I had an idea for a fun little project the other day, a working dragging equipment detector. In theory it’d be pretty simple to build just mounting it on a micro switch between the rails. That way if the something is dragging or even derailed you could get an actual notification of it (in theory). You could also include a photo sensor to detect a train passing over and randomly generate defects to add operational interest.
At some point I think I’m going to try to build one, I just need to decide whether to retrofit a details west defect detector or build one from scratch (well and time, parts, etc).