According to operating rules, yellow-red flags must be displayed how many miles before the restricted area?

The correct answer indicates that yellow-red flags must be displayed two miles before the restricted area. This practice is crucial for ensuring the safety of both the train and the crew, as it provides adequate warning to prepare for a change in operations or condition ahead. Displaying the flags at this distance allows train operators to decelerate and approach the restricted area with caution, helping to prevent accidents or mishaps that could occur without proper notification.

The two-mile warning is consistent with safety protocols designed to allow sufficient time for the crew to react to the upcoming restrictions, whereas shorter distances might not provide enough time to appropriately slow down or prepare for what lies ahead.