Road safety is one of the most important problems in our society. It causes hundreds of fatalities every year worldwide. A road accident may be caused by several concurrent factors. The most common are human and infrastructure. Their interaction is important too, which has been studied in-depth for years. Therefore, there is a better knowledge about the driving task. In several cases, these advances are still not included in road guidelines. Some of these advances are centered on explaining the underlying cognitive processes of the driving task. Some others are related to the analysis of drivers’ response or a better estimation of road crashes. The concept of design consistency is related to all of them. Road design consistency is the way how road alignment fits drivers’ expectancies. Hence, drivers are surprised at inconsistent roads, presenting a higher crash risk potential. This PhD presents a new, operating speed-based global consistency model. It is based on the analysis of more than 150 two-lane rural homogeneous road segments of the Valencian Region (Spain). The final consistency parameter was selected as the combination of operational parameters that best estimated the number of crashes. Several innovative auxiliary tools were developed for this process. One example is a new tool for recreating the horizontal alignment of two-lane rural roads by means of an analytic-heuristic process. A new procedure for determining road homogeneous segments was also developed, as well as some expressions to accurately determine the most adequate design speed. The consistency model can be integrated into safety performance functions in order to estimate the amount of road crashes. Finally, all innovations are combined into a new road design methodology. This methodology aims to complement the existing guidelines, providing to road safety a continuum approach and giving the engineers tools to estimate how safe are their road designs. / Camacho Torregrosa, FJ. (2015). DEVELOPMENT AND CALIBRATION OF A GLOBAL GEOMETRIC DESIGN CONSISTENCY MODEL FOR TWO-LANE RURAL HIGHWAYS, BASED ON THE USE OF CONTINUOUS OPERATING SPEED PROFILES [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/48543 / TESIS

Job insecurity in the workplace has become an increasingly important trend in organisational research. The appraisal of job insecurity by individuals plays a significant part in how reactions manifest in the experiences of workplace stressors, job satisfaction, positive and negative work attributes and social support. However, there is a lack of research regarding specific workplace stressors at work leading to certain outcomes like safety behaviour, turnover intention and mental health, especially within a South African working context. Job insecurity has also been classified as a workplace stressor. The existence of other stressors tends to increase the ultimate effect of insecurity for the individual. The attempts from organisational management to manage this phenomenon are therefore crucial in decreasing the negative effects of job insecurity and increasing the productivity of the organisation. In order to measure the job insecurity levels of employees, it is important to make use of valid and reliable job insecurity measures. An absence of empirical research on validity and reliability studies in terms of job insecurity in South African is evident. The main objectives of this research were: 1) to establish the psychometric properties of a measure of job insecurity in a selected gold mining company in South Africa; 2) to determine the influence of job insecurity and work stress (i.e. role conflict, clarity and overload) on worker safety performance and if coping could moderate this; 3) to investigate the theoretical and empirical relationships between job stressors (task completion ambiguity and task quality ambiguity), competency demands, employability perceptions, job satisfaction and turnover intention over time, and 4) to investigate if social support has a mediating effect between positive interpersonal attributes, negative interpersonal attributes, job insecurity and subsequent health. To achieve the first objective, a cross-sectional design was used (N = 566), including various business units of a South African-based gold mining company. The assessment of the psychometric properties of a measure of quantitative and qualitative job insecurity for employees was determined through construct (structural) equivalence, exploratory factor analysis and multivariate analysis of variance to calculate the comparison of the factor structure for the different cultural groups. For qualitative job insecurity, the scale shows low equivalence for the African languages group. Statistically significant differences were found between the levels of job insecurity of employees in terms of gender. The second objective, concerning the investigation into the relationship of work stress and job insecurity with unsafe behaviour at work, was achieved with across-sectional survey design (N = 771). The hypothesised model included the influence of role conflict, role ambiguity, role overload, and job insecurity on unsafe work behaviour. Coping was introduced as a moderator in this relationship. The results indicated that when employees experience work stress and job insecurity, their safety compliance is low. This relationship was also moderated by a coping strategy of Avoidance. To achieve the third objective, a longitudinal study was conducted and data was gathered by means of an electronic survey, with 771 employees participating at Time 1, and 345 participating at Time 2. Results for predicting employees’ turnover intentions, experience of task completion and quality ambiguity, external employability and job satisfaction made a direct contribution in predicting their turnover intention. No mediating role of job satisfaction between job stressors, competency demands and employability perceptions on the one hand and turnover intentions on the other hand, were found. Addressing the fourth objective in investigating the moderating role of social support between the relationship of experiencing positive interpersonal (communication with the manager and feedback), negative interpersonal experiences (powerlessness and interpersonal conflict), job insecurity (quantitative and qualitative) and health, was met with a longitudinal random sample of employees in different business units in one selected multi-national mining company based in South Africa (N = 771). Results for these employees indicated that all the proposed variables, except feedback from the manager, were statistically significantly related to health. No moderating effect for social support could be found over time, but it was shown that interpersonal conflict at work is a longitudinal predictor of employee health. By way of conclusion, the implications of the research were discussed and recommendations for managers and for future research were made. / Thesis (PhD (Industrial Psychology))--North-West University, Potchefstroom Campus, 2013.

