LIGHT RAIL STRAY CURRENT
LONG TERM DATA LOGGING
The effects of stray currents produced by DC powered Light Rail Transit (LRT) systems on nearby underground pipelines have been studied extensively due to significant interference and pipeline failures associated with stray currents. Determining which pipelines are at an increased risk for stray current corrosion is commonly evaluated by measuring “snapshots” of pipe-to-soil potentials and comparing values to established cathodic protection criteria. Due to the dynamic nature of LRT systems, the value of this data is limited because it does not provide a long-term representation of pipeline conditions.
The need to monitor pipe-to-soil potentials for longer durations became apparent when discrepancies in the pipe-to-soil potentials were observed. Variations in the data have been attributed to seasonal weather changes, LRT maintenance, LRT system operations, and pipeline operations.
Continuous, long-term pipe-to-soil potential data logging on utilities near the LRT system has provided valuable information in identifying environmental and operational factors that influence stray current activity on the nearby pipelines.
Information is presented on field data collection and management, data correlation, data analysis, and future considerations for stray current monitoring. The information can be used to determine the need for mitigation, develop mitigation strategies, and assess the amount of time pipe-to-soil potentials are outside utility owner standards for corrosion control.