This doesn't have to do with the failed agreement Santa Cruz that was never consumated, but the original agreement with UP to operate the line. They now have to apply to discontinue service. It is all a matter of crossing your i's and dotting your t's.

[www.stb.dot.gov]

Although Sierra has requested revocation, we need not determine whether it has met the criteria to obtain it, because, as a common carrier currently operating on the Line, Sierra is relying on the wrong statutory standard to exit from the Line. To be relieved of the common carrier obligation to serve shippers on the Line, Sierra must obtain Board approval in the form of discontinuance authority, not revocation authority. Pursuant to 49 U.S.C. § 10903 and 49 C.F.R. pt. 1152, a carrier that intends to discontinue service must file an application seeking prior approval by the Board. In some circumstances, a carrier may seek exemption from the prior approval requirements of § 10903 by instead filing a petition for exemption to discontinue service pursuant to 49 U.S.C. § 10502 and 49 C.F.R. § 1152.60, or a notice of exemption to discontinue service under 49 C.F.R. § 1152.50. If Sierra wishes to be relieved of its common carrier obligation, it must avail itself of these Board procedures specific to discontinuances.