Which of the following is NOT included as self-propelled equipment in on track safety guidelines?

Self-propelled equipment refers to vehicles or machines that can move themselves independently on the rail track. In this context, the options that are typically classified as self-propelled equipment—such as hi-rail vehicles, automated inspection cars, and rail-bound vehicles engaged in inspection—are all designed to operate on railway tracks and possess their own propulsion systems.

Excavators, while they may be used in maintenance or construction work that occurs near or on the tracks, do not typically have the capability to independently travel along the rails like the other options mentioned. Instead, they are usually mobile construction equipment that requires transport to and from job sites. They lack the specialized adaptations that allow them to operate as rail vehicles, such as rail wheels or track guidance systems.

Therefore, excavators used on tracks stand apart from the other options because they do not fall under the category of self-propelled rail-bound equipment as defined by on-track safety guidelines. This distinction is essential for maintaining safety standards and operational protocols on the railways.