What are platform screen doors and their purpose?

• A. Doors that block access to the track and are not aligned with train doors.
• B. Doors installed at the platform edge that align with train doors to separate passengers from the track when trains are away.
• C. A barrier at the track perimeter to prevent debris.
• D. An emergency alarm system on the platform.

Answer: (B)

Platform screen doors are safety barriers installed along the edge of a station platform. They line up with the train’s doors and open in sync with them, so passengers can board or alight only when the train is present. When the train has left, the doors stay closed, creating a physical barrier between passengers and the track. This setup greatly reduces the risk of someone accidentally or intentionally stepping onto the tracks while the train is away, and it also helps with keeping the platform environment more controlled.