Date of Award


Document Type


Degree Name

Master of Science (MS)

Legacy Department

Civil Engineering

Committee Member

Dr. Kaylan R. Piralta, Committee Chair

Committee Member

Dr. Leidy Klotz, Co-Chair

Committee Member

Dr. Kapil Chalil Madathil


Traditional underground utility construction and rehabilitation methods entail cutting open the ground which not only disrupts traffic causing delays and inconvenience, but also damages surface-based vegetation in some areas. Additionally, underground infrastructure density has been growing thereby making it more challenging to employ the traditional open-cut construction method. A sustainable alternative is the use of trenchless construction methods where underground infrastructure is installed or repaired with minimal surface disruption. Horizontal Directional Drilling (HDD) is one of the popular trenchless methods for installing buried utility pipelines. Risk dimensionality and severity is generally greater in the case of HDD projects because of the fact that only limited soil and other sub-surface sampling will be done to choose the right type equipment, labor, materials, and drilling plan. Some of these risks have led to accidents on HDD projects in the past that not only damaged the equipment and other infrastructures, but also injured workers which proved fatal in some cases. In order to minimize the safety risk in HDD projects, there is an outstanding need for the investigation of hazards, factors and project characteristics that propel the probability of occurrence of accidents. This thesis report presents the development and demonstration of the hierarchical safety risk assessment framework for investigating the safety risk, especially the probabilities of occurrence of various hazards, of HDD projects. The developed “Hierarchical Risk Assessment” framework is demonstrated using two real-world HDD projects. The safety risk analysis performed on the two case studies highlighted the factors and project characteristics that aggravate the hazards and their probabilities of occurrence. The proposed approach for investigating safety risk on HDD projects needs to be further investigated and extensively evaluated on more real-world case studies before it can be developed into an adoptable tool for practice.



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