In which situation can a pull-by inspection not be performed after a defect is reported?

A pull-by inspection is a critical procedure used to identify and assess defects on rolling stock or track. It involves a visual inspection of the affected equipment by railway personnel as it passes a designated point.

In the case of a dragging equipment defect, it usually indicates that one or more of the train's wheels or axles are not functioning correctly, potentially leading to significant safety hazards if left unaddressed. Since dragging equipment can cause physical damage to the track and may endanger personnel or vehicles nearby, stopping the train to conduct a pull-by inspection is essential. However, such an inspection cannot be performed with a dragging defect because the equipment must be stopped to assess the severity of the situation. Allowing the train to continue could worsen the condition, leading to derailments or accidents.

In contrast, a broken coupling, faulty signal, or wheel slip detection defect can be assessed through a pull-by inspection, enabling personnel to visually analyze the issues without requiring immediate intervention to stop the train.