Job insecurity in the workplace has become an increasingly important trend in organisational research. The appraisal of job insecurity by individuals plays a significant part in how reactions manifest in the experiences of workplace stressors, job satisfaction, positive and negative work attributes and social support. However, there is a lack of research regarding specific workplace stressors at work leading to certain outcomes like safety behaviour, turnover intention and mental health, especially within a South African working context. Job insecurity has also been classified as a workplace stressor. The existence of other stressors tends to increase the ultimate effect of insecurity for the individual. The attempts from organisational management to manage this phenomenon are therefore crucial in decreasing the negative effects of job insecurity and increasing the productivity of the organisation. In order to measure the job insecurity levels of employees, it is important to make use of valid and reliable job insecurity measures. An absence of empirical research on validity and reliability studies in terms of job insecurity in South African is evident. The main objectives of this research were: 1) to establish the psychometric properties of a measure of job insecurity in a selected gold mining company in South Africa; 2) to determine the influence of job insecurity and work stress (i.e. role conflict, clarity and overload) on worker safety performance and if coping could moderate this; 3) to investigate the theoretical and empirical relationships between job stressors (task completion ambiguity and task quality ambiguity), competency demands, employability perceptions, job satisfaction and turnover intention over time, and 4) to investigate if social support has a mediating effect between positive interpersonal attributes, negative interpersonal attributes, job insecurity and subsequent health. To achieve the first objective, a cross-sectional design was used (N = 566), including various business units of a South African-based gold mining company. The assessment of the psychometric properties of a measure of quantitative and qualitative job insecurity for employees was determined through construct (structural) equivalence, exploratory factor analysis and multivariate analysis of variance to calculate the comparison of the factor structure for the different cultural groups. For qualitative job insecurity, the scale shows low equivalence for the African languages group. Statistically significant differences were found between the levels of job insecurity of employees in terms of gender. The second objective, concerning the investigation into the relationship of work stress and job insecurity with unsafe behaviour at work, was achieved with across-sectional survey design (N = 771). The hypothesised model included the influence of role conflict, role ambiguity, role overload, and job insecurity on unsafe work behaviour. Coping was introduced as a moderator in this relationship. The results indicated that when employees experience work stress and job insecurity, their safety compliance is low. This relationship was also moderated by a coping strategy of Avoidance. To achieve the third objective, a longitudinal study was conducted and data was gathered by means of an electronic survey, with 771 employees participating at Time 1, and 345 participating at Time 2. Results for predicting employees’ turnover intentions, experience of task completion and quality ambiguity, external employability and job satisfaction made a direct contribution in predicting their turnover intention. No mediating role of job satisfaction between job stressors, competency demands and employability perceptions on the one hand and turnover intentions on the other hand, were found. Addressing the fourth objective in investigating the moderating role of social support between the relationship of experiencing positive interpersonal (communication with the manager and feedback), negative interpersonal experiences (powerlessness and interpersonal conflict), job insecurity (quantitative and qualitative) and health, was met with a longitudinal random sample of employees in different business units in one selected multi-national mining company based in South Africa (N = 771). Results for these employees indicated that all the proposed variables, except feedback from the manager, were statistically significantly related to health. No moderating effect for social support could be found over time, but it was shown that interpersonal conflict at work is a longitudinal predictor of employee health. By way of conclusion, the implications of the research were discussed and recommendations for managers and for future research were made. / Thesis (PhD (Industrial Psychology))--North-West University, Potchefstroom Campus, 2013.

