ON APRIL 11 two further extensions to the Madrid metro network were opened to traffic, both serving a new interchange at Pinar de Chamart?n which will also be the southern terminus of a light rail route to Sanchinarro and Las Tablas, due to open this month.The 7?km of metro extensions have cost a total of k310m including rolling stock. Line 4 has been extended from Parque de Santa Mar?a, serving intermediate stations at Hortaleza and Manoteras, while the extension of Line 1 from Plaza de Castilla to Pinar de Chamart?n also serves Chamart?n and Bamb?. This had opened as far as Chamart?n on March 30, where a four-level interchange as deep as 30?m underground now provides connections with lines 9 and 10 as well as Renfe main line and suburban services.To the south of the city, the extension of Line 3 from Legazpi to Villaverde Alto was due to open on April 21. Serving six intermediate stations, it will provide interchange with two Renfe suburban routes.