Due to the economic growth and improvement of the construction industry witnessed by most countries, there has become a crucial need for employing modern possibilities in the construction sector to build taller, longer and deeper structures. However, one aspect that heads forward with the same intensity is the generation of 100 million tons of construction waste every year. This generation has occurred due to several factors with different levels of importance. Hence, this study reveals 15 factors influencing construction waste generation and categorizes them into 3 groups, (materials management on site), (materials handling, transportation and storage) and (site management and practices). A questionnaire survey of 100 respondents was distributed among different engineers to assess the construction waste factors. Results showed that damage of materials on site, double handling of materials and incompetent contractor’s technical staff were the most significant factors of each category with Relative Importance Indexes (RII) of 0.866, 0.844 and 0.83, respectively. These findings will help the practitioners to reduce construction waste quantities in sites and improve waste management performance factors to control the construction waste problems.

Productivity is a very important element in the estimation process in construction management. The objective of this research is to identify and analyze the factors which affect labor productivity in construction projects. In this research, 42 effective factors were collected from site survey, interview with engineers and experts, and previous research in the Arab world. These factors are grouped into Nine categories “Workforce, Leadership, Motivation, Supervisors, Safety, Project, Time, Material, and External”. A survey questionnaire of 70 respondents was distributed among different experts. A statistical analysis was done using SPSS and EXCEL packages. The Relative Importance Index was used to find out the most significant factors affecting the labor productivity in construction sites. The results accomplished from the survey revealed that the major factors negatively affect the labor productivity (ranked from the worst factor with Relative Importance Index values, respectively) namely, Availability Material (88.571%), Climate status “Weather” (88%), Religious occasions (86.29%), Number of working groups (86%), Ganger experience (85.714%), Workforce surveillance (84.857%), Ganger Age (84%), working at height (82%), Drawings and specifications alteration during execution (81.69%), and Sequence of floor (80.571%). Based upon these findings, this can help the construction professionals to improve the productivity and project performance in Iraq.

The productivity rate is the main indicator for the development of construction projects for any developed country. The main goal of this paper is to evolve a mathematical model by using the multiple linear regression technique to predict the rate of production of concrete column molds. This is because the currently used methods in estimating productivity, such as the methods that rely on personal experience and old data, are traditional methods characterized by inaccuracy. So, there was a need to adopt new techniques to estimate the construction productivity in an accurate, fast, and easy way. In this study, eleven factors were identified which are the most affecting factors on construction productivity. They are considered independent variables that affect the productivity rate of the item column formworks. The dependent variable is the construction productivity. The work measurement form was designed for the purpose of collecting real initial data from the site. This model is based on 36 samples of data collected from various projects of Multi-story buildings for residential and commercial buildings, which are used to build the model and verify its performance. From the results of the multiple linear regression MLR results, an equation was derived to calculate the construction productivity of the column formworks. It was found that the multi-linear regression model provides a very good predictability of productivity (82.31%), and the correlation coefficient (R%) was 97.15%. The results showed that the relationship between the independent variables for "the built-in model is very good, and the values"calculated from the prediction model are commensurate with actual data".

Residential complex projects represent one of the most important infrastructure project types in Iraq, as these plays a significant role in housing provision. In recent years, various types of risks that may occur during the implementation stage of residential complex projects have been identified. To accomplish these projects successfully, it is thus very important to manage these risks where they may affect project objectives in terms of cost, time, and quality, and risks often cause delays or cost overruns. The concept of risk management is to develop a systematic process that includes planning, identification, response planning, analysis, and assessment of both qualitative and quantitative variables, monitoring and mitigation of risks. This research thus aims to identify, assess and analyse the factors related to risks that may affect the implementation time for residential complexes projects by means of conducting statistical analysis using IBM SPSS v22 and Microsoft Excel to determine the severity risk for such project risks based on a relative importance index. This data for this was gathered by means of a questionnaire, field survey, and personal interviews. The questionnaire consisted of three parts, with the first part including general information about the sample; the second part included 17 queries about applications of risk management systems as a methodology; and the third part discussed the probability of occurrence and impact of risks, with 57 factors considered. The results of the statistical analysis showed that only four out of the 17 items in section 2 were applied; further, by analysing responses to the 57 factors, only 25 factors were found to have high impacts on risk occurrence in residential complex projects in Iraq. This suggests that only 44% of time overruns in residential complex projects may occur due to risk factors. The most important factors in terms of high impact are executing works that do not conform to specifications, which leads to rejecting and returning works, inaccuracy of schedule, and delayed payment of advances in accordance with the contract.

Simulation and computational techniques cover a variety of aspects also had proved its feasibility in construction management as whole, so it had adopted by a lot of researches during the last decades with rapid progress. The current study presents a focused review about construction cost simulation using, and provides an overview of such advancements achieved between 1990 and 2016 in construction management sector. This paper focuses specifically on many different topics including construction cost simulation, simulation modelling concept, steps of simulation conducting, simulation purposes, simulation advantages and disadvantages, etc.  Major advances in construction cost simulation area are highlighted, as well as the trends for development and application. Over the selected study period, there has been a substantial increase in the use of high-fidelity simulation in construction cost management.