Practice makes perfect for 'doctor of the rails'

Track maintenance becomes vital to passenger safety as more trains use high-speed network

Deep in the night, a team of eight men walk slowly along a railroad, the lights from their safety helmets looking like fireflies in the inky blackness.

Ji Fengyun and seven other workers walk 6 kilometers along the Beijing-to-Shanghai high-speed railroad from 12:30 to 4:30 am, Monday through Friday. They are tasked with detecting flaws and defects in the rail tracks, using sophisticated ultrasonic equipment.