[6] In 1978, the remaining line to Eudunda and the Robertstown branch came under the ownership of Australian National as part of the SAR's sale to the Federal Government.

The Kapunda to Eudunda section was closed on 11 March 1994 by AN, with the deterioration of the River Light bridge at Hansborough being cited as a reason for closure.

The line's last documented use was on 21 May 2003 by Australian Railroad Group locomotive CK4, though grain services had ceased years before.

The extension continued through Hansborough, running across the River Light once again and Pine Creek before reaching Hampden, then turning south and going through a steep descent into Eudunda.

[4][12] There were proposals to extend the line to connect to Wentworth, New South Wales,[13] and even to Hay to provide a more direct rail route to Sydney.