ACCELERATED WASTEWATER PIPELINE CONSTRUCTION

Date of Award

8-23-2024

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Civil and Environmental Engineering

Advisor(s)

Baris Salman

Subject Categories

Civil and Environmental Engineering | Civil Engineering | Engineering

Abstract

ABSTRACT Traditional construction and contracting approaches to wastewater pipelines construction projects have proven to be ineffective in reducing construction problems. Construction industry currently suffers from troubling inefficiencies that produce lengthy delays. Delays affect commuters, local businesses, project cost, environment, and the public and worker’s safety. Therefore, new construction technologies and innovative contracting approaches are needed to address the current inefficiencies and delays, while also working towards minimizing the effects of construction. The Kingdom of Saudi Arabia (KSA), one of the fast-growing economies in the last decade, invested $135 billion into modernizing its infrastructure, which includes the expansion and rehabilitation of its wastewater pipelines networks. Saudi Arabia’s traditional construction techniques, such as open-cut, and contracting methods, such as design-bid-build, in wastewater pipeline construction projects have proven to be ineffective at reducing current construction problems. The adoption of accelerated wastewater pipelines construction (AWPC) techniques and innovative contracting strategies are needed to address the current inefficiencies through reducing construction delays, costs, and construction-related consequences. The United States and other developed countries have led the way in innovating and improving construction techniques within the industry. However, the Kingdom of Saudi Arabia (KSA) presents its own unique set of characteristics and challenges in the construction sector. To gain a comprehensive understanding of these distinct issues, this study employed a multifaceted approach. The research methodology included an extensive literature review, carefully designed questionnaire surveys, and interviews with industry professionals. This comprehensive approach aimed to uncover the nuances of construction challenges specific to the KSA context. Based on the survey data, a decision-support platform is designed that may help key stakeholders adopt appropriate construction and contracting strategies to address Saudi Arabia’s current problems and accelerate wastewater pipeline construction projects. Part I of the first questionnaire survey focused on factors that may cause delays in wastewater pipeline construction projects. 110 respondents from 16 Saudi cities participated in this survey. These respondents have experience in wastewater pipelines construction ranging from 15 to 25+ years. The analysis of data encompassed calculations of relative importance index (RII), rank agreement factor (RAF), and the extent of consensus or divergence between two groups. The overall RII varied between 0.722 to 0.456 for the most significant factor of labor supply to weather conditions. The top ten ranks for the delay causes were labor supply, equipment availability and failure, unforeseen ground conditions, labor productivity, improper planning, obtaining permits, conflicts and overlaps with infrastructure facilities and other regulatory bodies, availability of money for long construction period (budget constraints), change orders, mistakes made during the construction stage, and inadequate contractor experience. The second part (part II) of the first questionnaire aimed at assessing the present implementation status in AWPC projects in the KSA and targeted only the practitioners who have used AWPC for their projects within the last five years of survey date (2013-2018). 49 out of total 110 practitioners who participated in the first survey (part I) from four Saudi cities have adopted AWPC for their projects in the last five years (2013-2018) and they completed the second part (part II) of the first questionnaire survey. The percentage of AWPC projects was very low and ranged between 14 and 24 with an average of 19.5%. Among projects with the AWPC, a higher percentage of projects utilized Microtunneling over other AWPC techniques. In addition, the survey results revealed high success rates for Accelerated Wastewater Pipeline Construction (AWPC) projects, with 84% completed ahead of schedule and 81% finished within budget constraints; whereas, percentage of projects with acceptable quality and free from accidents were 91% and 93%, respectively. Furthermore, the survey indicated that 60% of the implemented projects using AWPC techniques were planned projects, whereas, 40% were triggered by emergency circumstances. Initial cost was the most important criterion while deciding to undertake AWPC projects. Among social and environmental parameters, safety and noise pollution were the most prioritized parameters, respectively. The survey data also indicates that in all the projects traditional contracting method of Design-Bid-Build (DBB) was adopted. In addition, a decision-support framework consisting of a flowchart and an AHP model to select the appropriate construction alternative is presented. The developed flexible decision support system platform can only be used as a tool to select an appropriate accelerated construction technology(s), as design-bid-build (DBB) is the only delivery method that is employed in wastewater pipeline construction projects in the KSA. The upper level of the developed decision support flowchart includes the unique trenchless criteria followed by technical, social, and environmental considerations, and economic attractiveness. If the unique trenchless criteria fail to assign just one candidate alternative, the decision-makers can proceed along the flowchart to the technical, social, environmental, and economic aspects; otherwise, the final decision can be made by selecting the appropriate alternative. If no one alternative clearly outscores others when evaluated for these technical, social, environmental, and economic aspects, the decision-maker should proceed to the proposed decision-making model to select the appropriate construction option. The decision-making model should be used not only when the flowchart fails to narrow down the alternatives to a single option, but also when the open-cut method is one of the options. For this purpose, an Analytical Hierarchy Process (AHP)-based decision-making model was developed to evaluate construction alternatives. The model included four main criteria and sixteen sub-criteria that affect the decision-making process. Weights for four main (level 1) criteria (i.e., economic, environmental, social, and technical) and sixteen sub-criteria (level 2) were obtained through a questionnaire survey. The AHP model revealed a clear hierarchy in the importance of criteria for selecting the optimal construction alternative. Economy emerged as the dominant factor, commanding a priority score of 56.7%. Within the economic criterion, initial cost stood out as the most crucial sub-criterion, receiving the highest priority vector value. This underscores the primacy of financial considerations in the decision-making process. In contrast, the other main criteria - environmental, social, and technical - received significantly lower priority scores of 11.7%, 11.7%, and 19.9% respectively. This distribution of weights indicates that while these factors are considered in the selection process, they are substantially outweighed by economic considerations, particularly the initial cost, when determining the most suitable construction alternative. Fourteen case studies were conducted to evaluate and justify the best alternatives. Ten cases demonstrate that the best alternative for accelerating wastewater pipeline construction activities is a trenchless technology alternative, while the remaining four cases justify the use of the traditional open-cut method. Additionally, with the exception of five cases, the AHP model's conclusions were consistent with the construction technique utilized in the case studies. Furthermore, a sensitivity analysis was carried out under five simulated scenarios. The analysis demonstrated that the AHP model is robust and stable. Finally, the AHP model and the two decision support flowcharts were validated and justified based on expert judgment. The developed AHP and the decision support flowchart to select the appropriate construction alternative were validated. In addition, a flowchart to select the appropriate delivery method, which was developed through a literature review process, was presented and included in the validation process to enhance the comprehensiveness of the study and to serve as a reference for future studies.

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