The sewer system currently used in Paris was built in the second half of the 19th century and is hailed as the originator of modern sewer systems due to its ingenious design.

      The total length of Paris's sewers is 2,484 kilometers, with about 30,000 manhole covers and over 6,000 underground storage tanks. Every day, more than 15,000 cubic meters of urban wastewater are discharged from the city through this massive system.
 

At the initial design, two separate water channels were built within the utility tunnel, one for collecting rainwater and the other for urban wastewater, so that the tunnel had both drainage and flood discharge functions from the very beginning.
 

      Today, these tunnels are not just sewers; Parisians' drinking water systems, daily street cleaning and urban irrigation systems, chilled water systems for regulating building temperatures, and communication pipelines also run through them to thousands of households. The construction of utility tunnels has greatly reduced the number of times roads need to be dug up for construction.

      Features: Total length has reached 2,100 kilometers, and long-term plans for utility tunnel construction in all major cities have been formulated.

      Japan
      Hibiya Underground Utility Tunnel

      In 1926, during the reconstruction of Tokyo after the Great Kanto Earthquake, Japan completed several common utility ducts, including the one at Kudanzaka, with a total length of about 1.8 kilometers.
 

      The Hibiya Underground Utility Tunnel, constructed using the shield tunneling method, was built more than 30 meters below the surface, with a total length of about 1,550 meters and a diameter of about 7.5 meters. The Hibiya utility tunnel is highly modernized and undertakes almost all municipal public service functions in the area.
 

 

      Features: Shield tunneling is used to build a utility tunnel network system in deep underground spaces.

      Underground Utility Tunnel under Zhangyang Road Sidewalk, Pudong, Shanghai

      In 1994, Shanghai built a dual-cell branch utility tunnel under the sidewalk of Zhangyang Road in Pudong New Area, each cell 5.9 meters wide and 2.6 meters high, with each cell 5.6 kilometers long, totaling 11.2 kilometers. It accommodates gas, communication, water supply, and power pipelines.
 

 

      Features: China's first relatively large-scale operating underground utility tunnel.

      Singapore has detailed planning and design for the development and utilization of underground space: within 20 meters below the surface, water supply and gas pipelines are built; from 15 to 40 meters underground, subway stations, underground shopping malls, underground parking lots, and laboratories are built; from 30 to 130 meters underground, facilities involving fewer people, such as cable tunnels, oil depots, and reservoirs, are built.
 

 

      The Marina Underground Utility Tunnel is 3 meters below ground, with a total length of 3.9 kilometers. The project cost 800 million Singapore dollars (approximately 3.586 billion RMB).

      Features: Accommodates water supply pipes, communication cables, power cables, and even a waste collection system.

      The first utility tunnel in the former East German city of Jena was built in 1945, containing steam pipes and cables to make more rational use of underground space. Today, Jena has 11 utility tunnels, usually at a depth of 2 meters underground, with the deepest one located 30 meters below ground.
 

      This underground utility tunnel can accommodate multiple types of pipelines; water, gas, electricity, communication, and heating pipelines can all share the same tunnel. This makes pipeline inspection, maintenance, replacement, or addition/removal more convenient, with obvious sustainable development advantages.

      Inside the tunnel, pipelines can be placed at the bottom or fixed to the walls with brackets. Protected by the tunnel, pipelines are almost unaffected by external factors such as soil pressure and ground traffic loads, and the materials used for pipelines can be lighter.

      Features: No excavation required for pipeline inspection, maintenance, replacement, or addition/removal, with obvious sustainable development advantages.

      China
      Baiyin City Utility Tunnel

      Baiyin City is one of the first pilot cities for utility tunnel construction. As an important part of the core of Gansu Province, it has 2 districts and 3 counties, covering an area of 21,209 square kilometers.
 

      The current municipal pipelines are old and have insufficient capacity, with numerous pipeline owners and the coexistence of multiple management and no management. The new underground utility tunnel will solve this problem.

      Features: Overall layout integrates high-voltage line burial, underground space, and civil air defense; no-pipe ultra-fine dry powder automatic fire extinguishing device; natural gas pipelines included in the tunnel; all pipelines centrally exit the cabin.
      
      China
      Hengqin New Area Utility Tunnel, Zhuhai

      The Hengqin utility tunnel construction project won the China Human Settlements Environment Example Award. The project has a total length of 33.4 kilometers, five times the length of the underground utility tunnel in the Shanghai World Expo Park. The utility tunnel is at least 3 meters wide and 3 meters high, accommodating 7 types of municipal pipelines including power, communication, water supply, reclaimed water, cooling, heating, and vacuum waste collection systems. It is equipped with ventilation, drainage, fire protection, monitoring, and other systems, centrally controlled by a control center for fully intelligent operation.
 

      Due to the construction of the utility tunnel, a total of over 400,000 square meters of land has been saved. Combined with the current comprehensive land price and urban floor area ratio of Hengqin, the direct economic benefit exceeds 8 billion RMB.
 

      Features: Largest one-time investment, longest construction length, widest coverage area, most pipelines included, and highest construction difficulty.

      Japan
      Yokohama MM21 District Utility Tunnel

       Yokohama Minato Mirai 21 is a waterfront city built by redeveloping part of central Yokohama. It is Yokohama's core project, abbreviated as MM21. The power lines, telephone lines, fiber optic networks, water and sewer systems, and heating systems in the district are all pre-installed in underground common utility tunnels.
 

      Features: A super-large underground space complex planning project integrating tourism, business, shopping, conferences, exhibitions, and museums.