Rolling Stock 1. What is "brake jam" or "brake hanging"? Why does it not affect safety? 2. When a train loses its power supply, the lighting and air-conditioning become inoperative. Why does it still safe under the situation? 3. Why the nipping of some thin objects (such as plastic bags, etc) cannot be detected by a train door or platform screen door? Can its sensitivity be enhanced? 4. Can a train move if the train doors or platform screen doors have not been closed? What safety precautions will be put in place if the train doors or platform screen doors become defective? 5. Why is it still safe when there is smoke emitting from equipment under the train car?         *In this FAQs, the illustrations of the explanations require Adobe Flash Player for playback