I just measured again, folded, with foam tube padding as needed. It's 16" wide. Darn. Amtrak's specs limit the width to 15". I could get it down to 15" or less by removing the handlebar at the stem insertion into the fork steering tube. It takes a metric hex ("Allen") wrench. But then I'd have to figure out how to pad it and where to fit it in between the two folded sides of the bike frame somewhere near the front. No room in back due to racks and brakes. I need to be more exact with my measuring. Maybe removing the outside (folding) pedal will shave off a little and turning the brake handles will get a little more. All I need is 1/2" from each side to get down to 15". Still working on it.

Using the idea of the Dahon carryon cover, I hooked a nylon webbing strap around the hinge and the other end through the 2 wheels and up to the rear rack. This lets me lift the folded bike in a balanced manner. Then all I have to add is a light-weight cover that drops over the whole thing, with holes where the nylon strap comes up. Or maybe the folded bike would be lifted and placed into the open cover and the cover then closed around the top with a cinch cord. Working on it.