Keywords: underground pipelines, pipeline safety, evaluation model, risk assessment, pipeline protection, construction operation.

Construction operations are always threatened by unforeseen events and uncertainties that take place throughout the course of the lifecycle of any project. Some of these uncertainties can be measured, controlled, and prevented. At the same time some of these uncertainties are unpredictable and can not be easily prevented no matter how well contractors prepare. One of these uncertainties or unforeseen events is introduced early in the lifecycle of the project. These events involve the excavation activities of the project.

Excavation might not be a very complicated task to perform, but it could develop into a very hazardous and dangerous task to accomplish. Aside from the hazardous substances that might be encountered in the ground, risk and unforeseen accidents are inherent in every construction project. With every shovel, hoe or pile driver movement, the unforeseen event of damaging the underground utility pipelines increases.

While utility pipelines lie safely underground, undisturbed by weather conditions, they cannot be protected from other damages induced over them by construction operations. Damage to pipelines usually occurs due to the lack of knowledge of the exact location of the pipes. The effects of the damages to the pipelines do not only impact the contractor, but it also has great impact on the public, local government, and businesses as well. These impacts include but are not limited to the disturbance of the supply of essential services like water, gas, telecommunications, electricity, and other services. Additionally, direct and indirect costs are involved in these damages.

The process of excavating and laying pipelines, in addition to excavating near pipelines involves many parties. These parties include city planners, utility providers, site owners, contractors, designers, construction managers, construction workers and machine operators. All mentioned parties are directly or indirectly involved in protecting, as well as damaging the utilities pipelines. They are also involved in securing and exact locating of any new utility pipelines. It is true that new technologies and sophisticated devices exist to take care of locating these pipelines, but preventative measures are always a desired quality that should be utilized. Moreover these devices are somewhat limited in their capabilities and sometimes cannot precisely determine the depth of the pipes [1].

The purpose of this work is to develop a systematic approach using software that can be utilized to minimize or prevent damages to gas pipelines through the assessment of risks involved in working near gas pipelines or digging around these pipelines. Some of the factors that are considered are the accuracy of the location of the pipes, the necessity of digging near the pipes, and the existence of any warning system which helps in minimizing the damages.

These risks are assessed systematically through a number of questions, qualitative evaluation, and fault tree analysis to evaluate the risks involved in carrying out the excavation in the proximity of the gas pipelines, and the possibility of incurring any damages. The software evaluates cases individually through qualitative measures, and fault tree analysis. The software also suggests strategies to minimize the risk associated with excavating near the gas underground pipelines.

1

Bernold, L.E., "Economic Model to Optimize Underground Utility Protection", Journal of Construction Engineering and Management, November/December 2003. doi:10.1061/(ASCE)0733-9364(2003)129:6(645)

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