What is the minimum operating duration of the automatic warning device before a train may proceed?

What is the minimum operating duration of the automatic warning device before a train may proceed?

• A. 60 seconds
• B. 10 seconds
• C. 30 seconds
• D. 20 seconds

Answer: (D)

When an automatic warning device is active, there must be a warning window long enough for the crew to observe the signals and react. The device is designed to give at least a twenty-second warning before the train may proceed, providing time to see the signal and prepare to stop if needed. This twenty-second duration balances safety with reasonable train movement across protections. Longer durations (like thirty or sixty seconds) would cause unnecessary delays, while shorter ones (such as ten seconds) might not give enough time to react, increasing risk. If the device doesn’t operate for at least this minimum, movement is not permitted until the device is functioning or proper protection is in place.

When an automatic warning device is active, there must be a warning window long enough for the crew to observe the signals and react. The device is designed to give at least a twenty-second warning before the train may proceed, providing time to see the signal and prepare to stop if needed. This twenty-second duration balances safety with reasonable train movement across protections. Longer durations (like thirty or sixty seconds) would cause unnecessary delays, while shorter ones (such as ten seconds) might not give enough time to react, increasing risk. If the device doesn’t operate for at least this minimum, movement is not permitted until the device is functioning or proper protection is in place.