Beyond the Surface: Why Cities Invest Billions in Subways to Solve Congestion, Climate, and Land Use Crises

The primary reason large cities choose to bury their high-capacity public transport is the overwhelming constraint of surface space and the necessity of grade separation. In a dense urban core, every available meter of ground level is already occupied by buildings, utilities, roads, and historical sites. Attempting to run high-capacity rail at street level would consume impossibly valuable real estate, require widespread demolition, and create constant traffic conflicts, paralyzing the city entirely.