Greenhouse gas emissions associated with road transport projects: current status, benchmarking, and assessment tools

Global warming and climate change have been two much-debated topics in recent times due to their malevolent consequences not only to ecosystems, but also to the human race. They are indeed negative by-products of greenhouse gas (GHG) emissions. The transportation sector is a major contributor of GHG emissions, accounting for approximately 20 percent of all carbon dioxide (co2) emissions globally, and road transportation accounts for the large majority of those emissions. This paper reviews literature related to GHG emissions produced by construction, operation, and maintenance phases of road projects. It compares country-specific GHG emission levels and provides input on assessment tools that can be used to estimate road project-specific GHG emissions. Lastly, the paper draws conclusions in regards to the magnitude of GHG emissions produced by road transportation, as well as to the status of assessment tools readily available in the market. The authors find that GHG emissions continue to be a concern, especially in the Gulf Cooperation Countries (GCC), and recognize the need for reliable modeling tools capable of estimating project-specific GHG emissions. As a result, a model framework is proposed as the first step towards a comprehensive modeling tool capable of estimating GHG emissions produced during the entire life-cycle of a road project. The authors disclose that such tool is currently under development

A Survey on the Use of Plastic versus Biodegradable Bottles for Drinking Water Packaging in the United Arab Emirates

Due to intensive utilization and extensive production, plastic waste is becoming a serious threat to the environment and human health. The situation is even worse in countries such as the United Arab Emirates (UAE), where single-use plastic water bottles add to the load of plastic pollution. The main objective of this survey was to assess the extent of bottled water utilization by the UAE residents and their awareness of the environmental concerns arising from single-use plastic bottles. The aim was also to evaluate their willingness to shift towards using biodegradable plastic bottles. This study involved the feedback of 2589 respondents living in the UAE. The eigenvalue decomposition (EVD) was applied to determine the most responsible variables explaining the variability of our data set. A chi-square analysis was also used to determine the significance among the responses. Most of the respondents to this survey were UAE nationals (79.8%) of ages ranging from 21 to 35 years (42%), who were educated, with most holding a university degree (69.6%). Regardless of their gender, age, occupation, education, and income, a large group of respondents (40.7%) was concerned about the impact of their purchased items on the environment; however, the frequency of plastic products recycled was observed to be low (49.7%). According to the findings of this survey, 42.4% of the respondents were likely to purchase 100% biodegradable bottles, and about 70% of the respondents expressed a willingness to spend at least AED 1 more for purchasing 100% biodegradable bottles

Methods of Determining Retardation Coefficients of Organic Compounds in Aquifers

 Sorption is an important mechanism that affects the mobility of organic compounds in the subsurface environment. Sorbed compounds move slower than that of groundwater, causing retardation in their movement. Accurate determination of retardation coefficients (R) of organic compounds in aquifers is critical for understanding their movement, fate, and remediation. Several methods, including predictive tools, laboratory experiments, and field experiments have been utilized for determining sorption-related retardation. The objective of this paper was to review and compare between the different methods used for the determination of R of organic compounds, with emphasis on predictive- and laboratory-based approaches. Predictive tools are based on the use of quantitative structure-activity relationships (QSARs). Laboratory methods utilize different types of reactors including batch, stirred-flow, circulation-through-column, or miscible displacement through packed columns. In addition, data from the column method have been analyzed in various ways to determine R. Discrepancies between results from different methods or from different analysis approaches have been reported. This create uncertainty about the suitability of some of these methods or the used analysis approaches. This paper highlights the possible causes for the observed discrepancy and establishes the limitations and appropriateness of the used methods and analysis approaches

Development of a Composite Sustainability Index for Roadway Intersection Design Alternatives in the UAE

Many studies have been carried out to evaluate the sustainability of transportation systems, but little attention has been given for the design of roadway intersections. This study aimed to establish a framework and develop a tool to assess the sustainability of roadway intersections from a road-user perspective. Sustainability indicators at the strategic level were extracted from the literature and were utilized with relative weights to develop economic, environmental, and social indices that would be combined into a composite sustainability index (CSI) tool. The tool was applied to four case studies of intersections in Al Ain, United Arab Emirates. For each case study, the sustainability of fifteen design alternatives was evaluated for different scenarios of traffic volume and operational speed. Dimensional indices and the overall CSI were determined using the Multi-Criteria Decision Making method. Results indicated that traffic volume had a significant impact on intersection sustainability ranking, while the effect of operational speed was insignificant. Moreover, weight assignment had an effect on determining the most sustainable design alternative, where the best alternatives of the dimension with the major weight would most likely be the most sustainable. The developed tool would assist decision-makers in other cities to assess intersection projects that correspond to their regional goals

