Human-Induced or Natural Hazard? Factors influencing perceptions of actions to be taken in response to induced seismicity

A relatively new term for categorizing hazards is that of &ldquo;techna&rdquo; hazards, or seemingly natural phenomena induced by human technology or activity. The human origin of these hazards means that mitigation aimed at addressing the underlying cause of the hazard is a possibility, which is often not considered possible with traditional natural hazards. Currently, however, there is a dearth of literature regarding how perceptions of the underlying cause of the hazard influences beliefs regarding disaster risk reduction strategies for the hazard. Thus, this work examines the factors that predict beliefs regarding whether a techna hazard can be stopped or reduced, the best actions that should be taken to reduce or stop the hazard event, and whether current regulation efforts aimed at stopping or controlling the activities causing the hazard are enough. We specifically examine the case of fluid injection induced seismicity in Oklahoma and Colorado in the United States. We find that, contrary to our expectations from prior literature, exposure to the hazard is not a strong predictive factor of these beliefs. Perceptions of the underlying activity associated with the hazard, in this case hydraulic fracturing and oil and gas development, is significant, in that those with more positive views of the industry activity are more likely to believe the earthquakes cannot be stopped and favor less intense regulative efforts to address the hazard. &nbsp;</p

Representing Uncertainty in Natural Hazard Risk Assessment with Dempster Shafer (Evidence) Theory

This paper explores and develops different mathematical frameworks to address the representation of inherent uncertainties such as those often involved in the assessment of natural hazard risk for the built environment. To date, little exploration has been performed of such theories, inhibiting the progress and use of these potentially well-suited frameworks, especially to applications for expert evidence in the field of sustainable and resilient infrastructure. One such framework, Dempster-Shafer Theory, allows the combination of multiple expert beliefs while considering uncertainties that are often ingrained in this field. In cases such as seismic hazards, for which structural vulnerability and structural damage are evaluated in a case-by-case scenario, subjective assessments are not only useful but necessary. This research performs a rigorous exploration to determine the behavior and trends of Dempster-Shafer Theory, including a mathematical proof of asymptotic behavior, in an attempt to both (a) understand how this framework handles confidence, ignorance, and combined beliefs, and (b) encourage the use of more natural frameworks in cases that involve uncertainty. The results of this exploration suggest that probability may not be the most natural framework in which to quantitatively incorporate the involved uncertainty. Ignorance and evidence-based assessments may be better represented using Dempster Shafer Theory.</p

Optimal pavement maintenance programs based on a hybrid Greedy Randomized Adaptive Search Procedure Algorithm

Insufficient investment in the public sector together with inefficient maintenance infrastructure programs lead to high economic costs in the long term. Thus, infrastructure managers need practical tools to maximize the Long-Term Effectiveness (LTE) of maintenance programs. This paper describes an optimization tool based on a hybrid Greedy Randomized Adaptive Search Procedure (GRASP) considering Threshold Accepting (TA) with relaxed constraints. This tool facilitates the design of optimal maintenance programs subject to budgetary and technical restrictions, exploring the effect of different budgetary scenarios on the overall network condition. The optimization tool is applied to a case study demonstrating its efficiency to ana­lyze real data. Optimized maintenance programs are shown to yield LTE 40% higher than the traditional programs based on a reactive strategy. To extend the results obtained in this case study, a set of simulated scenarios, based on the range of values found in the real example, are also optimized. This analysis concludes that this optimization algorithm enhances the allocation of maintenance funds over the one obtained under a traditional reactive strategy. The sensitivity analysis of a range of budgetary scenarios indicates that the funding level in the early years is a driving factor of the LTE of optimal maintenance programs

Dempster-Shafer Theory Applications in Structural Damage Assessment and Social Vulnerability Ranking

This thesis explores the different mathematical frameworks that have been used in risk assessment, with an emphasis on Dempster-Shafer Evidence Theory and the applicability in cases of post seismic structural damage assessments and social vulnerability ranking. Evidence Theory allows the combination of multiple expert beliefs while considering uncertainties that are often inherent in such evaluations. In cases such as seismic hazards, for which structural vulnerability and structural damage are evaluated in a case-by-case scenario, subjective assessments are not only useful but necessary. The results of experimentation and survey distribution suggest that probability may not be the most natural framework in which to quantitatively incorporate the involved uncertainty. Ignorance and evidence-based assessments may be better represented using Evidence Theory.</p

