How do crew members proceed if a yellow-red flag is displayed without specified restrictions?

When a yellow-red flag is displayed without specified restrictions, crew members should proceed at a restricted speed. The yellow-red flag signals that there may be a condition that warrants caution, but without clear instructions, it's important to prioritize safety. Restricted speed allows the crew to maintain control of the train while being prepared to stop if necessary, ensuring they can respond to any unforeseen situations or obstacles that may arise on the track. This approach aligns with established safety protocols, which emphasize the importance of being vigilant and cautious when facing ambiguous signals.