On the IntelliTrain set there are three locations to attach additional scenery. The new scenery will snap into these locations. A rail switch from the add-on will be at the created juncture. It functions like a regular rail switch, thereby allowing the train to pass back and forth. In order to play the new scenarios you must plug the two depots together, and plug the extra scenery into the second depot using the cables on the bottom of the scenery.