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March 20, 2026|Safety

NTSB Issues ‘Rail Propulsion Power Systems’ Safety Alert

Written by Marybeth Luczak, Executive Editor
The National Transportation Safety Board (NTSB) on March 19 published Safety Alert No. SA-105, “Electric Propulsion Power Systems – Finding Risks in Aging Rail Infrastructure,” for transit and commuter rail operators. It provides five steps that agencies can take to manage systems and help “avoid critical failures.”

The Problem

“As the nation’s rail infrastructure ages, transit and commuter operators are experiencing critical failures related to electric propulsion power systems, putting the traveling public at risk,” the NTSB reported. “Our investigators have observed electrical arcing, fire hazards, and smoke incidents from critical failures of electric propulsion power systems that have endangered passengers and employees.”

It provided the following examples:

  • “Flooding or drainage issues can expose electrical cables to water intrusion and cause cable insulation to degrade.
  • “Worn contact surfaces on electrified third rails, collector shoes, or pantograph heads may cause intermittent contact, which can lead to arcing.
  • “Loose or corroded electrical connectors and joints on catenary wire or third-rail systems can increase electrical resistance, which can generate excessive heat in electrical components and lead to fires, electrical shorts, or other dangers.”

According to the NTSB, recent investigations have found some electric propulsion power systems—such as third-rail systems or overhead wire catenary systems—“have merged newer technologies with legacy components, introducing new failure modes.” It noted that “[t]emporary repairs and undocumented changes to third-rail or catenary systems, as well as aging electrical component tolerances that drift over time from their original design performance criteria, can also cause critical electrical problems.” These, it said, include arcing caused by worn contact surfaces, fires resulting from degraded cable insulation, and overheating from loose or corroded electrical connectors that increase resistance. “These critical failures may not be adequately detected or mitigated by transit and commuter rail operators’ existing maintenance and inspection plans,” the NTSB reported.

Next Steps

The NTSB provided the following five actions that transit agencies can take:

  1. “Implement reliability engineering processes. If these processes are already in place, use them to reassess safety analyses of the design of electric propulsion power systems and other critical systems, particularly as equipment ages and when temporary repairs and changes are made to third-rail or catenary systems.
  2. “Ensure all measurable hazards—including those involving aging electrical infrastructure or newly introduced replacement components—are incorporated into system safety programs like safety management systems (SMS). An SMS can provide structured processes to evaluate new or modified components for potential failure modes, integrate components safely with legacy systems, and monitor the components over time so emerging risks are identified early and mitigated effectively.
  3. “Be aware of electric propulsion power system failures that involve aging electrical components. Review your maintenance, testing, and inspection procedures for wayside, car-borne, and associated electrical system components. Address deficiencies identified in the review.
  4. “Use system failure modes identified in records or in previous incidents to review and revise—or develop, if necessary—maintenance, inspection, and testing procedures that can detect or prevent these failures.
  5. “Use technology to generate real-time trend reports so emerging safety issues can be identified early and risks can be mitigated.”

The NTSB also provided access to these related investigations: