The second section of the line, from Kondinin to Narembeen, had its contract awarded on 7 February 1917, was constructed that year and officially opened on 22 December 1917, again having been built by the Public Works Department.

The final section of the railway from Narembeen to Merredin had its contract awarded on 11 June 1923 and was officially opened on 16 March 1925, having once more been constructed by the Public Works Department.

[5] In 1954, the state government of Western Australia had compiled a list of loss-making railway operations, of which the Merredin to Yilliminning line was one, having had a total expenditure of almost four times its earnings in the financial year to June 1953.

[7] In 2021, it was estimated that it would cost A$164.41 million to upgrade the Narrogin to Kulin section of the railway line to reopen it.

Reopening the Kondinin to Merredin section was estimated to cost A$210.67 million, or A$238.08 to upgrade the line to standard gauge.