Analysis of the effect of dust barriers on particulate matter dispersion from a construction site using CFD simulation

Urban construction activities generate particulate matter (PM), which poses a severe threat to urban residents' quality of life. The complex topography of urban areas and turbulent air flow make it difficult to predict PM dispersion and establish control measures. This study predicted PM dispersion from construction sites to urban areas under four wind directions using CFD simulations and determined optimal dust barrier heights for reducing PM exposure. This study showed that PM exposure on residents depends on wind directions in the urban area up to 2.3 times, still a flexible approach to determine optimal barrier heights based on stakeholder preferences was effective in all wind directions. Accurate PM dispersion predictions and control measures are crucial for improving urban air quality and residents' well-being.

The characteristics of PM emissions from construction sites during the earthwork and foundation stages: an empirical study evidence

The bulk of the particulate matter (PM) emissions generated during construction projects are significantly released during the earthwork and foundation stages. To reduce and control these emissions, it is necessary to have reliable data on their characteristics. However, construction PM are poorly characterized because their composition depends on several factors (e.g., weather and reduction measures) and various on-site activities whose effects may interact. To address these challenges, a long-term quantitative empirical study using advanced statistical methods was performed on a real construction project during the whole earthwork and foundation stages. The upwind-downwind method was used to collect data on PM emissions throughout the earthwork and foundation construction process, and correlation analysis, paired samples t-test, and partial least squares regression (PLS) were used to analyze TSP, PM₁₀, and PM_2.5 emissions and their relationships with various influencing factors. The results showed that both earthwork and foundation constructions generate substantial PM emissions because there were differences with statistical significances in the PM levels measured upwind and downwind of the construction site. TSP and PM₁₀ emissions correlated moderately with humidity and wind speed. However, temperature and atmospheric pressure did not correlate significantly with any of the measured emissions. The main activities responsible for PM emissions during the earthwork and foundation construction stages were hammer piling, waste stacking, and materials transportation. Water spraying was found to effectively reduce TSP and PM₁₀ emissions, while the use of a fog cannon more effectively reduced PM_2.5 emissions. Construction PM is an important source of atmospheric pollution in cities; the findings presented herein provide cornerstone and knowledge to guide efforts for reducing its impact.

Digital twins as education support in construction: a first development framework based on the Reference Construction Site Aachen West

The Reference Construction Site Aachen West, located in Aachen, Germany, is a campus-based living lab for research and university education in construction. To ensure and improve the education quality, this paper researches a new study tool in the form of a digital twin framework powered by the Unreal Engine. By implementing MQTT, an IoT communication protocol, the digital twin realizes synchronicity of cyber-physical bi-directional data flows. Representing the virtual Reference Construction Site, an online multiplayer application was developed as a use case to answer the research questions: (1) how to design the digital twin and structure in an extendable and accessible development framework for different users and (2) how to support education in construction with this digital twin. To validate the concept, a group of students were invited online to explore the application and provide user feedback. Results show positive effects of the digital twin on enhancing the quality of the online education in construction with its real-time interaction and data from on-site machinery and processes. The digital twin is planned to be transferred to research and construction projects.

COVID-19 recovery for the Nigerian construction sites: The role of the fourth industrial revolution technologies

Fourth industrial revolution (4IR) technologies have been proved as successful platforms to communicate and visualise construction projects within team meetings. These techniques possibly can enhance compliance with Covid-19 rules on sites. How far concerning Nigerian construction contractors in the use of 4IR technologies are yet to receive in-depth studies. Therefore, this paper offers a collective insight into the issues affecting construction firms from Covid-19 regarding lockdown rules and the role of 4IR technologies. Given the unexplored nature of the problem, a virtual face-to-face type of qualitative research method was employed. Twelve semi-structured interviews from selected construction firms and consultant experts were engaged and collated data analysed via a thematic approach. Findings group the 4IR technologies into smart construction site, simulation and modelling, and digitisation and virtualisation in Nigeria's context, and majority of the 4IR technologies can be useful to enhance Covid-19 compliance. Reluctant to adopt, high implementation cost, inadequate knowledge management, resistance to change, among others emerged as the factors hindering 4IR technologies usage. Findings will strengthen and provide a rich insight into the impact of Covid-19 on construction sites and contribute towards informing key stakeholders to create an enabling environment for the implementation of 4IR technologies on site.

Development of a real-time automated monitoring system for managing the hazardous environmental pollutants at the construction site

The management of noise, vibration, and dust, which are hazardous pollutants from construction sites, is essential to minimize the health damage of the nearby residents and the economic damage of construction companies due to pollutants from construction sites. For the effective management of hazardous pollutants, their emissions from construction sites must be identified immediately and accurately. Therefore, this study developed a real-time automated monitoring system named "MOnitoring for Noise, Vibration, and Dust (MONVID)" for comprehensively measuring the hazardous environmental pollutants and managing them in real-time. Toward this end, the optimal design of MONVID was planned and customized considering mobility, usability, and economy. Also, for the field application of the developed MONVID, its feasibility was verified by comparing its techno-economic performance with that of the conventional measurement system through experiments. Based on the results of the experiment and performance evaluation, it was concluded that MONVID is a feasible and economical construction pollutant measurement system with reliable technical performance and improved mobility and usability compared to the conventional measurement system. This study has significant contributions to the development of the first platform (including hardware, sensor network, and software) for the integrated real-time automated monitoring of the environmental performance of construction sites.

