She was appointed to connect train wires, which requires stripping away outer insulation.

"To accurately strip the wire insulation, I practiced over 200 times every day, and my fingers became callused," she said. "My colleagues and I worked within a space of less than five square meters, so I had to kneel to work for two to three hours at a time."

Yao discovered during inspections in 2018 that despite having uniform wiring standards, the execution varied among workers - some wire ends had burrs, some wire coils were twisted.

"These issues might seem minor on the surface, but they posed safety hazards for train operations," she said.

Yao spent a month devising a solution. She created five electrical sample boards for simulation. Every wire's connection points, wiring positions and directions were meticulously outlined on each board.

"The board looks very intuitive," she said. "As long as wiring is done according to this standard, the quality will be guaranteed."