This represents a limitation on its maximum passenger capacity per train, which is compensated by one of the highest frequencies in the entire network.

Broadly speaking, its oldest part was characterized by presenting a straight line layout without major technical complications (beyond some pronounced angles), acquiring a more complex and curvilinear shape towards the northeast.

Subsequently, the extensions caused the line to run under Conde del Peñalver Street and, after some short windings, take the López de Hoyos axis, in the direction of Hortaleza.

Once in this district, it draws its final curve, covering a good part of it, until it reaches Pinar de Chamartín.

Thus, the line has stations in the districts of Moncloa-Aravaca, Chamberí, Centro, Salamanca, Chamartín, Ciudad Lineal and Hortaleza, all of which are located in tariff zone A.