What is a warning sign that indicates a railway crossing is ahead?

The warning sign indicating a railway crossing is ahead is characterized as a circular sign featuring a black "X" and the letters "R" on each side. This design is standardized to alert drivers to the presence of an upcoming railroad crossing, thereby urging them to approach with caution. The “X” symbolizes a crossing, and the "R" indicates "railroad," making this sign easily recognizable for its specific purpose.

These elements are crucial for ensuring that drivers are adequately warned of the potential for train traffic, allowing them to slow down, look for oncoming trains, and ensure it is safe to proceed. Recognizing this sign is essential for safety, as it helps prevent accidents at railway crossings where trains may come unexpectedly.