This study examined the variability in the observed relationship between safety climate and injuries in the extant literature by meta-analytically examining possible moderators of the safety climate-injury relationship at both the individual and group levels of analysis. Hypotheses were posited regarding the effects of six moderators: study design (i.e., retrospective or prospective), the time frame for gathering injury data, the degree of content contamination and deficiency in safety climate measures, the source of injury data (i.e., archival or self-report), and the operationalization of injury severity. Results revealed that the safety climate-injury relationship is stronger at the group level (? = -.23) than at the individual level of analysis (? = -.18). Meaningful moderators included the time frame between the measurement of safety climate and injuries for prospective group-level studies, safety climate content contamination for group-level studies, and safety climate content deficiency for individual-level studies. Longer time frames for gathering injury data and safety climate content deficiency were found to decrease effect sizes while content contamination was associated with stronger effect sizes. Methodological recommendations are proposed for future research of the safety climate-injury relationship including prospective longitudinal study designs with data collected and analyzed at the group-level of analysis and injuries operationalized at a greater level of severity.

Lean construction borrows concepts from lean manufacturing and Toyota Production System in order to eliminate waste and add value to the construction process. Manufacturing processes utilizing lean principles have matured and developed a clear understanding of the relation between lean and safety. Because lean in construction is a relatively new phenomenon, there is not a completely developed understanding of how lean practices affect safety in construction. The Lean Construction Institute and the Academic Forum for Lean Construction has recently targeted this area for focused research. Since all safety incidents imply waste in time and resources, lean and safety have a common ground in the minimization of waste. This thesis researches the common ground of lean and safety in waste minimization and proposes a framework for understanding their relationship. This thesis also critically analyzes lean and safety principles to form an insight to the relationship between lean theories as well as practices and safety issues reported in construction literature. Further, literature also revealed the safety strategies and checklists that companies typically incorporate in their program. A comparative analysis of lean and safety is employed to understand their relations in a better way. This framework establishes that lean and safety have a strong relationship in the context of construction. Future work is needed to show that lean practices indeed strongly affect safety by reducing the number of incidents.

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Inherent safety has been recognized as a design approach useful to remove or reduce hazards at the source instead of controlling them with add-on protective barriers. However, inherent safety is based on qualitative principles that cannot easily be evaluated and analyzed, and this is one of the major difficulties for the systematic application and quantification of inherent safety in plant design. The present research introduces the use of fuzzy logic for the measurement of inherent safety by proposing a hierarchical fuzzy model. This dissertation establishes a novel conceptual framework for the analysis of inherent safety and proposes a methodology that addresses several of the limitations of the methodologies available for current inherent safety analysis. This research proposes a methodology based on a hierarchical fuzzy model that analyzes the interaction of variables relevant for inherent safety and process safety in general. The use of fuzzy logic is helpful for modeling uncertainty and subjectivities implied in evaluation of certain variables and it is helpful for combining quantitative data with qualitative information. Fuzzy logic offers the advantage of being able to model numerical and heuristic expert knowledge by using fuzzy IF-THEN rules. Safety is traditionally considered a subjective issue because of the high uncertainty associated with its significant descriptors and parameters; however, this research recognizes that rather than subjective, "safety" is a vague problem. Vagueness derives from the fact that it is not possible to define sharp boundaries between safe and unsafe states; therefore the problem is a "matter of degree". The proposed method is computer-based and process simulator-oriented in order to reduce the time and expertise required for the analysis. It is expected that in the future, by linking the present approach to a process simulator, process engineers can develop safety analysis during the early stages of the design in a rapid and systematic way. Another important aspect of inherent safety, rarely addressed, is transportation of chemical substances; this dissertation includes the analysis of transportation hazard by truck using a fuzzy logic-based approach.