The master thesis treats the design of control system of special purpose machine tool. The first part analyzes and compares two possible variants of control system which use either a CNC control system Sinumerik or motion control system Simotion. Only the variant with the Simotion control system is subsequently examined in detail: its hardware configuration, the selection of components and partly also the software solution. The thesis further deals with the safety of the realized control system and of the whole machine. There are described general safety requirements of machinery based on harmonized European standards and their specific application in the design of safety functions and the safety circuits of solved machine tool.

Indiana University-Purdue University Indianapolis (IUPUI) / Safety researchers have devoted extensive attention to safety performance behaviors. However, current safety performance models have yet to differentiate between safety citizenship behaviors directed towards the organization and those directed towards individuals. This might be a potential oversight, considering that citizenship behaviors targeted at different beneficiaries might be associated with different antecedents. As such, the purpose of the present study was to develop and validate a new safety performance scale. Items from existing measures formed the item pool and those tapping into the proposed dimensions were selected. Next, items were pilot tested using an online panel of 333 employees from various safety-related industries. A 4-factor structure emerged after exploratory factor analysis and the scale was further refined using reliability analysis and item response theory analysis. Finally, confirmatory factor analysis was conducted to replicate the factor structure using data from 137 employees. Theoretically related variables were correlated with the safety performance dimensions to establish the nomological network. Results supported the 4-factor structure of the new safety performance scale and construct validation hypotheses were largely supported. Implications, study limitations, and directions for future research are discussed.

Traffic safety has been considered one of the most important issues in the transportation field. With consistent efforts of transportation engineers, Federal, State and local government officials, both fatalities and fatality rates from road traffic crashes in the United States have steadily declined from 2006 to 2011.Nevertheless, fatalities from traffic crashes slightly increased in 2012 (NHTSA, 2013). We lost 33,561 lives from road traffic crashes in the year 2012, and the road traffic crashes are still one of the leading causes of deaths, according to the Centers for Disease Control and Prevention (CDC). In recent years, efforts to incorporate traffic safety into transportation planning has been made, which is termed as transportation safety planning (TSP). The Safe, Affordable, Flexible Efficient, Transportation Equity Act - A Legacy for Users (SAFETEA-LU), which is compliant with the United States Code, compels the United States Department of Transportation to consider traffic safety in the long-term transportation planning process. Although considerable macro-level studies have been conducted to facilitate the implementation of TSP, still there are critical limitations in macroscopic safety studies are required to be investigated and remedied. First, TAZ (Traffic Analysis Zone), which is most widely used in travel demand forecasting, has crucial shortcomings for macro-level safety modeling. Moreover, macro-level safety models have accuracy problem. The low prediction power of the model may be caused by crashes that occur near the boundaries of zones, high-level aggregation, and neglecting spatial autocorrelation. In this dissertation, several methodologies are proposed to alleviate these limitations in the macro-level safety research. TSAZ (Traffic Safety Analysis Zone) is developed as a new zonal system for the macroscopic safety analysis and nested structured modeling method is suggested to improve the model performance. Also, a multivariate statistical modeling method for multiple crash types is proposed in this dissertation. Besides, a novel screening methodology for integrating two levels is suggested. The integrated screening method is suggested to overcome shortcomings of zonal-level screening, since the zonal-level screening cannot take specific sites with high risks into consideration. It is expected that the integrated screening approach can provide a comprehensive perspective by balancing two aspects: macroscopic and microscopic approaches.

