Going underground: using cities’ hidden space

+ Integrating underground space as part of transit oriented developments (TOD) promotes connectivity in our crowded cities.

As cities continue to expand, urban sprawl and the practice of building on greenfield sites are losing viability. I believe we should start to consider greater use of underground space instead. 

In recent years, more and more Asian cities have invested heavily in underground venues for infrastructure and commercial purposes. In China it’s common to locate urban connectivity underground, while creating new public spaces and commercial zones which benefit from being protected from adverse weather conditions and traffic-dominated roads. Commercially this makes sense too, as the government would benefit from land sales which offset the infrastructure costs, while developers attract greater numbers of commuters through direct connections to their buildings. 

However, there is currently a lack of publicly available information that would be useful to planners and designers for guiding underground developments. To bridge this gap, Arup’s Shenzhen Architecture and Planning team has carried out research into transit oriented developments (TOD) and underground space development in China. This work examines their impact on neighbourhoods, opportunities for commercial integration, operation and management, and effects on the pedestrian experience. 

The research examined 18 metro stations in three Chinese metropolises: Shanghai, Shenzhen, and Tianjin; focusing on transport interchanges located in the city centres and new town developments. The study’s results revealed that integrated design and development produces the most desirable underground spaces, especially when private and public developments are coordinated. Noteworthy is the Shanghai’s IAPM mall and the Metro Line 10 collaboration. 

Spatial comfort and appeal is vital in attracting and retaining footfall. The best underground spaces possess appealing and consistent interior design, as well as integrating natural light and sunken plazas. Effective wayfinding is also important, generating a sense of security and physical comfort for visitors.

To be popular and thus economically viable, underground spaces need to be relevant and multi-purpose to consumers at all levels, from daytime office workers to families on the weekends. Future development of the neighbourhood should also be considered. Not all neighbourhoods are able to sustain underground retail. A good indicator, however, is its proximity to public transportation. 

Often a transit oriented development will connect into a city’s ‘super transport hub’, the wider and complex system of multiple transportation modes that combine with retail, office, residential and civic uses all through underground corridor connections. Super hubs under construction or awaiting the further development of the surrounding neighbourhoods will reserve space within the underground terminals for future metro and bus connections, retaining relevant amounts of retail space for future tenants. In Shanghai’s Hongqiao Airport, its future-proofed design extends the possibility to incorporate the high-speed Maglev train and more retail into the already well connected airport-metro-train-bus-business centre mega hub.

The research defines best practice concepts for future underground transit oriented developments, both for passengers and consumers, as well as the businesses and transport operators that will inhabit them. 

I think in developing cities around the world, political administrations should consider building or expanding their metro rail network into underground spaces. They are no longer just cold, dark and unpleasant links between destinations. In the 21st  century, underground spaces can be vibrant, commercially viable and sociable places in their own right.

How is underground space solving the space constraints in cities you’ve visited or worked in? Use the comments section below to share any great examples.