Enteric viruses are responsible for a significant amount of foodborne disease in the United States. Foodborne disease associated with enteric viruses has been increasing within the last few years due to technological advances and raised awareness. Salads and salad crops are the principal vector for transmission of enteric viruses. The objective of this study was to determine if viruses are able to attach non-specifically to the surface of lettuce and to determine the forces responsible for non-specific viral adsorption to lettuce. Additionally, the impact of the microbial flora on viral persistence was studied to determine the effect on viruses. The four viruses studied were echovirus 11, feline calicivirus, MS2 and φX174. The viruses were chosen based on their varying isoelectric points and similar physicochemical attributes. The isoelectric point was not the main factor determining virus attachment to lettuce. Viruses had varying attachment efficiencies, with echovirus 11 having the highest affinity to lettuce and φX174 the least. Viral adsorption to lettuce was mediated by electrostatic forces due to the removal of virus adsorption at pH 7 and 8 with the addition of 1 M NaCl to the buffer solutions. Microcosm studies indicated that the microbial flora did not have a negative impact on virus survival. The bacteriophages had the highest survival rate. Virus survival in the microcosm studies was not indicative of virus survival on the surface of the lettuce. The animal viruses exhibited survival rates greater than or equal to the survival of bacteriophages at 4° C, but at room temperature viable animal viruses rapidly declined compared to the bacteriophages. Additional studies also indicated that the microbial flora was not able to degrade the viruses for aerobic microbial growth. Overall, these results indicate that viruses are able to attach to the surface of lettuce, providing a possible explanation for the high incidence of virus associated disease involving salads and fresh produce. More importantly the use of surrogates for virus studies involving fresh produce must be re-evaluated, because of the lack of correlation between animal viruses and bacteriophages. Appropriate viral surrogates, if used, have to be carefully chosen based on viral physicochemical properties as well as the infectious route of the virus.

Small and very small slaughterhouses generally spray lactic acid for carcass decontamination utilizing a hand held sprayer. Even though this tool represents a very small investment, it may present important disadvantages such as uneven delivery of the spray over the carcass surface. If the decontamination treatment is not applied properly, the untreated areas of the carcass will still have high bacterial loads present and could be a source for recontamination of the areas that have been treated. A sanitizer spraying system (sanitizing halo system) was designed and assembled. The sanitizing halo system was tested at the Rosenthal Meat Science and Technology Center, Texas A&M University. Thirteen carcasses were split in halves. Thirteen halves were sampled and used as control after knife trimming and water wash; then they were sprayed with 2% L-Lactic at 55°C with the sanitizing halo system. The other 13 halves were sprayed by the RMSTC employees utilizing a hand held sprayer. Counts of aerobic and mesophilic bacteria obtained from carcasses sprayed with the sanitizing halo system and the hand held sprayer were both significantly lower than the control counts. In addition, coliforms counts were below the detectable limit for the sanitizing halo system and the hand held sprayer. After testing, the sanitizing halo system was installed at two small commercial slaughter plants processing beef and pork carcasses. At each slaughter plant, 24 carcass halves were treated with 2% L-Lactic at 55°C using the sanitizing halo system, and the other 24 halves were used as control. Mesophilic bacteria populations were reduced in beef and pork carcasses by 2.9 and 1.9 log cycles, respectively, after the lactic acid treatment. Also E. coli counts were significantly lower in the three regions sampled after application of the 2% L-Lactic acid with the sanitizing halo system. From the data collected during this study, we recommend the sanitizing halo system as a tool to reduce the bacterial loads on the surface of beef and pork carcasses. The use of this system should help small and very small slaughterhouses to improve food safety performance while providing cost-efficiency, simplicity, and convenience.

