The Cal Osha amusement park inspection rules specifically exempt museums. The rules also exempt rides that are "on the ground" (i.e. railroad track instead of a roller coaster which is generally always on trestle work.)
The program is funded by fees levied on those being inspected, so the inspectors have an interest in extending the number of properties being inspected. They can be heavy handed in their efforts to inspect.
They visited Ardenwood 5 years ago... We quoted their own rules concerning an exemption for museums, and included letters from The California State Railroad Museum, the State Archivist, and the Association of Railroad Museums stating we were a museum and they went away...
Randy Hees