Challenges in Engineering Estimates for Best-Value Design-Build Highway Projects

Traditional design&ndash;bid&ndash;build guidelines suggest that engineering estimates should be within +/&minus;10% of the lowest contractor bid and recommend this value as a reference to identify anomalies in the bidding process. This guidance, however, neglects delivery approaches such as design&ndash;build (D&ndash;B). This research examines 305 D&ndash;B highway projects procured using best-value and identifies the underlying reasons for bid dispersion and cost estimates inaccuracies. This study found an average bid dispersion of 27%, suggesting that a larger threshold (i.e., 25%) is needed to account for the inherent variability of D&ndash;B projects. This study also found that engineering estimates are on average 2% more than the awarded price. This result contradicts findings in existing literature and suggests that current practice in D&ndash;B best-value may be more conservative than other procurement methods. The study explores four potential reasons for bid dispersion and engineering estimate inaccuracies and suggests strategies for improvement. By providing a better understanding of bid dispersion and engineering estimate accuracy, this study will ultimately assist in the development of new policies and processes for D&ndash;B best-value projects.</p

Structured Approach for Best-Value Evaluation Criteria: US Design–Build Highway Procurement

In best-value procurement, current practice shows that cost is frequently more influential than noncost factors, and consequently, the lowest bidder is chosen in most cases; thus, a best-value selection is not achieved. Design-builders cannot offer the best value in their proposals if evaluation criteria do not show precisely what constitutes best value and how best value is scored. Thus, the aim of this research is twofold: first, to identify how highway agencies articulate evaluation criteria and, second, to propose a structured approach that enhances current practice on writing evaluation criteria. Through the lens of decision analysis, the researchers conducted a content analysis on 540 evaluation criteria included in 98 requests for proposal (RFPs) from 21 states across the United States. The study showed that 43% of evaluation criteria were generic, 53% used a generic constructed scale, and 4% assigned points or levels directly. These three groups represent different levels of specificity in writing evaluation criteria. Building upon these levels and on decision analysis theory principles, this research proposes a structured approach to support highway agencies in the process of crafting evaluation criteria. More precise and specific evaluation criteria will enhance the proposals&rsquo; ability to offer the best value, which, in turn, will enhance the best-value selection process as a whole. &nbsp;</p

Importance of Noncost Criteria Weighing in Best-Value Design–Build US Highway ProjectsE DESIGN-BUILD U.S. HIGHWAY PROJECT

United States highway agencies use best-value procurement with a fixed price to select design-builders.&nbsp; This method enables public agencies to choose the best proposer by assessing several factors in addition to price. Theoretically, considering cost and non-cost factors in the selection enhances the probability of selecting the proposer that provides the best value for each dollar spent.&nbsp; However, bidding results from the last 15 years show that 80% of best-value procurements are awarded the proposer with the lowest bid.&nbsp; The selection seems thus to be biased towards price. This research explores the balance between cost and non-cost components in best-value procurement by identifying how weights and scores influence the selection. The goal of this analysis is to determine the ranges of weights that better balance cost and non-cost factors in the weighted criteria best-value procurement. This study characterized a first-of-a-kind dataset of 882 non-cost scores and 1,158 cost scores from 347 best-value highway projects. The study applied simulation to the weighted criteria award algorithm to explore the balance between cost and non-cost factors and derive recommendations about how to make non-cost factors more influential. The results show that weight of cost higher or equal to 57% will result in a lowest price selection. Highways agencies should be aware of how weights and scores impact the best-value selection so that they can align these elements with their selection objectives.</p

Sustainability Evaluation of Pavement Technologies through Multicriteria Decision Techniques

This paper presents findings of a recent study that was conducted in Canada on the quantification of pavement sustainability. The ultimate goal of this study was to develop a framework and explore the use of multicriteria decision-making techniques to formally assess the sustainability of pavement engineering alternatives. While sustainability is of increasing concern in pavement engineering, environmental performance is rarely used by pavement managers to select maintenance practices. There is therefore a need to develop a framework for the practical consideration of environmental effects in pavement management. This paper aims to provide a better understanding on the use of multicriteria decision-making techniques based on hierarchy process (AHP) and choosing by advantages (CBA) for the integration of sustainable aspects in the decision-making process of pavement management. A case study comparing pavement maintenance technologies using cold-in-place recycling and traditional solutions based on mill and overlay is analyzed for illustrative purposes. Results obtained using both multicriteria techniques are compared, including a sensitivity analysis on the importance of sustainability criteria in the evaluation of maintenance alternatives. Results obtained from this case study show that AHP and CBA provide consistent recommendations in which cold-in-place technologies are preferred over traditional alternatives. However, CBA presents the advantage of separating cost from the analysis, letting the agency to decide whether they are willing to pay more to use more sustainable alternatives. This finding has significant implications for engineering practice, given that AHP is widely used not only in the pavement field but in infrastructure management. Further research is needed to incorporate social aspects and existing barriers for the implementation of sustainable technologies in the proposed sustainability evaluation.</p

Height and body-mass index trajectories of school-aged children and adolescents from 1985 to 2019 in 200 countries and territories: a pooled analysis of 2181 population-based studies with 65 million participants

