Some time in the mid 90s I spoke with someone who had worked on this kind of problem (and others) on the London Underground. There had been a desire to know platform occupancy, and that this could be achieved by using a NN. The story as relayed to me was that the NN was never much more reliable that simply measuring the brightness of the platform — or rather the reflection of lights from the platform surface — which could be fairly easily calibrated

I took it less as a cautionary tale about NN and more about looking for simple solutions