tl;dr: Madrid tripled its metro length between 1995-2007 at roughly one-tenth the per-mile cost of London's Jubilee Line, driven by four factors: consolidated regional control that made politicians directly accountable for delivery, aggressive timelines enabled by streamlined environmental reviews and 24/7 tunneling, standardized station designs and proven technology over architectural flourishes, and in-house engineering expertise with contracts evaluated 70% on quality/experience rather than lowest bid. The result was a system now ranking sixth-longest outside China, with higher per-capita ridership than London or NYC.