The work for the implementation of this project, called Stage IV, began in 1999 , with the demolition of the solid construction stations, replacing them with bus stops, and only remodeling the Limache station for the new uses that would later be given to it, making them architectural homologation and functionally. The road was buried with the construction of a tunnel of more than 5 kilometers between the Caleta Abarca and El Salto sectors in the Viña del Mar commune , leaving 4 stations under the street line, and allowing a restructuring of the fascia urban environment via Vina Mar. Because of the work on the tunnel, the service was suspended between July and November 2005.