The 1st July 1883 after about 20 years of projects and works the "Compagnia Reale delle Ferrovie Sarde" network (the present Ferrovie dello Stato company) was terminated. Nevertheless, many areas in the island were without any kind of links, such as Barbagia, Ogliastra, Nuorese, Gallura and Sulcis, the most difficult to reach: the links to the ports - and from them to the rest of the world - were practically inexistent.
The main railway network had to be completed by a "secondary" or "complementary" one that had to be built up according to economic standards. The line was designed following the level ground and it was used the narrow gauge so to reduce the width of the railway and consequently the costs for expropriations. On the other hand, this technique allowed to penetrate into the mountains in an easier way.
1885 (22nd March) Act no. 3011 was passed "giving the government the faculty of granting secondary railways in concession in the island of Sardinia".
1886 (1st August) Royal Decree no. 4041 "for the concession of the construction and management of secondary railways in the island of Sardinia" was passed. The works were assigned to the "Strade Ferrate Secondarie della Sardegna" (SFSS) under the management of engineers Cottrau and Marsaglia.

The works were carried out with a precision and speed that astonished the whole Italy.

1888 (15th February) The first lines were inaugurated: Cagliari-Isili and Monti-Tempio; (26th December) Bosa-Macomer-Tirso.
1889 (6th February) The railway reached Nuoro. (1st March) The Sassari-Alghero line was inaugurated; on the same day, from Isili, the railway reached Meana Sardo to end eventually at the terminus in Sorgono (3rd December).