Underground Urbanism

Elizabeth Reynolds

• Publisher: Routledge
• Year: 2019
• eBook ISBN: 9781315523316
• Topic: Architecture
• Subtopic: Urban Planning & Landscaping

Have you ever wondered what lies beneath the streets of your city? Do you picture, in isolation, a series of train tunnels and pipes? Or perhaps the foundations of tall buildings that lie scattered, like icebergs, beneath the surface? As our cities grow up, out, and down, it is time we better understood how the different layers of these complex urban environments relate to one another. Underground Urbanism seeks to provide a new perspective on our cities, and consider how this might be used to engage more positively with them. So, tip your cities upside down to have a closer look, and let us rethink them from (below) the ground, up.

1.

Urban Growth — Up, Out & Down

Urbanism is the study of the way of life, and physical needs of urban societies, however, urbanists are failing to see the whole picture. Our cities don’t just comprise the streetscape and skyline, but also the subsurface. To better understand and resolve the challenges faced by growing cities, it is vital that we begin to look beneath the surface of our city streets. As urban populations grow so does the pressure on land, and for some cities, growing up and out is no longer enough to meet their development needs. Resourceful, design led solutions are necessary to better manage urban growth, and must include a fundamental rethink of our relationship with the ground beneath us. Underground urbanism advocates a vertical stitching together of our urban environments. This book brings together geology, urban planning, engineering, architecture and design, to explain what lies beneath our cities, and how it can be used to create great, sustainable places.

Growing Cities

Physical space is a valuable asset in cities. Housing, manufacturing, transport, utilities, waste, commercial and cultural uses all compete for space in our cities. For cities like Hong Kong, outward growth is constrained by natural barriers, forcing urban density to increase in order to accommodate population growth. In other cities, the limitations on urban growth are theoretical and policy based, using green belts to prevent urban sprawl. In London, demand for access to the centre of a global city has seen development leap over the green belt and stretch into the catchment of a far bigger area. Therefore, whether the constraints to urban growth are physical or policy based, competition for land in our cities is fierce and values are high.

Although it is possible to condense a population into a smaller urban footprint through the construction of tall buildings, spatial challenges remain at ground level where access is needed to and from buildings, particularly during peak hours. Taken cumulatively, the clustering of tall buildings in dense urban areas can lead to insufficient space at street level to safely and conveniently move goods and people.

Fig. 1.1
Density and Urban Realm Capacity, London

> 700,000 sqm, Gross Floor Area

> 12,000 sqm, Public Realm

Urban Connectivity

In growing cities, the connectivity of people and goods is key. From complex rail networks, to purpose designed freight facilities and pedestrian linkages, growing cities rely on transport infrastructure both above and below ground.

Underground passenger rail networks enable high speed travel over long distances without conflicting with vehicle movements at ground level. But as cities grow, so too the networks of infrastructure beneath them. In London, the iconic underground network has expanded to incorporate 400km of track and 270 stations, much of which is underground and integrates with additional stations and tracks on the London Overground and Network Rail. Construction of the latest addition to the London Underground is almost completed, with the Crossrail project (to be known as the Elizabeth Line) due to open late 2018. One of Europe’s largest construction projects, Crossrail will add an estimated 10% to central London rail capacity, with 40 stations, 10 of which will be entirely new. Population growth and decreased car ownership mean however, that further transport capacity is urgently needed, and as such Crossrail 2 is already planned.

Fig. 1.2
Connected London

It is not just people but goods that regularly need to make long distance journeys to the centre of a city. Predicting a 45% increase in road freight traffic between 2010 and 2030, the Cargo Sous Terrain is an innovative solution to improve commercial efficiency, reduce traffic congestion and lower CO2 emission in Swiss cities. Cargo Sous Terrain (CST) was conceived by Swiss company Loglay AG in response to their client’s concerns about inefficiencies in the delivery of their goods to market. To achieve maximum efficiency in the delivery of goods by freight and avoid increasing levels of traffic congestion, it was decided that a new, dedicated freight network was needed underground. The CST network would comprise a 66.7 km long tunnel, 6m in width, located 50m below the existing road network, connecting 10 integrated freight hubs at ground level (Cargo Sous Terrain, 2016). At the purpose designed, integrated hubs freight pallets and containers can be collected from or added to the underground transport system, 24 hours per day, 7 days per week. The hubs and freight network would use 100% renewable energy, mostly sourced from solar panels mounted on the roof of the hubs. The tunnels would be divided horizontally, with the upper section used to move goods, and the lower section used as a conduit for cables and pipes. Larger items or pallets in wagons would move through the tunnel on conveyor belt “tracks” powered by electromagnetic induction and above them, smaller packages would move on tracks suspended from the ceiling. As the system is automated and driverless, the wagons would move at a constant speed of 30km/h and the overhead packages at 60km/h. For the CST to be effective, intelligent city-wide logistics are also required. A key role of the system is to collate freight from different destinations, allowing delivery routes to be scheduled and optimised. Furthermore, the smaller, constantly moving wagons reduce the need for large trucks to wait to be filled before making a commercially viable delivery. The first stage of CST for Harkingen to Niederbipp and Zurich is planned to be operational in 2030 and is estimated to cost $USD 3.5bn. Despite the significant financial investment needed, the project has widespread support from industry and the Swiss Government. Recently, US based technology and transport company Hyperloop One also joined the CST consortium, and there has been interest from other cities hoping this innovative model could also resolve congestion on their roads.

Fig. 1.3
Cargo Sous Terrain, Switzerland

Land Values

Sometimes, regardless of how far out a city expands, or how many layers of transport connectivity it creates, sheer demand for access to the centre of a city can increase land values to a point at which underground development becomes viable. For cities with the world’s highest property values such as London, Hong Kong and Singapore, their unique economic context can even mean that the development of underground space is not just viable, but also profitable.

