When an interlocking is used as one of the limits of a temporary speed restriction, when does the speed restriction begin?

The correct answer indicates that a temporary speed restriction (TSR) begins only after it is explicitly stated in Form D or the TSR Bulletin (TSRB). This is crucial for maintaining clarity and safety among train operations. By enforcing that the speed restriction is formally documented and conveyed through official communication methods, it ensures that all relevant personnel are aware of the change in speed limits. This practice helps to prevent confusion and promotes adherence to the defined operating conditions, which is vital for the safety of train movements.

Some might think that the speed restriction could begin at the beginning of or within the interlocking area. However, without a formal announcement in the proper documentation, those points along the interlocking do not indicate a valid starting point for the restriction. Similarly, other options that suggest a location-based initiation of the speed restriction lack the necessary procedural backing that must accompany such restrictions. This emphasizes the regulatory framework that governs train operations, prioritizing communication and compliance with established procedures for speed management.