Rotate 3D book to a suitable angle, where light will cast shadows properly onto the pages. Added a built-in Photoshop fabric texture to the pages, and used a blue book binding color.
Cut tracks into two pieces, then used the warp tool to bend the tracks to a suitable position, then converted to a 3D extrusion 5 pixels thick then merged with book layer.
Add bridge, which doesn't perfectly merge with tracks, but it is a pop-up book after all. Cut it out and converted to a 3D extrusion 5 pixels thick then merged with book layer.
Like the tracks, I split the train into two part then used the warp tool to bend as needed. Converted to a 3D extrusion 5 pixels thick then merged with book layer.
A lantern, locomotive number plaque, and water tower to fill in the empty spots and the pop-ups are complete. Converted all to 3D extrusions 5 pixels thick then merged with book layer.