Rail transportation systems are particularly prone to lightningand electrical damage. The many interconnected wayside systems areenvironmentally exposed and geographically distributed. Physicalseparation and the necessary interconnecting cables make the varioussignal, communications and power systems prime targets for damage fromground potential differences. The MTA Long Island Rail Road (LIRR)provides an excellent case study for this subject. As the largestcommuter railroad in the US, the LIRR has a very high density ofelectrical and electronic equipment located along its right-of-way.Although the incidence of lightning on Long Island is relativelymoderate, earth ground disturbances are of a much higher magnitude, dueto extremely poor soil conductivity. To address these issues, the LIRREngineering Department formed a multi-disciplinary task force. Theirinvestigations revealed that equipment damage had been incorrectlyattributed to either lightning or DC traction power faults.Investigations showed the main cause was actually AC transmission anddistribution line power faults, due to a lack of inductive coordination.This paper provides some background information on lightning, powerfaults, and ground potential differences, and summarizes the Railroad'sexperience since it began seriously addressing these problems sevenyears ago
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