The growth of vehicle travel in the United States has accelerated wear on the interstate highway system leading to frequent pavement repair and rehabilitation projects. The presence of work zones not only causes traffic congestion and backup but also increases the crash risk. Therefore, the FHWA (Federal Highway Administration) has allotted a significant amount of funds to improve work zone traffic safety and operations. This thesis compares truck and automobile crash characteristics in work zones with those of non-work zones and thus identifies engineering countermeasures to improve work zone truck safety. The researcher used a contingency analysis approach in this study. First, he categorized the North Carolina crash data using different variables. Once categorized, the Breslow-Day test is used to compare the odds of truck and automobile crashes between work zones and non-work zones. Overall, the researcher did not find a significant difference between odds of truck and automobile crashes compared to previous studies. The researcher believes that the difference in results between the present study and the previous studies could either be due to differences in the approach used or better truck management techniques employed by the North Carolina DOT (Department of Transportation). The researcher also identified that the maintenance projects performed during the day had a significantly higher odds of truck crashes relative to that of automobiles in work zones compared to control sections when workers were present, either with a lane closure or without a lane closure. The researcher believes that the results from the day maintenance projects and its subcategories are the key findings of this study. Therefore, these key findings are used to identify the possible reasons and countermeasures for any disproportionate change in truck to automobile crashes. The identified list of countermeasures includes the use of law enforcement, a smart work zone system, a dynamic late merge system, CMS (Changeable Message Signs), speed display signs, and a CB (Citizen Band) Wizard. These countermeasures were checked for cost effectiveness using a benefit cost (B/C) analysis. The researcher found that law enforcement, smart work zones with costs lower than or equal to half a million dollars, CMS, speed display signs, and the CB Wizard have B/C ratios greater than one and seem to be worthwhile for deployment in work zones. Smart work zones with significantly higher costs of 2.5 million dollars, for example, could be deployed using a more detailed analysis of work zone characteristics. Finally, dynamic late merge system could be used if the site conditions indicate a crash reduction potential of at least 10 - 15 percent.

In accordance with the federally mandated Highway Safety Improvement Program (HSIP), every state is required to "develop and implement, on a continuous basis, a highway safety improvement program which has the overall objective of reducing the number and severity of crashes and decreasing the potential for crashes on all highways" (FHWA, 1979). The federal government via the HSIP provides a significant amount of funding that allows every state to improve the safety of their highway network. With such large amounts of federal funds involved, it becomes essential that state transportation agencies take appropriate measures to utilize these funds in the most cost effective manner. As part of this program, the Texas Department of Transportation (TxDOT) uses a formula known as the "Safety Improvement Index" (SII) for identification, ranking and selection of eligible projects. The SII is in essence used to rank potential projects by giving priority to projects that have a higher benefit-cost (B/C) ratio. Since the SII has not been updated within the last two decades, there is a need to determine whether the current formulation needs to be revised or updated. This concern has been reported in the literature. The objective of this thesis is to evaluate the SII in its current functional form and its usefulness to rank and prioritize projects for safety improvement. The evaluation procedure proposed in this thesis uses sensitivity analyses to study the effects of different input variables on the SII. The sensitivity analysis is performed with respect to five critical variables chosen on the basis of a literature review. The five variables studied are the Interest Rate, Removal of PDO Crashes, Crash Reduction Factors, Crash Rates, and Crash -- Flow Relationship. The focus of the evaluation is to compare the ranking of projects with respect to changes in the value of these input variables. The ranking are evaluated using various statistical methods, such as the Spearman Rank Order Correlation Test and Kendall's Tau Test. The results of the analysis indicated that, although changes in the value of input variables affect the SII output, the ranking of projects is usually not affected, with the exception of the crash reduction factor variable. Hence, the same projects will be selected for safety improvement, even if different values are used in the SII. Therefore, it is recommended that the current formulation of the SII and the value of input variables used in the formula be retained by TxDOT for prioritizing safety improvement projects. However, it is suggested to examine the accuracy and uncertainty associated with reduction factors, since in some cases they were found to affect the ranking of projects.

Thesis (M.A.) - Simon Fraser University, 2006. / Theses (School of Criminology) / Simon Fraser University. Also issued in digital format and available on the World Wide Web.

Thesis (Ph.D.)--University of Texas at Arlington, 2008.