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Railroad Signal Systems

Electromagnetic Effects on Railroad Signal Systems

Over the last several years, railroad signal systems have migrated from electromechanical systems to microprocessor based systems. As a result, the signal systems have become more susceptible to electromagnetic effects, including lightning strikes and power line induction.

Since 1997, EMA has been involved in intense efforts to provide electromagnetic effects protection for railroad signal systems, including both wayside, hump yard and dispatch center applications. The extensive EME experience and background EMA brings from the Aerospace and Military environments has proven to provide comprehensive protection for railroad signal systems, which must provide highly reliable train control.

Lightning Protection of Railroad Signal Systems

Wayside Lightning Protection

EMA has extensive wayside experience and a thorough knowledge of signal system architecture and installations and how they can interact with lightning.

EMA has done extensive field surveys of wayside installations, including crossings, radio code, defect detectors, electronically coded track circuits, pole lines, movable bridges, etc., on installations in both the USA and Canada. Based on these surveys, EMA has identified the equipment, wiring practice, and installation issues affecting the lightning vulnerability of these systems.

EMA has then developed a comprehensive lightning protection approach, based on faraday cage shielding, cable shielding, improved wiring practices, and the fielding of a newly designed low voltage arrester for track circuits, signals, etc. This approach has been formally implemented on a large scale on some of the largest Class V railroads in the United States.

The approach is completely implemented for new wayside applications, but EMA has also developed retrofit methods for improving the protection level of legacy installations. EMA has published a paper summarizing this approach in the 1999 AREMA conference proceedings.

Hump Yard Lightning Protection

EMA has performed lightning protection audits and surveys of many hump yards in the USA and in Canada. As a result, EMA is very familiar with hump yard process control and the related lightning protection issues.

EMA has worked with one of the largest Class V railroads in the USA to provide a comprehensive lightning protection approach based on the proven concepts of faraday cage shielding, cable shielding, terminal protection, fiber optics, and improved wiring practices. This approach has been implemented on several recent upgrades of hump yard Process Control Systems (PCS), providing highly reliable operation in severe lightning environments.

Dispatch Center Lightning Protection

EMA has also performed lightning protection audits and surveys of many dispatch centers in the USA and in Canada. As a result, EMA is very familiar with dispatching functions and the related lightning protection issues.

EMA has worked with one of the largest Class V railroads in the USA to provide a comprehensive lightning protection approach based on the proven concepts of faraday cage shielding, cable shielding, terminal protection, fiber optics, and improved wiring practices. This approach has been implemented on some major dispatch centers to provide significant improvements in operations reliability.

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