How far behind a derail in the derailing position must you stop?

• A. 50 feet
• B. 150 feet
• C. 200 feet
• D. 100 feet

Answer: (D)

The main idea is keeping a safe stopping distance behind a derail that’s in the derailing position. A derail is set to intentionally derail equipment to protect against a collision, and when it’s in that active position there’s a risk of unexpected movement, debris, or the derail mechanism itself. To reduce the chance of being struck or fouling the track, you must stop far enough back to have time to react and to stay out of the derail’s zone.

100 feet is the standard minimum distance prescribed. It gives you enough space to see what’s happening, brake safely, and move if needed, while staying clear of any potential movement of a derailed car or the derail equipment. Stopping only 50 feet away would leave insufficient clearance and reaction time. Stopping much farther than 100 feet isn’t the mandated distance, even though it would be safe; the rule specifies 100 feet.