Catenary maintenance vehicle

A catenary maintenance vehicle (also known as a tower wagon or tower car) is a railroad maintenance of way vehicle that is used to maintain and inspect overhead line (also known as catenary) on electrified railroad or metro tracks. Such vehicles are typically self-propelled by a diesel engine, to allow them to operate when power is shut off to the overhead lines for worker safety or in the event of a power failure.

Source: Wikipedia — Catenary maintenance vehicle (CC BY-SA 4.0)