What type of speed may a block operator allow for another train entering a block?

A block operator may allow for restricted speed for another train entering a block in order to ensure safety. Restricted speed is defined as the speed at which a train can stop short of a signal, a switch, or an obstruction. This is a crucial consideration for preventing accidents, particularly when a train is entering a block where another train may be present.

By allowing only restricted speed, the operator ensures that the incoming train can respond to any unforeseen circumstances, such as a train occupying a section of track unexpectedly or equipment failures. The restricted speed allows for the necessary precautions to be taken, emphasizing safety and adherence to operational protocols.

Normal speed would not account for the need to stop for potential hazards, and high speed for emergencies contradicts the principles of caution and safety during typical operational circumstances. Variable speed based on conditions may introduce ambiguity and unpredictability, which can jeopardize the safety of train operations. Therefore, restricted speed is the most appropriate choice to ensure a controlled and safe entry for trains into a block.