Define Positive Train Control (PTC) and name two safety outcomes it mitigates.

• A. A safety system that automatically enforces speed limits, movement authorities, and enforced stops to prevent train collisions and overspeed derailments.
• B. PTC is a system for maintaining track geometry and signaling redundancy.
• C. PTC is a manual process for dispatchers to authorize track usage.
• D. PTC is a passenger information system displaying upcoming stations.

Answer: (B)

Positive Train Control is a safety system that automatically enforces essential operating limits—specifically speed limits and movement authorities—and can apply automatic stops when a train is at risk of violating those limits. This real-time enforcement helps prevent two major hazards: train-to-train collisions and overspeed derailments, especially in areas with complex routing or temporary restrictions.

The other descriptions miss what PTC actually does: it isn’t about maintaining track geometry or signaling redundancy, it isn’t a manual dispatch process, and it isn’t a passenger information system.