Public Space and Porosity of Tall Buildings

Keith Griffiths
Chairman and Global Design Principal
Aedas, Hong Kong

The population density of most cities lies in a range of 3,000 to 6,000 persons per square kilometre.

Traditional city design incorporates transportation and public space infrastructure through a mixture of pavement, roadway and metro with occasional footbridges and subways.

The average density of cities such as Shanghai, Shenzhen and New York exceeds 10,000 persons per square kilometre. At these densities grade separated roads are required whilst at grade roads become extremely wide to handle traffic demands. The roadways create huge separation between city blocks which make at grade pedestrian circulation difficult necessitating systems of footbridges and subways.

Huge areas of cities now exceed 30,000 persons per square metre and at these densities the infrastructure that is required to service the city is massive. Multi-level roads and subterranean transport systems divide the city into huge fortresses of building blocks lacking any form of pedestrian connectivity. The city has become disaggregated by its own infrastructure.

The architecture and urban design of dense cities needs new solutions to reconnect the city.

High-density cities require commensurately greater public space and pedestrian routes. As the ground level of dense cities is insufficient then public space is required at multiple levels above and below ground. Networks of pedestrian routes can seamlessly reconnect our cities above, below and between transportation systems whilst sky parks and raised decks provide the public spaces lost at ground level.

Such networks of pedestrian routes and space will require the lower levels of buildings to be porous and to contain the activity generating facilities hitherto positioned at ground level or within retail podiums. The bases of high rise towers will merge seamlessly into porous, naturally lit and ventilated multi-level public decks, parks and facilities.

Roadways will be segregated from pedestrians thus facilitating pollution free pedestrian access and recreation throughout the city.

The easier and more direct access provided by this new multi-level city will increase the use of cycle and pedestrian access and make the city more enjoyable and convenient.

Embracing the new high density city with an appropriate urban solution will provide a new way of city life which is less polluting, more compact, smart and energy efficient.