In the summer of 2015, I created a miniature, fully functional roller-coaster for the WDI Open House. Using typical components that would been found in a real attraction, the coaster is controlled by a PLC, which monitors various sensors and control boosters to prevent trains from colliding with each other. Block zoning logic was implemented to demonstrate that dangerous situations (such as a train valleying) can be detected and a safe state reached. Due to the small size of the components, some difference in sensing technology was used in lieu of actual sensors. A reed switch was mounted on the track, and magnets in the back of the train was used to provide the PLC with the position of the trains.