Improving construction processes by integrating lean, green, and six-sigma

The overall goal of this research was to develop and implement methods to improve the performance and the efficiency of construction processes prior to and during the construction phase in Design-Bid-Build (DBB) projects. In order to accomplish these goals, the three methods Lean, Green, and Six-Sigma were implemented in two different scenarios and validated by case studies.;First, a framework was developed that integrated the three methods - Lean, Green, and Six-Sigma with an overall layout of the Define, Measure, Analyze, Improve, and Control (DMAIC) improvement model. The framework was then validated through the construction process of installation of pile caps for an educational institute during the construction phase in Pittsburgh. The framework highlighted two issues with the pile caps construction process. First, disparate quantities of materials (purchased and installed) were determined. Second, the pile caps construction process took a total time of 54 business days while it could have been completed in 30 business days. Using life cycle assessment, environmental impacts of the pile cap construction process were analyzed and results showed that major environmental impacts including global warming potential, release of carcinogenics, negative respiratory effects, ozone depletion, and ecotoxcity could result from the materials used for the process. Next, the root causes behind waste generation were determined via developing and administrating a questionnaire to a local construction company.;Second, the previously developed framework was further validated and applied to a residential development project in Saudi Arabia. The construction sector has been growing rapidly in Saudi Arabia; however, the quality of Saudi Arabian construction is decreasing, resulting in excess waste generation and associated environmental impacts. This case study examined a project with 53 residential units overall but only 10 units acceptable at final inspection. The largest quality issue was determined to be exterior paint blistering. Using the developed framework, defective units were investigated through a field examination, narrowing down the causes of the blistering applying the Pareto method as follows: Inadequate method, untrained workers, weather, and others. Next, the Process improvement tool was applied to reduce the blistering causes and to improve the current process. A new method was designed and applied to a separate residential unit for validation. The modified method showed a great improvement and in the end the unit was able to pass inspection.;Finally, building on the previous case studies, the framework was later refined with the goal of applying it earlier in a project, prior to construction, to further reduce potential waste generation and associated environmental impacts. Using Lean Green, and Six-Sigma (LG6) and adopting the same improvement model, DMAIC, the owner can evaluate all steps separately in the process, addressing all resources consumed and analyzing environmental impacts which might be generated; this highlights potential waste and so can help the owner avoid waste occurrence by indicating where the process needs to be amended to create less environmental impact and more efficiency. For this research, the model was used to help evaluate the construction process for the installation of 160 woodpiles. The model identified that four steps out of eight were considered as non-adding value steps or waste. Three steps out of four non-adding value steps were involved with mobilization and demobilization of the equipment. The remaining wasteful step was cutting to length all installed woodpiles. The model showed that if these steps were replaced, eliminated or planned well, environmental impacts would be reduced by 9%.