I installed it on Lionel Fastrack just as an exercise, but also on track that was not just a 5 inch straight Lionel track like the sensor tracks. The 072 curve Fastrack shown above is a siding/staging track area and the curve is just about as far into the switch to get out as it can be. So there is enough room to stage a short train behind the engine and still run the tender or diesel over the sensor as the train comes out of the siding. It can also have some cost savings if you want four sensor locations which are all within about 6 feet...maybe like in a yard or some combination of sidings and loop.
It might be interesting to stick one of these sensors into a Fastrack switch...hmmm