Iceberg Mansions

In recent years London has seen the emergence of a new building typology known as the iceberg mansion. Iceberg mansions feature predominantly in “super prime” parts of London, and are typified by multi-level basements even greater in area than the original houses to which they are attached. In order to accommodate home cinemas; bowling alleys; swimming pools; spa facilities; or garages, private basements (Wainwright, 2012) have been known to extend as deep as 15m below surface level.

The motivations for developing such large basements are partly lifestyle, but also financial. In the United Kingdom, the rights of a Freeholder extend to an unlimited depth below the surface of a property (except for any gold, silver, treasure, oil, petroleum, coal or gas found beneath the surface, which becomes property of the Crown). Should the subsurface below a private property be compulsorily acquired for an infrastructure project, a nominal fee of £50 is paid to the land owner. Yet, in the case of residential properties in prime areas of London, land values can average £4,779 per square foot (Wetherell, 2015). Given that in 2014 the average cost of a residential basement extension was estimated at £500 per square foot, the financial incentive is clear.

The Iceberg Mansion reflects a broader trend in the property market with many households in central London opting to extend down rather than move out of their house as their family grows. Statistics compiled by Glenigan demonstrate that in 2015 there were 887 applications to develop basements on residential properties in London, up a quarter on the previous year (Croft, 2016). Regardless of scale, excavation to create basements can generate significant construction traffic, alter ground conditions, and undermine the structural integrity of adjacent buildings. Although the introduction of planning policies in some boroughs has led to a decrease in basement planning applications and a reduced scale of development proposals, the small cost to obtain planning consent means that the value of a property is able to increase significantly before the diggers even begin their work. Basement planning policies and the design principles within them are discussed further in chapters three and six.

The Primacy of City Centres

In stark contrast to the mega basements of London, in Beijing an increasing number of people are seeking affordable accommodation in basements beneath the city. A study undertaken by Dr Annette Kim of the University of Southern California titled ‘The extreme primacy of location: Beijing’s underground rental housing market’, found that approximately one million people live in underground apartments in Beijing (Kim, 2016). Beijing has a large amount of subsurface space due to laws requiring the construction of basements as places of refuge during conflict, but able to be used for domestic and economic purposes during peacetime. For many years housing was an allowable use of basement space, however in 2010 regulations were passed to prevent the use of underground space for housing and to evict existing residents within 3 years. Although residential occupancy of basements is now unlawful, and many bunkers and basements are in terrible condition, they remain in high demand. The research identifies basements as providing a housing product at a price not offered by other private rented accommodation, nor available through the public sector. The majority of basement units (some of which are two storeys below ground with no natural light, limited utilities, and measuring just 10 sqm) are occupied by rural residents without the correct Hokou (local birth registration) to benefit from the social services provided by city governments. By undertaking a detailed analysis of classified advertisements, the researchers were able to map the location and price of underground units. The research found that demand for underground accommodation was similar to normal housing, with a premium paid for accommodation closest to the city centre. Indeed, spatial proximity to employment was found to be paramount, allowing residents to save money by walking or cycling to work. Ultimately, the ‘overriding demand for being located in the central city rather than the periphery is the impetus behind this underground housing market’ (Kim, 2016 p.155).

Fig. 1.4
Iceberg Mansion, London

Valuing Land

It is not just the financial value of land that influences the development of space beneath cities, but also the value of land in qualitative terms. For example, where the finance, geology and physical space permits, it can be preferable to relocate transport infrastructure below ground, in order to improve quality of life at street level. From Le Corbusier’s vision of the Radiant City in the 1920s to the American Federal Highway Bill in 1956, the desire to create fast flowing elevated roads has scarred many cities, yet this once popular trend is now being reversed by many cities.

In Seoul, the Cheonggyecheon Restoration Project was transformative in not only removing an elevated roadway constructed in the 1970s, but also restoring a natural stream that had been concreted over years earlier. The project took three years and cost $900 million, an undertaking difficult to justify when it opened in 2005, however, the landscaped pedestrian walk has subsequently proved popular with residents and tourists. For Boston, the Big Dig project was a costly and embarrassing project, blighted by accidents and delays, but ultimately successful. From its construction in 1959, an elevated section of the Interstate 93 highway had divided downtown Boston from its waterfront, with significant impacts on the quality of the urban environment. The elevated roadway became steadily more congested, until it was decided in 1982 to redirect the traffic through a 5.6km tunnel. The Central Artery / Tunnel Project was estimated to be completed by 1998 and cost $2.8 billion, but was not in-fact opened until 2006, by which stage the estimated cost of the project was $15 billion (perhaps up to $24 million with interest). Reasons for the costly delays varied, but included the recall of unsafe materials such as guard rails, lighting fixtures and ceiling panels that had been affixed with a glue unable to safely bond the ceiling panels it was used on (and tragically resulted in a fatality to a road user). The tunnel itself was found to have “hundreds” of leaks, which resulted in primal charges against the concrete supplier for the project. Basic excavation for the project was also difficult, using a slurry wall method in soft, saline, and partly made ground, with no tunnel boring technology available at the time the project was commissioned. Despite all of the money and time invested in the project, it has at least managed to create a positive legacy throug...

Table of contents

• Cover
• Halftitle Page
• Title Page
• Copyright Page
• Table of Contents
• 1. Urban Growth — Up, Out & Down
• 2. Understanding the Underground
• 3. Planning in 3D
• 4. Adapting Underground Spaces
• 5. Architectural responses to the underground
• 6. Creating quality underground places
• 7. As Above, So Below
• 8. References
• Dedication
• Thanks
• Index