49 C.F.R. § 246.3 – Application and responsibility for compliance.

(a) This part applies to all railroads, except:
1. (1) Railroads that do not have a signal system as defined in § 246.7;
2. (2) Railroads that operate only on track inside an installation that is not part of the general railroad system of transportation (i.e., plant railroads, as defined in § 246.7);
3. (3) Tourist, scenic, historic, or excursion operations that are not part of the general railroad system of transportation as defined in § 246.7; or
4. (4) Rapid transit operations in an urban area that are not connected to the general railroad system of transportation.
(b) Although the duties imposed by this part are generally stated in terms of the duty of a railroad, each person, as defined in § 246.7, who performs any function required by this part must perform that function in accordance with this part.