The 1995 ICC Termination Act established the Surface Transportation Board .The Act gave the STB sole authority over the economic regulation of
interstate common carrier railroads. The Durango & Silverton does not carry goods or passengers in interstate commerce nor does it interchange with a carrier that does. As such, it is not under STB jurisdiction .Intrastate status also precludes its employees from participation in the Railroad Retirement system. However,The Federal Railroad Administration does assert jurisdiction over insular carriers like D&SNG in matters of railroad safety.
The C&TS may be different. Clearly its operation crosses state lines. But it may claim it does not provide interstate transportation services since only round-trip excursions are offered. Passengers always end up in the same state that they were in when they boarded. I don't know if that is the logic they use. The intrastate character of C&TS operations may also justify not covering employees under Railroad Retirement.. It would be interesting to learn how the C&TS avoids
Railroad Retirement Board contributions on employes..