A Case Study of Railway Track’s Gradient Control Wire Corrosion Assessment – Phase I

Abstract This paper presents a corrosion threat assessment of the gradient control wire (GCW) installed along a diesel-powered railroad track system in Connecticut, USA. Field investigations were conducted to determine the root cause of accelerated corrosion and assess the influence of stray direct current (DC) interference, alternating current (AC) potentials, and soil corrosivity. Testing included DC and AC potential data logging, soil resistivity measurements using the Wenner four-pin method, laboratory soil corrosivity analyses, and a close interval survey (CIS) along a 1448 m GCW section. Results indicate DC stray current interference suspected from an unidentified DC source, with AC potentials observed below safety thresholds. Soil samples exhibited mildly corrosive characteristics with localized microbiologically influenced corrosion factors. Recommendations are provided for further diagnostic testing, cathodic protection verification, and system modifications to mitigate long-term corrosion risks.