On 1 December 1998, the line was extended from to . The stations in this section were marked with a unique wall color in each station, making it easy to spot one's destination from the train. For example,
Pavones is white,
Valdebernardo is yellow,
Vicálvaro is a light shade of turquoise, and
San Cipriano is orange. This approach is being applied in many other new or recently refurbished stations like
Sevilla on
Line 2, though there is no representation of the colours on official system maps. On 11 July 2008, the infill station
Rivas Futura opened, located between
Rivas-Urbanizaciones and
Rivas Vaciamadrid. On 28 March 2011, the line was extended north from
Herrera Oria to
Mirasierra. On 25 March 2015 the line was extended further north to . Originally, this station was to be named Costa Brava, but because musician and guitarist
Paco de Lucía died in 2014, the Transport Authorities decided to change its name to pay tribute. A
Cercanías railway station opened on 5 February 2018, providing a connection between the two rail systems.
Line 9B At Puerta de Arganda, an island platform was built, so passengers who required to use the southern extension ("line 9B") can move directly across the platform to from the primary route ("line 9A"). This southern extension runs through mostly unpopulated areas connecting the two towns of
Rivas-Vaciamadrid and
Arganda del Rey. The line runs with only two or three car trains at comparatively long intervals through scenic landscape of Spanish desert.
Rivas-Urbanizaciones and
Arganda del Rey are underground stations with large island platforms, and
Rivas Futura,
Rivas Vaciamadrid and
La Poveda are surface stations with side platforms. Given the continuous growth of particularly Rivas-Vaciamadrid, there are many plans for the future of Line 9B. Most concretely, the municipal government intends to construct a new station at Calle José Saramago between Rivas-Urbanizaciones and Rivas Futura and to cover a stretch of tracks to remedy the current state of surface segments effectively cutting the city in half. ==Rolling stock==