Stray current is a major concern for the track utility and infrastructure owners in the vicinity of thedirect current (dc) powered rail transit system.Stray current leakage and the corrosion caused by these currents is more of an issue in low resistivity soils and embedded tracks which typically run through major traffic areas city centers and tread between utility lines that require the rail to be continuously isolated to provide superior track-to-earth resistance.The absence of specific national stray current control and/or mitigation standard or guideline in the U.S necessitates the need to produce contemporary standards and guiding principles for the transit providers and corrosion consultants to match the advancements made in other sectors of the rail transit system. The author thus prepared a guidebook for the Transit Cooperative Research Program (TCRP) documenting best practices for those seeking guidance on design maintenance and testing of stray current control for dc powered rail transit systems. The guidebook is a resource that can be put into use immediately by stray current corrosion consultants transit agency owners and corrosion testing and maintenance providers.This guidebook includes the study of both national and international transit agencies. It is formatted as a reference guide to provide a user-friendly framework of consolidated guidelines and recommendations that will help in mitigating and/or eliminating stray current leakage from dc operated rail tracks using the data collected from transit agency and corrosion consultant interviews stray current corrosion survey questionnaires and field testing of a mix of 30 transit agencies (21 national and 9 international).This paper discusses “Lessons Learned” on the problems of surveying the transit industry how they were overcome and the results of a case study on issues related to stray current effects from one of the transit agencies that were used in preparing these consolidated guidelines and recommendations.
Stray current refers to electric current that flows elsewhere rather than along its intended path. Stray current is a well-known factor in pipeline maintenance and has been discovered to be an important consideration in communication and electric transmission structure maintenance. Corrosion caused by stray current is frequently many magnitudes greater than corrosion that occurs naturally in soil. Stray current may accelerate corrosion on guy anchors of communication towers and electric transmission towers which could lead to reduced service life or catastrophic failure.
In this paper, stray current corrosion risk for galvanized guy anchors is discussed in detail. Identification by structure-to-soil potential measurements is discussed. Stray current case studies are presented. Overall, this paper demonstrates that while stray current corrosion is a significant risk for guyed telecommunication and electric power structures, it can be detected and mitigated. This paper is an overview of the commonly accepted practices of stray current detection and mitigation used today.