In the Second Half of Urban Competition, the Outcome Is Decided Underground

Cities including London, Singapore, Hong Kong, Wuhan, Shanghai, and Guangzhou are restructuring their underground drainage and wastewater treatment systems through deep tunnel systems: London's Thames Tideway Tunnel (25 kilometers, about 4.6 billion pounds) entered service in 2025, and Singapore's Deep Tunnel Sewerage System (DTSS, 88 kilometers of main tunnels, nearly 10 billion Singapore dollars) is designed for a 100-year lifespan.