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Waste is typically encountered during the building's life cycle, from the design phase, through the construction phase, to modification and demolition. Most of these construction wastes are unnoticed or unattended by project managers, which lead to serious environmental problems. Effective waste reduction strategies will require a thorough and detailed understanding of the causes of construction waste. Hence, this paper aims to explore critical waste factors (CWFs) affecting the performance of construction projects.

An extensive literature review was carried out to determine these factors based on previous studies, from which a questionnaire was developed. Series of statistical analyses such as reliability analysis, Spearman Correlation, Kruskal–Wallis and factor analysis were performed on a total of 330 valid responses to identify latent factors responsible for wastes occurrence.

This study reveals 31 CWFs through evaluation of prior relevant studies carried out in several countries and then adjusted and validated through semistructured interviews. The significant differences in views within various groups of respondents with different organizational characteristics are highlighted. The results of factor analysis showed that there are six principal components extracted with 66.3% of variance explained (material-related factors; subcontractors and workers; planning, communication and coordination; people involvement and financial issues; people development strategies; and external factors).

This study differs from other studies in the literature by gathering all relevant waste factors including those related to nonphysical waste such as time, budget, workers and equipment. Furthermore, this paper will be of great interest to both practitioners and researchers since it brings various recommendations concerning the prevention/reduction of waste through lean construction for more sustainable construction projects.

Lean construction (LC) consists of very effective techniques; however, its implementation varies considerably from one industry to another. Although numerous lean initiatives do exist in the construction industry, the research topic related to LC implementation is still unexplored due to the scarcity of validated assessment frameworks. This study aims to provide the first attempt in developing a structural model for successful LC implementation.

This study developed a Lean construction model (LCM) by critically reviewing seven previous LC frameworks from different countries, defining 18 subprinciples grouped into 6 major principles and formulating testable hypotheses. The questionnaire was pre-tested with 12 construction management experts and revised by 4 specialized academics. A pilot study with 20 construction units enhanced content reliability. Data from 307 Moroccan construction companies were collected to develop a measurement model. SPSS V. 26 was used for Exploratory Factor Analysis, followed by confirmatory factor analysis using AMOS version 23. Finally, a structural equation model statistically assessed each construct's contribution to the success of LC implementation.

This work led to the development of an original LCM based on valid and reliable LC constructs, consisting of 18 measurement items grouped into 6 LC principles: Process Transparency, People involvement, Waste elimination, Planning and Continuous improvement, Client Focus and Material/information flow and pull. According to the structural model, LC implementation success is positively influenced by Planning and Scheduling/continuous improvement (β = 0.930), followed by Elimination of waste (β = 0.896). Process transparency ranks third (β = 0.858). The study demonstrates that all these factors are mutually complementary, highlighting a positive relationship between LC implementation success and the holistic application of all LC principles.

To the best of the authors’ knowledge, this study is the first attempt to develop a statistically proven model of LC based on structural equation modelling analysis, which is promising for stimulating construction practitioners and researchers for more empirical studies in different countries to obtain a more accurate reflection of LC implementation. Moreover, the paper proposes recommendations to help policymakers, academics and practitioners anticipate the key success drivers for more successful LC implementation.

This research seeks to evaluate the impact of applying lean construction principles on the performance of reinforcement operations using a discrete-event simulation (DES) approach.

Process mapping of reinforcements operations was first established through field observation and interviews with construction managers involved in the selected project. Subsequently, quantitative data were gathered and then used to identify the best probabilistic density functions for each activity duration based on the fit-quality tests. Upon testing the validity of the real-world model, a lean simulation model was developed, using ARENA software, to investigate the impact of lean construction principles on the performance of such processes.

Lean principles are effective in enhancing the performance of the selected construction process. Output performance measurements for real-world model and lean model revealed that lean construction principles led to 41% improvement in process productivity, 14% enhancement in process efficiency and 17% reduction in cycle time.

The statistical findings only represent the process under study (reinforcement process) and cannot be generalized to other construction activities. In order to draw generalizable conclusions, future works are needed to extend this study to different project sizes and more complex construction processes (e.g. bricklaying process and concrete pouring operations). Moreover, there are other factors such as labor skills, rework and uncertainty, site conditions that require further analyses for leaner construction projects.

The methodology and the techniques presented in this work can be used for decision making by analyzing various lean construction scenarios and evaluating their impacts on performance outcomes of any construction process prior to real-world implementation.

Lean construction provides innovative practices to manage construction projects while reducing waste and improving performance. This paper aims to explore the current level of awareness of lean construction practices among Moroccan construction professionals to assess the potential benefits derived from lean construction practices and to identify the critical barriers hindering a successful implementation.

The paper opted for a quantitative approach by using a structured questionnaire survey. A total of 330 valid responses were collected from Moroccan construction practitioners involved in private and public construction organisations.

The results show that 61 per cent of the respondents are familiar with lean construction practices. The findings have also pointed out that the lean construction approach adds a positive impact, specifically on quality, safety and environmental level. In addition, the main barriers hindering a successful lean construction deployment in Morocco are lack of knowledge about lean construction philosophy, unskilled human resources and insufficient financial resources.

This study provides a new insight into the implementation of lean construction in Morocco. It contributes to the body of knowledge, as it uncovers for the first time the level of awareness, the potential benefits derived from lean construction practices and the barriers to implementing lean construction in the Moroccan construction industry. Exploring the current state of lean construction implementation can help practitioners, companies and researchers in the Moroccan construction industry to focus their effort and resources on the significant issues necessary to assist a successful implementation of lean construction. Furthermore, the findings of this study could prove valuable to other countries in Africa, especially those sharing similarities to the Moroccan context.

The purpose of this study is to determine whether there is a correlation between mobilization costs and project schedule performance of highway projects. In addition to this, the study will also determine if the mobilization costs are helping small or large highway projects in terms of improving the schedule performance.

The data of 206 highway projects were collected from the Department of Transportation of two states with the help of questionnaire survey. The cost, schedule and mobilization costs data were collected. The performance metrics related to construction schedule growth and construction intensity were developed in order to test the research hypotheses: mobilization costs will increase the schedule performance of highway projects. The data were also divided into two groups based on project cost and analyzed to check whether the mobilization costs impact the schedule performance of these highway projects. Spearman's correlation test was conducted to determine the correlation between dependent and independent variables. In addition, a Mann–Whitney test was conducted to determine the difference in medians of construction schedule growth and the construction intensity of these two groups of projects.

One major study finding was that there was no strong linear correlation between the mobilization cost percentage and the construction schedule growth and construction intensity of highway projects. However, the study found the projects that have 9% or more mobilization costs had significantly better schedule growth compared to the projects that have less than 9% mobilization costs. When data were analyzed based on the project size, it was found that this pattern was seen only in large projects costing equal to or more than $5 million.

This study's findings have very crucial practical implications to state DOTs contract engineers. This study shows that the highway contract engineers need to provide the right amount of mobilization costs to complete their projects on and before schedule. If the correct amount of mobilization costs is not provided to the contractors, the impact of these mobilization costs on reducing the schedule growth will be negligible. The findings of this study will assist public agency decision makers to complete their projects on or before time by including the mobilization costs provision in the contract. The state DOTs can improve their schedule performance by providing enough financial help to the contractors so that they can improve their cash flows and complete projects successfully within the given timeframe.

This paper contributes to the existing body of knowledge by validating the impact of mobilization costs on the schedule performance of highway projects. There has been no empirical study conducted prior to this to identify the role of mobilization costs on reducing the schedule growth of highway projects.