Huh. There's obviously some state-to-state variances. In Illinois, a regional favorite park line built in the '50s went through all sorts of... uh... "heck" after a new donor and operator started restoring the deteriorated assets. Possibly the difference here was that live steam was involved, and definitely in that case you get into the new boiler regs. But I do recall the state amusement park regulator had to approve the track and rolling stock work, too.