Overground development is nearly always several times cheaper than attempting underground construction. Photo: Le Toan

Ho Chi Minh City Department of Planning and Architecture is finalising an underground space development plan, focusing on the central area of 930 hectares and Thu Thiem New Urban Area in District 2.

Major projects include an underground traffic system connecting Ben Thanh Terminal with the Saigon Opera House Terminal at Metro Line 1, an underground pedestrian walkway in District 1, and more than a dozen other underground projects alongside metro lines that are under construction.

In addition, underground parking lots were planned to be set up under the four current parks of the city. This system would see downtown Ho Chi Minh City’s underground space filled with metro stations, parking lots, shopping malls, and other facilities.

Due to various complexities in the city, developers will find it exceedingly difficult to realise the current plans. According to Ho Chi Minh City Department of Natural Resources and Environment, the area suffers an average landslide of 4cm per year, and even up to 6-7cm per year in some places.

Currently, soft soil accounts for 60 per cent of the city’s land area, mainly in districts 2, 4, 6, 7, 8, Nha Be, Can Gio, and along the banks of the Saigon River.

The area of Ho Chi Minh City has a low natural ground, about 75 per cent of the area with an elevation of less than 2m, and is located in a region strongly influenced by the East Sea tide. The city is regularly impacted by floods when the tide rises, and the sea level is increasing.

Meanwhile according to Le Hoang Chau, chairman of the Ho Chi Minh City Real Estate Association, the investment cost in an underground project is triple that of a project above ground. “To encourage investors, the local authorities should apply appropriate policies to facilitate their access to land and capital resources,” said Chau.

He gave an example that four underground parking lot projects in Ho Chi Minh City were unable to start construction for years despite the planning work being complete.

“Although they are interested in these projects, some investors have backed away due to a lack of clarity in policies and procedures. Moreover, the quota of bank loans for real estate investors is limited,” Chau said.

A lack of databases for the underground system is another problem facing developers in Ho Chi Minh City (HoREA) and the rest of Vietnam. In some cases, developers have to cease construction due to the presence of previously undocumented cables or water pipes in the underground area where their projects are based.

Yeo Choon Chong, CEO for ASEAN at global urban development consulting firm Surbana Jurong, told VIR that careful study must be done because once built, underground space is difficult to redevelop.

“Planning must hence be done in a sustainable manner, and spaces should be designed for permanency or with a high degree of flexibility for change in use, while the implementation can be done in phases,” Chong said.

Chong added that a master plan of underground space in Vietnam should be carried out to review the mapping out the locations of the good geological bearing stratum. “This will help to identify underground development at a lower construction cost since the ground condition in those areas will be better and require lesser need for ground improvement or stabilisation,” Chong said.

Moreover, he added that a demand and supply analysis would be useful to gauge the potential need for any specific underground space usage by incorporating economic, social, and environmental factors, and identify suitable and acceptable underground space usages for current and future alternative functions.

“From an engineering perspective, there is no limit to how much underground space could be potentially derived from below, provided there are no constraints from existing aboveground structures. The limit often lies in the economic and commercial viability of each underground space development,” Chong said.

Despite facing many challenges, experts commented that it is high time for both foreign and domestic investors to look for the opportunity to invest in the underground property system of Vietnam, especially after the first metro line of Vietnam is put into operation. Chong explained that underground space development may be a viable solution for generating more space and optimising land use. The availability of underground space will help to reduce pressure on future aboveground development plans.

“When selecting potential sites for underground space development, a proper study will need to consider their accessibility, the present and planned ground-level usage of these areas, traffic connections, constraints imposed by current operations, and possible landscape and environmental protection values. Space allocations for future projects, such as traffic tunnels and utility ducts, will need to be identified and reserved for future construction,” said Chong.

Chau from the HoREA said underground space development would be a new investment channel for local real estate developers and investors in general. “Developing underground space is crucial in the context of rapid urbanisation. Underground property is therefore expected to be a hot segment of the real estate market in the next several years, attracting retailers and catering service providers,” Chau said.

According to Ho Chi Minh City People’s Committee, about 1,600 buildings in the city have basements and semi-basements with an estimated total area of 11ha. So far, the first Ben Thanh underground trade centre under Metro Line 1 is built across 45,000 square metres, including a commercial stores area and an underground square.

Source: VIR