I am not a model train enthusiast but have a son that LOVES trains. He is almost 6 now and ever since he was 2 his favorite thing in the world has been trains. Almost all of his toys are trains. Every time he gets a new one his face lights up. He still plays with all of them that he has that are not broken. That is the problem I have. He keeps getting cheep train sets for Christmas and birthdays etc and they last for a while till they get dropped and the battery door breaks off etc. What I want to do is get him a good train and set up a track that goes around the top of the wall in his room that he can start and stop without having to touch it (and that his 2 year old brother who also likes to play with the trains can’t get to). I understand that HO is the most popular scale but I am afraid that will be too small to see. I cannot find anywhere that tells what average size each scale is. What I am looking for is a scale where the engine and cars are approximately 3-4“tall. My next question is about layout. His room is 12.5’ X 9.5’ which gives me a linear distance of 44’ but what I do not know is how much track to get. I know that I may run into issues making the turns. Can anyone provide a link to a page (or other threads here) that outline the amount of space required to make a 90 turn in each of the scales? Thank you in advance. If this anything like the boating boards that I am a member of I know that this group will be a wealth of information.