Stray currents, mostly known for their detrimental corrosion affects on the underground structures, can be effectively controlled by the implementation of specific measures at both the source of generation and at the affected structure(s). This paper discusses the most serious sources of stray current generation, the resulting problems and the
numerous control methods that can be utilized to minimize corrosion and safety problems. Safety concerns associated with dc power systems are also discussed. Keywords: Stray currents, transit systems, stray current corrosion, rail bonds, cathodic protection, drain bonds, reverse current switches, HVDC