GTFS Lines along road network

​@clowncutie Hi there, great question! I noticed that the Snapper transformer is tagged in your question; have you given the AnchoredSnapper a try, by chance? The AnchoredSnapper performs nearly the same action as the Snapper, except with the AnchoredSnapper, you specify one input dataset that is considered accurate, so its features do not move during snapping. 

Try setting up the AnchoredSnapper, where your road network is the anchor dataset, and the bus stops are the candidate features. Then choose the Segment Snapping option for the Snapping Type parameter, and play with the Snapping Distance until you see your bus stops accurately snapping to your roads. 

Let us know how this test goes!