Saudi Arabia has granted three foreign consortiums contracts worth $22.5 billion (16.9 billion euros) to build a Riyadh metro, the kingdom announced at a news conference in the capital. The consortiums are led by US, Spanish and Italian firms. The 176-kilometre (110-mile) six-line network is aimed at easing chronic traffic congestion in Riyadh, a city of six million people. A consortium led by US engineering giant Bechtel Corp will construct two lines worth $9.45 billion, the official SPA news agency reported. Spanish BTP-FCC consortium will build three of the metro lines for $7.88 billion, after it beat competition from South Korea\'s Samsung, France\'s Alstom and Freyssinet, and Dutch group Strukton to secure the deal. Another line costing $5.21 billion went to Italy\'s Ansaldo. The lines are planned to stretch across the capital and serve the airport and the future King Abdullah Financial District. Oil-rich Saudi Arabia also plans to invest billions of dollars in rail networks linking major cities across the vast desert kingdom. The kingdom already has a 449-kilometre passenger line between Riyadh and Dammam in Eastern Province, with a parallel freight line linking the capital with the Gulf coast city.