What speed must a train moving past a Stop signal authorized to proceed maintain?

A train movement past a Stop signal must maintain restricted speed to ensure safety and compliance with operational protocols. Restricted speed allows a train to react appropriately to any potential obstacles, track conditions, or signal changes that may be present in the area beyond the Stop signal. It typically means the train should be prepared to stop within half the range of vision, which is crucial in maintaining safety on the railway.

Operating at restricted speed reduces the risk of accidents as it provides the engineer more control and time to assess the situation ahead. This standard is in place to ensure that the crew is vigilant and ready to respond to any unexpected hazards.

In contrast, full speed would be inappropriate as it does not take into account the safety measures needed when proceeding past a Stop signal. Slow speed might suggest a greater level of caution than required, while stating no specific speed would not ensure adherence to safety protocols necessary in this scenario. Thus, maintaining restricted speed is the most appropriate and safe action when a train approaches a Stop signal authorized to proceed.