Summary Background Comparable global data on health and nutrition of school-aged children and adolescents are scarce. We aimed to estimate age trajectories and time trends in mean height and mean body-mass index (BMI), which measures weight gain beyond what is expected from height gain, for school-aged children and adolescents. Methods For this pooled analysis, we used a database of cardiometabolic risk factors collated by the Non-Communicable Disease Risk Factor Collaboration. We applied a Bayesian hierarchical model to estimate trends from 1985 to 2019 in mean height and mean BMI in 1-year age groups for ages 5–19 years. The model allowed for non-linear changes over time in mean height and mean BMI and for non-linear changes with age of children and adolescents, including periods of rapid growth during adolescence. Findings We pooled data from 2181 population-based studies, with measurements of height and weight in 65 million participants in 200 countries and territories. In 2019, we estimated a difference of 20 cm or higher in mean height of 19-year-old adolescents between countries with the tallest populations (the Netherlands, Montenegro, Estonia, and Bosnia and Herzegovina for boys; and the Netherlands, Montenegro, Denmark, and Iceland for girls) and those with the shortest populations (Timor-Leste, Laos, Solomon Islands, and Papua New Guinea for boys; and Guatemala, Bangladesh, Nepal, and Timor-Leste for girls). In the same year, the difference between the highest mean BMI (in Pacific island countries, Kuwait, Bahrain, The Bahamas, Chile, the USA, and New Zealand for both boys and girls and in South Africa for girls) and lowest mean BMI (in India, Bangladesh, Timor-Leste, Ethiopia, and Chad for boys and girls; and in Japan and Romania for girls) was approximately 9–10 kg/m2. In some countries, children aged 5 years started with healthier height or BMI than the global median and, in some cases, as healthy as the best performing countries, but they became progressively less healthy compared with their comparators as they grew older by not growing as tall (eg, boys in Austria and Barbados, and girls in Belgium and Puerto Rico) or gaining too much weight for their height (eg, girls and boys in Kuwait, Bahrain, Fiji, Jamaica, and Mexico; and girls in South Africa and New Zealand). In other countries, growing children overtook the height of their comparators (eg, Latvia, Czech Republic, Morocco, and Iran) or curbed their weight gain (eg, Italy, France, and Croatia) in late childhood and adolescence. When changes in both height and BMI were considered, girls in South Korea, Vietnam, Saudi Arabia, Turkey, and some central Asian countries (eg, Armenia and Azerbaijan), and boys in central and western Europe (eg, Portugal, Denmark, Poland, and Montenegro) had the healthiest changes in anthropometric status over the past 3·5 decades because, compared with children and adolescents in other countries, they had a much larger gain in height than they did in BMI. The unhealthiest changes—gaining too little height, too much weight for their height compared with children in other countries, or both—occurred in many countries in sub-Saharan Africa, New Zealand, and the USA for boys and girls; in Malaysia and some Pacific island nations for boys; and in Mexico for girls. Interpretation The height and BMI trajectories over age and time of school-aged children and adolescents are highly variable across countries, which indicates heterogeneous nutritional quality and lifelong health advantages and risks

Repositioning of the global epicentre of non-optimal cholesterol

High blood cholesterol is typically considered a feature of wealthy western countries1,2. However, dietary and behavioural determinants of blood cholesterol are changing rapidly throughout the world3 and countries are using lipid-lowering medications at varying rates. These changes can have distinct effects on the levels of high-density lipoprotein (HDL) cholesterol and non-HDL cholesterol, which have different effects on human health4,5. However, the trends of HDL and non-HDL cholesterol levels over time have not been previously reported in a global analysis. Here we pooled 1,127 population-based studies that measured blood lipids in 102.6 million individuals aged 18 years and older to estimate trends from 1980 to 2018 in mean total, non-HDL and HDL cholesterol levels for 200 countries. Globally, there was little change in total or non-HDL cholesterol from 1980 to 2018. This was a net effect of increases in low- and middle-income countries, especially in east and southeast Asia, and decreases in high-income western countries, especially those in northwestern Europe, and in central and eastern Europe. As a result, countries with the highest level of non-HDL cholesterol—which is a marker of cardiovascular risk—changed from those in western Europe such as Belgium, Finland, Greenland, Iceland, Norway, Sweden, Switzerland and Malta in 1980 to those in Asia and the Pacific, such as Tokelau, Malaysia, The Philippines and Thailand. In 2017, high non-HDL cholesterol was responsible for an estimated 3.9 million (95% credible interval 3.7 million–4.2 million) worldwide deaths, half of which occurred in east, southeast and south Asia. The global repositioning of lipid-related risk, with non-optimal cholesterol shifting from a distinct feature of high-income countries in northwestern Europe, north America and Australasia to one that affects countries in east and southeast Asia and Oceania should motivate the use of population-based policies and personal interventions to improve nutrition and enhance access to treatment throughout the world