Traffic safety has been considered one of the most important issues in the transportation field. Crashes have caused extensive human and economic losses. With the objective of reducing crash occurrence and alleviating crash injury severity, major efforts have been dedicated to reveal the hazardous factors that affect crash occurrence. With these consistent efforts, both fatalities and fatality rates from road traffic crashes in many countries have been steadily declining over the last ten years. Nevertheless, according to the World Health Organization, the world still lost 1.24 million lives from road traffic crashes in the year of 2013. And without action, traffic crashes on the roads network are predicted to result in deaths of around 1.9 million people, and up to 50 million more people suffer non-fatal injuries annually, with many incurring a disability as a result of their injury by the year 2020. To meet the transportation needs, the use of expressways (toll roads) has risen dramatically in many countries in the past decade. In fact, freeways and expressways are considered an important part of any successful transportation system. These facilities carry the majority of daily trips on the transportation network. Although expressways offer high level of service, and are considered the safest among other types of roads, traditional toll collection systems may have both safety and operational challenges. The traditional toll plazas still experience many crashes, many of which are severe. Therefore, it becomes more important to evaluate the traffic safety impacts of using different tolling systems. The main focus of the research in this dissertation is to provide an up-to-date safety impact of using different toll collection systems, as well as providing safety guidelines for these facilities to promote safety and enhance mobility on expressways. In this study, an extensive data collection was conducted that included one hundred mainline toll plazas located on approximately 750 miles of expressways in Florida. Multiple sources of data available online maintained by Florida Department of Transportation were utilized to identify traffic, geometric and geographic characteristics of the locations as well as investigating and determination of the most complete and accurate data. Different methods of observational before-after and Cross-Sectional techniques were used to evaluate the safety effectiveness of applying different treatments on expressways. The Before-After method includes Naive Before-After, Before-After with Comparison Group, and Before-After with Empirical Bayesian. A set of Safety Performance Functions (SPFs) which predict crash frequency as a function of explanatory variables were developed at the aggregate level using crash data and the corresponding exposure and risk factors. Results of the aggregate traffic safety analysis can be used to identify the hazardous locations (hot spots) such as traditional toll plazas, and also to predict crash frequency for untreated sites in the after period in the Before-After with EB method or derive Crash Modification Factors (CMF) for the treatment using the Cross-Sectional method. This type of analysis is usually used to improve geometric characteristics and mainly focus on discovering the risk factors that are related to the total crash frequency, specific crash type, and/or different crash severity levels. Both simple SPFs (with traffic volume only as an explanatory variable) and full SPFs (with traffic volume and additional explanatory variable(s)) were used to estimate the CMFs and only CMFs with lower standard error were recommended. The results of this study proved that safety effectiveness was significantly improved across all locations that were upgraded from Traditional Mainline Toll Plazas (TMTP) to the Hybrid Mainline Toll Plazas (HMTP) system. This treatment significantly reduced total, Fatal-and-Injury (F+I), and Rear-End crashes by 47, 46 and 65 percent, respectively. Moreover, this study examined the traffic safety impact of using different designs, and diverge-and-merge areas of the HMTP. This design combines either express Open Road Tolling (ORT) lanes on the mainline and separate traditional toll collection to the side (design-1), or traditional toll collection on the mainline and separate ORT lanes to the side (design-2). It was also proven that there is a significant difference between these designs, and there is an indication that design-1 is safer and the majority of crashes occurred at diverge-and-merge areas before and after these facilities. However, design-2 could be a good temporary design at locations that have low prepaid transponder (Electronic Toll Collection (ETC)) users. In other words, it is dependent upon the percentage of the ETC users. As this percentage increases, more traffic will need to diverge and merge; thus, this design becomes riskier. In addition, the results indicated significant relationships between the crash frequency and toll plaza types, annual average daily traffic, and drivers* age. The analysis showed that the conversion from TMTP to the All-Electronic Toll Collection (AETC) system resulted in an average reduction of 77, 76, and 67 percent for total, F+I, and Property Damage Only (PDO) crashes, respectively; for rear end and Lane Change Related (LCR) crashes the average reductions were 81 and 75 percent, respectively. The conversion from HMTP to AETC system enhanced traffic safety by reducing crashes by an average of 23, 29 and 19 percent for total, F+I, and PDO crashes; also, for rear end and LCR crashes, the average reductions were 15 and 21 percent, respectively. Based on these results, the use of AETC system changed toll plazas from the highest risk sections on Expressways to be similar to regular segments. Therefore, it can be concluded that the use of AETC system was proven to be an excellent solution to several traffic operations as well as environmental and economic problems. For those agencies that cannot adopt the HMTP and the AETC systems, improving traffic safety at traditional toll plazas should take a priority. This study also evaluates the safety effectiveness of the implementation of High-Occupancy Toll lanes (HOT Lanes) as well as adding roadway lighting to expressways. The results showed that there were no significant impact of the implementation of HOT lanes on the roadway segment as a whole (HOT and Regular Lanes combined). But there was a significant difference between the regular lanes and the HOT lanes at the same roadway segment; the crash count increased at the regular lanes and decreased at the HOT lanes. It was found that the total and F+I crashes were reduced at the HOT lanes by an average of 25 and 45 percent, respectively. This may be attributable to the fact that the HOT lanes became a highway within a highway. Moreover adding roadway lighting has significantly improved traffic safety on the expressways by reducing the night crashes by approximately 35 percent. Overall, the proposed analyses of the safety effectiveness of using different toll collection systems are useful in providing expressway authorities with detailed information on where countermeasures must be implemented. This study provided for the first time an up-to-date safety impact of using different toll collection systems, also developed safety guidelines for these systems which would be useful for practitioners and roadway users.