According to the plan that will be carried out from now until 2030 and with a vision to 2050, the urban space will spread 756 square kilometers across 20 districts of Ba Dinh, Bac Tu Liem, Cau Giay, Dan Phuong, Dong Anh, Dong Da, Gia Lam, Ha Dong, Hai Ba Trung, Hoai Duc, Hoan Kiem, Hoang Mai, Me Linh, Nam Tu Liem, Tay Ho, Thanh Oai, Thanh Tri, Thanh Xuan and Thuong Tin.
The space will have its deepest part go 30 meters underground to have a traffic system, technical and electricity infrastructure, commercial centers, services, supermarkets, entertainment, warehouses and parking lots.
It will be divided into three layers at different depths to serve different functions.
The "shallow layer" at the maximum depth of five meters will serve the construction of underground technical infrastructures like basement entrances and pedestrian tunnels.
The "medium layer" at 5-15 meters deep is for public works and parking areas. The deepest layer at 15-30 meters underground will be for transport systems, including the metro.
Restricted areas for underground construction are Hanoi's Old Quarter, the area outside the embankments of the Red River and its tributary, the Duong River, as there is a risk of affecting dyke safety and flood drainage capacity.
The restriction is also applied for areas nearby and around places classified as special national relics like the Imperial Citadel of Thang Long, President Ho Chi Minh relic site behind the Presidential Palace, the Temple of Literature, Co Loa Citadel, Hai Ba Trung Temple, the Sword Lake, Ngoc Son Temple and zones designated for national defense and security.
According to Hanoi People's Committee, the general planning of underground construction space is to meet the requirements of "state management on construction and use of works to connect and synchronize underground construction space in the area."
"This is the basis for building a database of urban underground construction space, making detailed planning of underground construction space for urban areas as well as conducting underground construction investment projects in the central urban area to work towards building a civilized and modern capital with sustainable urban development.
This general planning decision takes effect from March 15, it stated.