Passage:
During sub-zero winter operations, railway track inspection crews use ultrasonic testing cars to scan rails for internal fissures. While standard visual inspections easily spot surface cracks on warm steel, sub-zero temperatures cause existing internal microscopic stress fractures to propagate rapidly before reaching the outer surface. Consequently, maintenance depots schedule ultrasonic scans three times as frequently during winter months compared to summer, even when total train traffic remains unchanged.
Statement: Visual inspections alone are insufficient for detecting dangerous rail defects during freezing weather.
Answer: Answer
Answer
True, because the passage implies that internal stress fractures in freezing conditions grow beneath the surface where visual inspections cannot detect them.
The passage notes that sub-zero temperatures cause fractures to spread internally before becoming visible on the exterior, and that ultrasonic testing must be tripled during winter. This directly implies that visual checks alone cannot safely identify rail defects in freezing weather.
Step-by-Step Solution
Key Concept
Deducing an unstated limitation of a procedure based on context clues regarding internal defect propagation.
Estimated Time:45s