A rail overpass toy is a type of toy train set accessory that is designed to replicate a real-life railway overpass. It typically consists of a bridge-like structure that spans over one or more tracks, allowing toy trains to pass underneath. Playing with a rail overpass toy can add an extra level of excitement and challenge to a toy train set, as children can use it to create more complex and varied layouts. It can also be a fun way for children to learn about real-life transportation infrastructure and engineering concepts like bridge construction and weight distribution.