Dengue fever transmission between a construction site and its surrounding communities in China

BACKGROUND

Due to an increase in mosquito habitats and the lack facilities to carry out basic mosquito control, construction sites in China are more likely to experience secondary dengue fever infection after importation of an initial infection, which may then increase the number of infections in the neighboring communities and the chance of community transmission. The aim of this study was to investigate how to effectively reduce the transmission of dengue fever at construction sites and the neighboring communities.

METHODS

The Susceptible-Exposed-Infectious/Asymptomatic-Recovered (SEIAR) model of human and SEI model of mosquitoes were developed to estimate the transmission of dengue virus between humans and mosquitoes within the construction site and within a neighboring community, as well between each of these. With the calibrated model, we further estimated the effectiveness of different intervention scenarios targeting at reducing the transmissibility at different locations (i.e. construction sites and community) with the total attack rate (TAR) and the duration of the outbreak (DO).

RESULTS

A total of 102 construction site-related and 131 community-related cases of dengue fever were reported in our area of study. Without intervention, the number of cases related to the construction site and the community rose to 156 (TAR: 31.25%) and 10,796 (TAR: 21.59%), respectively. When the transmission route from mosquitoes to humans in the community was cut off, the number of community cases decreased to a minimum of 33 compared with other simulated scenarios (TAR: 0.068%, DO: 60 days). If the transmission route from infectious mosquitoes in the community and that from the construction site to susceptible people on the site were cut off at the same time, the number of cases on the construction site dropped to a minimum of 74 (TAR: 14.88%, DO: 66 days).

CONCLUSIONS

To control the outbreak of dengue fever effectively on both the construction site and in the community, interventions needed to be made both within the community and from the community to the construction site. If interventions only took place within the construction site, the number of cases on the construction site would not be reduced. Also, interventions implemented only within the construction site or between the construction site and the community would not lead to a reduction in the number of cases in the community.

Simple systems for treating pumped, turbid water with flocculants and a geotextile dewatering bag

Pumping sediment-laden water from excavations is often necessary on construction sites. This water is often treated by pumping it through geotextile dewatering bags. The bags are not designed to filter the fine sediments that create high turbidity, but dosing with a flocculant prior to the bag could result in greater turbidity control. This study compared two systems for introducing flocculant: passive dosing of commercial solid biopolymer (chitosan) and injection of dissolved polyacrylamide (PAM) in a length of corrugated pipe connected to the bag. The biopolymer system consisted of sequential porous socks containing a "charging agent" followed by chitosan in the corrugated pipe with two levels of dosing. The dissolved PAM was injected into turbid water at a flow-weighted concentration at 1 mg L(-1). For each treatment, sediment-laden turbid water in the range of 2000 to 3500 nephelometric turbidity units (NTU) was pumped into the upstream of corrugated pipe and samples were taken from pipe entrance, pipe exit, and dewatering bag exit. Without flocculant treatment, the dewatering bag reduced turbidity by 70% but the addition of flocculant increased the turbidity reduction up to 97% relative to influent. At the pipe exit, the low-dose biopolymer was less effective in reducing turbidity (37%) but it was equally effective as the high-dose biopolymer or PAM injection after the bag. Our results suggest that a relatively simple treatment with flocculants, either passively or actively, can be very effective in reducing turbidity for pumped water on construction sites.

Behavior-based safety on construction sites: a case study

This work presents the results of a case study and describes an important area within the field of construction safety management, namely behavior-based safety (BBS). This paper adopts and develops a management approach for safety improvements in construction site environments. A rigorous behavioral safety system and its intervention program was implemented and deployed on target construction sites. After taking a few weeks of safety behavior measurements, the project management team implemented the designed intervention and measurements were taken. Goal-setting sessions were arranged on-site with workers' participation to set realistic and attainable targets of performance. Safety performance measurements continued and the levels of performance and the targets were presented on feedback charts. Supervisors were asked to give workers recognition and praise when they acted safely or improved critical behaviors. Observers were requested to have discussions with workers, visit the site, distribute training materials to workers, and provide feedback to crews and display charts. They were required to talk to operatives in the presence of line managers. It was necessary to develop awareness and understanding of what was being measured. In the process, operatives learned how to act safely when conducting site tasks using the designed checklists. Current weekly scores were discussed in the weekly safety meetings and other operational site meetings with emphasis on how to achieve set targets. The reliability of the safety performance measures taken by the company's observers was monitored. A clear increase in safety performance level was achieved across all categories: personal protective equipment; housekeeping; access to heights; plant and equipment, and scaffolding. The research reveals that scores of safety performance at one project improved from 86% (at the end of 3rd week) to 92.9% during the 9th week. The results of intervention demonstrated large decreases in unsafe behaviors and significant increases in safe behaviors. The results of this case study showed that an approach based on goal setting, feedback, and an effective measure of safety behavior if properly applied by committed management, can improve safety performance significantly in construction site environments. The results proved that the BBS management technique can be applied to any country's culture, showing that it would be a good approach for improving the safety of front-line workers and that it has industry wide application for ongoing construction projects.