What must happen if a signal does not display a proceed indication after the switch is opened?

The correct action when a signal does not display a proceed indication after the switch is opened is to move the train at restricted speed. This is a significant safety measure in railroad operations. Restricted speed allows the train crew to operate at a speed that can enable them to stop within half the range of vision, ensuring that they can respond to any potential hazards or obstacles on the track.

When a signal does not show a proceed indication, it indicates a stop or caution. The requirement to move at restricted speed means the crew must remain vigilant and prepared for any emergency situations arising from the signaling or track conditions. This helps maintain safety while still allowing the train to continue its journey under controlled circumstances.

The other options present actions that either do not align with established safety protocols or are impractical. Waiting indefinitely does not address the need to move safely and could lead to further complications. Contacting the control operator may be necessary in certain scenarios, but it does not directly resolve the immediate need to proceed with caution. Continuing to move regardless of the signal would be detrimental to safety and violate operating rules.