This delay in railway connection was detrimental to "the growth possibilities of both regions", causing difficulties in transporting industrial and agricultural products to other markets.

The Asturian Mining Company, owned by the British, established in Mieres by Richard Kelly, was responsible for the first rail link between León and Asturias.

[5] Luciano Castañón wrote that the enterprise failed due to the bond demanded by the Spanish government and the disappointment of the UK envoys.

They "discovered that the country, which they believed to be as flat as Arrowsmith's map, presented such insignificant obstacles to the project as several leagues of mountain ranges, whose peaks reached 6,000 to 9,000 feet and were covered with snow for several months of the year.

[7] In 1861, the route of the branch line was drawn up by the engineers Eduardo Gutiérrez Calleja and Saturnino Adana, and was put up for auction at the end of the same.

[8] The line was to start from Palencia to Ponferrada in León and reach Gijón via Pola de Gordón, Santibáñez, Moreda and Oviedo, with a length of 194.533 km.

On November 10, 1862, the Marquis of Salamanca proposed raising the slope of the route from 1.5 to 4.5 ‰ and reducing the radius of the curves to 250 m, with the aim of keeping the subsidy of a technically unfeasible work.

Finally, the Pajares ramp was inaugurated on August 15, 1884, with the attendance of King Alfonso XII and his wife María Cristina de Habsburgo-Lorena.

[14] The limited transport capacity of Asturian coal to the interior of the Peninsula pushed the company to undertake the electrification of the Busdongo-Ujo section (Rampa de Pajares), the first to be electrified in 3 kV direct current in Spain, in 1924.

Inaugurated in 1957, the line, 14.9 km long, prevented coal trains heading for the ports of Avilés and Gijón from crossing the city of Oviedo and the ramps at Las Segadas.

[17] Between 1966 and 1968, centralized traffic control was implemented on the line and on its branches to San Juan de Nieva and El Entrego, totaling 219 km of track, with a command post in Oviedo.

[20] Subsequently, the Council of Ministers approved that the medium distance line would continue to operate as a public service obligation, with funding from the General State Administration.

[21][22] According to the report Definition of Medium Distance Railway Services to be governed by Public Service Obligations, dated April 2012, carried out by Ineco on behalf of the Secretary of State for Transport of the Ministry of Public Works, in 2010 a total of 1272 train movements were carried out on the line, at a rate of 25 per week, according to data provided by Renfe Operadora.