What is the maximum speed with a single unit locomotive without cars attached?

The maximum speed with a single unit locomotive without cars attached is indeed 30 mph. This speed limit is established to ensure safety and operational efficiency when a locomotive operates independently, without the additional weight and drag of cars.

Operating at this speed allows for better handling of the locomotive, reducing the risk of accidents or derailments, particularly when negotiating curves or transitions in the track. The restriction is a part of standard operating procedures within rail operations, aimed at maintaining control over the equipment. It reflects considerations such as the locomotive's braking capabilities and the need to respond promptly to any unexpected situations on the track.

Choosing this speed demonstrates an understanding of the balance between performance and safety protocols in rail operations, emphasizing the importance of adhering to established speed limits for locomotives based on their operational context.