What could be classified as a specific defect under FRA regulations?

A worn frog with a broken bolt is classified as a specific defect under FRA regulations because it directly affects the functionality and safety of the track infrastructure. Frogs are critical components of rail design that allow trains to switch tracks, and any wear or malfunction, such as a broken bolt, can lead to serious operational hazards, including derailments or train delays.

The focus on specific defects is essential in ensuring safety and compliance with regulatory standards. While other options may indicate concerns about track integrity or maintenance issues—such as a bend in a track rail, excess vegetation, or rust on a rail joint—these do not pertain to a singular, immediate failure or compromise in safety that can be linked as directly to a specific component's operation. Thus, identifying and addressing a worn frog with a broken bolt stands out as a critical maintenance issue that requires prompt attention.