Flashing red lights are operating at a railroad grade crossing. What must you do?
Correct answer: A – Stop 15 to 50 feet from the nearest rail and proceed only when safe
In North Carolina, an electrical or mechanical signal warning of an approaching train or on-track equipment requires a stop between 15 and 50 feet from the nearest rail. Do not proceed until the crossing can be made safely. Never drive through, around, or under a gate while it is closed or moving.
Source: N.C. Gen. Stat. § 20-142.1(a)(1), (b) – Obedience to railroad signal