Use of Nanoparticles for the Disinfection of Desalinated Water

When chemical disinfection is performed before or after desalination, a number of harmful compounds are formed. Thus, efforts have been directed toward developing alternative methods for water disinfection. In this study, seven nanoparticles (NPs) were evaluated for disinfecting water produced from reverse osmosis and multi-stage flash desalination plants. The tested NPs were silver, copper, silver-copper, zinc oxide, magnesium oxide, silicon dioxide, and carbon nanotubes. The antimicrobial activity of the NPs was investigated by batch studies in desalinated water samples spiked with E. coli, Enterobacter, Salmonella, and Enterococci. The Chick-Watson model was fitted to the inactivation data to evaluate the kinetic constant for each combination of NPs, water type, and indicator bacteria. The results indicated that silver and silver-copper NPs have the highest disinfection efficiency among the tested NPs. Among the bacteria, Enterobacter (strain TPC129) appears to be the most inactivated, while Enterococci (strain NCTC775) seems to be the least influenced by the NPs. Variations in the chemical characteristics of the tested water samples appeared to cause noticeable differences in the antibacterial efficacies of copper and magnesium oxide NPs, but not in those of the other NPs

GHG Emission Reduction Opportunities for Road Projects in the Emirate of Abu Dhabi: A Scenario Approach

The transportation sector is considered one of the driving forces behind the increased release of greenhouse gases (GHGs), with road transport being this sector’s main emissions contributor. In turn, efforts should be devoted to reducing emitted GHGs from this sector, and many such opportunities lie in the road transport life cycle. This paper investigated fourteen emission reduction scenarios based on the green initiatives issued by the Abu Dhabi Government. The explored measures are either related to road works and road municipal services or to traffic movement. The proposed measures were evaluated with reference to a baseline study previously reported by the authors for three different road projects in Abu Dhabi city. Findings reveal that normalized GHG emission reduction could be significantly reduced by (i) replacing 30% of internal combustion engine passenger cars with battery electric vehicles where the power demand is covered almost equally from nuclear and liquified natural gas (LNG) sources, (ii) reducing the number of passenger cars by 10%, and (iii) having one-fifth of passenger cars powered by LNG. A lesser significant reduction could be achieved by replacing conventional lamps with light-emitting diode (LED) lamps or by having one-fourth of lighting powered by solar energy. Even lesser reduction could be achieved by (i) replacing a portion of Portland cement with ground granulated blast furnace slag in concrete structures, (ii) fully utilizing treated sewage effluent for roadside-plant irrigation, (iii) reducing desalinated water used for roadside-plant irrigation by 20%, and (iv) increasing the number of higher efficiency passenger cars by 10%. Replacing hot-mix asphalt with warm-mix asphalt and using asphalt with a high stiffness modulus in the base layer results in low emission reduction. The use of 15% recycled asphalt or the use of 50% recycled aggregate in road construction has the least impact on emission reduction. When all explored scenarios were combined, an overall normalized GHG emissions reduction of 9–17% during the road project life cycle could be achieved

RoadCO2: a web-based tool for estimation of greenhouse gas emissions of road projects

A number of countries have recognized the need to quantify the greenhouse gas (GHG) emissions produced by road transportation. As a result, several estimation tools have been developed during the last decade. However, the available tools do not capture all activities contributing to GHG emissions during the life cycle of road projects. This paper describes the development of a comprehensive web-based tool that can be used to quantify direct and embodied emissions from all activities associated with different phases of road projects. The tool, called RoadCO2, accounts for all possible activities that may be encountered during the pre-construction, construction, operation, maintenance, and rehabilitation phases of a road project. Although RoadCO2 currently uses emission factors established by the Intergovernmental Panel on Climate Change (IPCC), the tool has the flexibility to accommodate country-specific emission factors, if available

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