Taipei City Government

The Taipei City Government held a groundbreaking ceremony and community market for the Dunbei Underground Trunk Drain Project today (July 18, 2026) at Dunbei Park in Songshan District. Taipei Mayor Chiang Wan-an presided over the event, joined by city councilors, borough chiefs, local representatives, and residents from surrounding communities to witness an important milestone in Taipei's transformation into a more resilient city.

According to the Taipei Hydraulic Engineering Office (HEO), Taipei is increasingly facing extreme, short-duration rainfall brought about by climate change. As a highly developed city with extensive impervious surfaces and dense networks of underground utilities, Taipei faces significant constraints in expanding conventional drainage channels. To address these challenges, the HEO drew inspiration from Tokyo's renowned Metropolitan Area Outer Underground Discharge Channel and adopted a new approach centered on stormwater storage. With an investment of approximately NT$1.7 billion, the City is constructing an underground tubular stormwater detention facility, the Dunbei Underground Trunk Drain, to strengthen flood protection along Dunhua North Road and in areas surrounding Taipei Arena during extreme weather events.

The HEO noted that, with space at a premium in Taipei, urban flood control presents significant challenges. To overcome the constraints of limited surface space, the city is making use of deep underground space beneath existing roads to construct Taiwan's first underground tubular stormwater detention facility. The facility will provide a total storage capacity of 32,000 metric tons, equivalent to approximately 16 standard swimming pools. The storage tunnel will have an internal diameter of 6.1 meters and extend approximately 1.1 kilometers from Dunbei Park to Nanjing East Road near Taipei Arena. Using shield tunneling technology, construction will take place approximately 20 to 35 meters underground. Much like performing "minimally invasive surgery" beneath the city, the technique enables excavation deep underground while minimizing disruption to surface traffic and nearby commercial activities.

The HEO also pointed out that during his tenure as a legislator representing Zhongshan and northern Songshan, Mayor Chiang Wan-an took to heart residents' longstanding concerns over flooding and water accumulation. After taking office as mayor, Chiang committed substantial funding to advance the Dunbei Underground Trunk Drain Project, turning residents' concerns into concrete infrastructure improvements. The project is expected to alleviate flooding and create a safer, more livable, and resilient urban environment for residents.

The Dunbei Underground Trunk Drain Project is scheduled for completion by the end of 2029. Once completed, it will become Taiwan's first large-scale underground flood control system equipped with automated monitoring and a new landmark for urban disaster resilience in Taipei. During heavy rainfall, the system will temporarily store stormwater that exceeds the capacity of the existing drainage network and release it gradually after the peak rainfall period, increasing the city's capacity to accommodate extreme rainfall. In addition to better protecting lives and property, the project will further strengthen Taipei's urban resilience in the face of the growing challenges posed by climate change.