What is the maximum speed for trains operating under Form D line 563?

The maximum speed of 49 mph for freight trains operating under Form D line 563 is established based on safety parameters and regulations set forth by the governing railway authority. This limit is designed to ensure that freight operations maintain a consistent and safe pace while navigating the rail network, taking into consideration the weight of the trains, track conditions, and the types of cargo being transported. This speed ensures that freight trains can operate efficiently while reducing the risk of incidents or accidents.

The various speed limits provided in the other options reflect the different operational contexts for passenger and freight trains. However, for freight services under specific directives like Form D line 563, the 49 mph limit is appropriate for maintaining safety without sacrificing service efficiency.