An overview is presented on the historical aspects of stray currents created by dc-powered transit system operations and their control. The relatively recent resurgence in the interest and the construction of dc-powered transit systems has emphasized the necessity forcontrol of stray currents. This is particularly significant for newsystems being built in areas where the utilities and other facilities were not designed with consideration for the need for stray current control measures. The theoretical aspects of the reasons for stray currents and the methods available for their control are presentedalong with practical applications within new and old systems as part of revitalization programs. The results obtained have shown that stray current control is practical. Although certain aspects of straycurrent control are common within all dc-powered transit systems, the variations within the transit systems and the areas they serve require that systems be treated individually to determine the level ofstray current control required and the best means of achieving thislevel. This paper appeared in transportation research record no. 1152, rail rapid transit and planning tools. For covering abstract seeirrd no 818412.
Abstract