I use to regularly take George and Hamish on the train to visit my Mum, when she was alive, when they where a lot younger than Billy in fact i carried them in a puppy sack, so it would have been before they wre allowed on the floor
, the journey time was about an hour, they mainly settled under the seat, occassionally if they saw another dog, they might start to bark
but soon stopped. Perhaps, you could try Billy on a short train journey, when it is not too busy
Stephanie, George and Hamish xxx