Subways would seem to be an even harder case for modularization, but when Madrid Metro carried out one of the world’s largest subway expansions between 1995 and 2003, it leaned on modularity in two ways. First, the seventy-six stations required for the expansion were treated like Lego, with all sharing the same simple, clean, functional design. Costs plunged, and speed of delivery soared. To amplify those effects, Madrid Metro shunned new technologies. Only proven technologies—those with a high degree of “frozen experience”—were used.
