A sign shows a railroad crossing symbol — a round yellow sign with a large X and 'RR' — 300 feet before train tracks. What is the required driver action?

RAILROAD CROSSING ADVANCE WARNING SIGN: The ROUND YELLOW SIGN is unique to railroad crossings — the only round yellow sign in the US road sign system. It appears 250-600 feet before the crossing. DRIVER REQUIREMENTS: Slow down; LOOK in BOTH directions (trains approach silently at distance); LISTEN (turn off music, lower windows); Be prepared to STOP; DO NOT STOP ON THE TRACKS — stop before the nearest rail or stop line (15-50 feet from the track); If stopped traffic might push you onto tracks: do not enter the crossing until you can clear it completely; Never race around lowering gates; Never go around raised gates that haven't started — additional trains may come from either direction; PAVEMENT MARKINGS: 'RR' and X painted on road surface appear before the crossing; white stop line at the required stop position.