This subpart applies to each of the following owner/operators:

(a) Described in §1580.1(a)(1) of this part that is a Class I freight railroad.

(b) Described in §1580.1(a)(1) of this part that transports one or more of the categories and quantities of RSSM in an HTUA.

(c) Described in §1580.1(a)(4) of this part that serves as a host railroad to a freight railroad described in paragraph (a) of (b) of this section or a passenger operation described in §1582.101 of this subchapter.