What is a Positive Train Control System (PTC)?

A Positive Train Control System (PTC) is defined as an electronic train control system that enforces various operational conditions, making safety and efficiency of train operations its primary goals. PTC systems are designed to prevent certain types of accidents, such as collisions between trains, derailments due to excessive speed, and unauthorized movements onto track segments that are out of service.

The system utilizes GPS, wireless communications, and onboard computers to monitor train movements and enforce compliance with speed limits and other operational protocols. For instance, if a train exceeds a predetermined speed limit, the PTC can automatically take control, slowing the train down to ensure safety.

While other choices mention systems that may be involved in train operations, they do not encompass the full capabilities or objectives of a Positive Train Control System. Manual signal control systems do not offer the same level of automation and safety assurance that PTC provides, and backup systems or advisory systems lack the proactive enforcement features that characterize PTC. Thus, option A accurately describes the comprehensive role and functionality of a Positive Train Control System.