What is the purpose of guard rail mounted to the inside of running rails?

What is the purpose of guard rail mounted to the inside of running rails?

• A. To guide signals.
• B. To keep wheels in-line with the track in the event of a derailment.
• C. To provide clearance for maintenance equipment.
• D. To reduce track noise.

Answer: (B)

Guard rails, also called check rails, inside the running rail are placed to keep wheelsets aligned and to guide wheels back onto the proper rail if a derailment or wheel climb starts. On curves or near switches, a wheel flange can catch and ride up, pushing the wheel away from the intended path. The guard rail provides a hard boundary that the wheel can be guided against, helping the wheel stay in line with the track and return to the running surface instead of leaving the rails. This is what prevents derailment and maintains straight, safe guidance of the train. Other options don’t fit this purpose: signals aren’t guided by guard rails, guard rails aren’t primarily for clearance for maintenance equipment, and they aren’t used to reduce track noise.

Guard rails, also called check rails, inside the running rail are placed to keep wheelsets aligned and to guide wheels back onto the proper rail if a derailment or wheel climb starts. On curves or near switches, a wheel flange can catch and ride up, pushing the wheel away from the intended path. The guard rail provides a hard boundary that the wheel can be guided against, helping the wheel stay in line with the track and return to the running surface instead of leaving the rails. This is what prevents derailment and maintains straight, safe guidance of the train.

Other options don’t fit this purpose: signals aren’t guided by guard rails, guard rails aren’t primarily for clearance for maintenance equipment, and they aren’t used to reduce track noise.