What is a Derail?

• A. A device used to block a train from leaving a yard.
• B. A track safety device, designed to guide a car off the rails at a selected spot as a means of protection against collisions or other accidents.
• C. A signal indicating a derail event.
• D. A switch that cannot be operated.

Answer: (B)

A derail is a track safety device designed to guide a railcar off the rails at a designated spot as a protection against collisions or other accidents. By directing a car to leave the main track at a controlled location, it prevents runaway cars from causing damage or injuries on other tracks or equipment. It’s a proactive safety tool used especially in yards, sidings, or at danger points.

This isn’t simply a mechanism to block a train from leaving a yard, nor is it a signal indicating a derailment event. It isn’t a switch that cannot be operated. The core idea is its function: to deliberately derail a car at a safe location to prevent greater danger.