Transmission Line, Railroad and Pipeline Common Corridor Study

The sharing of common corridors by electric power transmission lines, pipelines and rail-road facilities is becoming more commonplace. However, such corridor sharing can result in undesired coupling of electromagnetic energy from the power lines to the paralleling facilities. The principal concerns are with respect to both personnel safety and equipment operational compatibility. Induced interfering voltages and currents can result from either magnetic or electrostatic induction from the power line circuits. The induction can occur during either the normal steady-state operation of the power system or during a fault. The situations that give rise to problems, as well as the candidate mitigation measures, depend on the susceptibilities, the excitation parameters and the interaction between the electromagnetically coupled components of the common corridor. This paper presents the results of a recently completed study of a utility common corridor in southern Arizona. A detailed analysis of the voltages and currents induced into the pipeline and rail facilities was performed using a computer program developed during the study. Alternate forms of mitigation were investigated to ensure personnel safety and operational compatibility where likely problems were predicted.