When must a conductor make a safety stop while backing up to a bumper block?

The correct answer indicates that a conductor must make a safety stop while backing up to a bumper block two car lengths away. This requirement is in place to ensure that the train comes to a safe and controlled stop before making contact with the bumper block.

By stopping two car lengths away, the conductor allows for sufficient distance to monitor the train's approach while being able to assess the surroundings and potential hazards. This also provides time to take corrective actions if necessary, ensuring safe operation and minimizing the risk of accidents.

The training for conductors emphasizes the importance of maintaining safety protocols during maneuvers such as backing up, particularly in proximity to fixed objects like bumper blocks. The standard distance allows for effective management of speed and control, which is essential in preventing damage to both the train and the infrastructure.