A trap and drag incident happens on passenger services when someone gets part of their body or their belongings trapped in closing train doors, and is dragged along the platform when the train departs, which can result in fatal consequences. Many passengers are unaware of the risk of trap and drag incidents and so their actions can be a causal factor. This study was conducted to understand the risks at the platform train interface and whether passenger's mental models of door operations are a contributing factor. In-person and online surveys were carried out and investigation reports on trap and drag accidents were analysed. The study found that participants expect the train doors to work similarly to lift (elevator) doors, which reopen if obstructed. It showed that passenger's mental models of train doors are incomplete and inconsistent causing passengers to take risks which lead to trap and drag incidents.