer, insny voor ander verkeer, kruising van soliede lyne, onvanpaste laangebruik, verbysteek op pad-skouers of op die geellyne, verontagsaming van rooi verkeersseine, en die oortreding van stoplyne. Die mees waargenome reaksies deur voertuie agter aggressiewe minibus-taxi's is wegswenk na die volgende lane, versnelling om gapings vir minibus-taxi's te weier, naloop agter taxi wat deur verkeerseine ry, en die gebruik van die toeter. Die resultate van die vraelysopnames het getoon dat die bestuurder se ouderdom en geslag beide die taxi- bestuurders se aggressiewe padgedrag en die reaksie-gedrag daarop bepaal. Resondente het aangedui dat jonger minibus-taxi-bestuurders meer aggressiewe padgedrag as ouer minibus taxi-bestuurders toon. Die response van die ander bestuurders op taxibestuurders se aggressiewe padgedrag het ooreenkomste met die reaksies van individue tot sosiale boeliegedrag of viktimisering , soos nagevors en verduidelik in sosiaal-sielkundige teorie. Verdere werk is nodig om hierdie verhouding te verken, aangesien dit moontlik is dat die reaksies van bestuurders van ander voertuie op minibustaxi- bestuurders se aggressiewe padgedrag deur hierdie teorieë verklaar kan word.