Subterranean works, Explained by experts

Engineers Envision Urban Areas That Will Be Home to Billions More By 2050

Engineering has always been about building for what lies ahead—creating lasting legacies in the form of extraordinary buildings or resilient infrastructure that can stand for centuries. Sustainability director from Canadian engineering firm WSP, looks at some of the ways the profession is designing now to be ready for the future.

Now more than ever we need to adopt a future-ready approach to design that anticipates developing trends in climate, society, technology and resources. And although we can’t see precisely into the future, we can build schemes that will be adaptable to suit our changing needs.

We are asking engineers to think about ways to support the hotter, windier, wetter cities that are predicted for decades hence. And that can involve a mind-boggling range of solutions to meet—for instance, the demands set in UN Sustainable Goal 11 focusing on rapid urbanisation.

The United Nations predicts that more than half of humanity, around 5 billion people, will be living in cities by 2030. By 2050 this number will reach over 6 billion. In 2019 cities housed 3.5 billion people and occupied just 3% of the Earth’s land but accounted for 60% to 80% of energy consumption and 75% of carbon emissions. What can engineers do to create places that are safe, comfortable and healthy to live in long into the future?

Options can include creating space without encouraging urban sprawl by building upward and—more challengingly—downward, and planning everything with a fundamental switch to electrical power in mind to reduce carbon emissions.

Solutions don’t necessarily have to be expensive, but they do require engineers to build in flexibility upfront and to explain that need to their clients. Engineers are by definition problem-solvers, and we are challenging them to be at the heart of solving the big issues of the future. We are giving them the chance to create something compelling and exciting that will be around for hundreds of years. Future-ready really is at the leading edge of intelligent engineering.

Let’s look in detail at just one aspect: How you can create extra space in densely developed cities.

Taking Urban Development Underground

Cities are gaining 77 million new residents each year, equivalent to the population of Turkey or Germany and twice that of California. Over the first three decades of this century, the global increase in land cover is expected to be greater than all urban expansion so far in human history. Urban centres ranging in size from 500,000 to 10 million residents will continue to evolve, putting land in these high-density areas at a premium.

Underground construction is creating sustainable opportunities and approaches to address those realities. And there is a growing recognition that the future should include integrated cities where underground facilities link with infrastructure and make life above ground more enjoyable.

Of course, this is not a new concept. In the early 1960s, Montreal embarked on a visionary project designed to cover exposed railway tracks connected to the Central Station in the heart of downtown. The initial development connected an office tower, an underground shopping mall, a major hotel and the station via a pedestrian tunnel system. This has since developed into a network spanning 33 kilometres that is used by as many as 500,000 people and contains bus terminals, business, housing, restaurants, parking, university pavilions and much more.

Sixty years later, there are a growing number of schemes around the world that include plans below the pavement.

For example, in north-central Paris an abandoned underground parking garage below a 300-unit affordable housing complex has become the La Caverne subterranean farm — 3,500 square metres of underground permaculture that produces 54 tonnes of vegetables and mushrooms annually.

And in March, Singapore’s Urban Redevelopment Authority unveiled its 2019 draft masterplan proposals for an inclusive, sustainable and resilient city that included designating three areas to develop underground. The strategy intends to free up surface land for people-centric uses by relocating utilities, transport, storage and industrial facilities underground.

In Sweden WSP is involved in redeveloping the Slussen Bus Terminal in central Stockholm into an underground transport hub linking commuters with buses, trains and metro lines. With surface space at a premium, the decision was made to excavate more than 250,000 square metres of rock to create caverns to house the new underground terminal. When the work is complete in 2023, surface space will be freed up for redevelopment as part of a dynamic new urban quarter.

And in Mexico, Garden Santa Fe in Mexico City is an above-ground park complete with a running track and terrace that surrounds a seven-level underground shopping centre housing retail stores, entertainment, a food court and three levels of parking. Central to the scheme are three inverted glass cones that project natural light and ventilation into the mall.

That’s down, but what about up? Cities have been building skyscrapers for a long time, but finding land for them as development becomes denser and pricier in cities will be a future challenge.

But with clever engineering, space can be conjured out of thin air. At Principal Tower in London WSP helped to create a new 50-story mixed-use development in the air above railway lines but so discreetly that residents never know that trains are running beneath the buildings.

Buildings have been erected over railways before, but the really tricky part for WSP was that almost half of the Principal Tower’s foundation had to leave space beneath in a protected corridor for potential tracks in and out of Liverpool Street station — known as the eight-track corridor. At the same time the architect did not want the conventional, visible, massive arches or A frames that are the usual options for bridging rail lines, so a primary objective was to develop a design that looked like it was built on solid ground. The solution had to be a hidden gem.

We devised a design that involved forming the sides of the protected rail corridor, effectively creating a tunnel.

Future-ready engineering can conjure space out of thin air.

Principal Tower has been a showcase of what is possible with precision engineering in the empty space over railway lines. And the possibilities of that space have been the subject of research at WSP to tease out the full potential of creating space for infrastructure to address London’s housing crisis.

In the study Out of Thin Air, WPS team analysed London’s rail infrastructure and concluded that development of its most viable “overbuild” sites could potentially provide the city with more than 250,000 new homes — or several years’ housing supply. A follow-up report, Out of Thin Air One Year On, aimed to identify the best sites and in doing that found that more than 280,000 new homes are possible at rail overbuild sites.

The benefits of the approach are many. Clearly no new land or major demolition is required. But more importantly, the developments would offer a sustainable solution to urban development. They would give residents greater mobility, placing them closer to rail or metro stations while promoting the ridership of public transport, cutting car use and helping to reduce emissions and improve air quality.

The methodology WSP used to gauge overbuild potential can equally be employed to identify similar opportunities in any dense, space-constrained city anywhere in the world. Applying an informed estimate of 1,200 homes per hectare on rail land indicates that Melbourne, Australia, could create around 77,000 new homes within 10 kilometres of its centre, while Vancouver, Canada, could build 46,000 hew homes. In Copenhagen, the potential is almost 42,000 homes.

By taking a global perspective, engineers are able to draw on best practices from all over the world as they look to tailor solutions for specific circumstances such as growing populations. Future-ready is at the leading edge of intelligent engineering and will have a positive impact as this century unfolds.

The Energy Challenge

The “electrification of everything” is designed to reduce emissions of greenhouse gases and its effect will be largely felt in cities, which account for about 70% of carbon dioxide emissions. The transition to electricity will be one of the defining features of the cities of the future.

WSP are designing schemes in anticipation of an electric lifestyle. In Bermondsey, London, a Grosvenor Estates proposal for 1,600 residential units and 14,800 square metres of flexible commercial space is designed with the idea that cars, heating and day-to-day life will be powered by electricity. Looking at how vehicle patterns mean that residents will move away from car ownership toward pool vehicles, with car club vehicles to be provided on site and facilities put in place in anticipation that many of these will be electric vehicles.

To cope with rising demand for energy, cities are developing innovative strategies to generate, distribute and consume energy as cleanly and efficiently as possible while addressing issues of reliability and security. One such strategy involves the use of microgrids and distributed energy systems.

These represent the next stage in the push toward electrification—a way to reach into the far corners where the big grids cannot go and to make electric service more reliable, clean and less costly.

Most will be located close to a point of consumption, generally in an area with a defined boundary such as a residential district, a university or corporate campus. Microgrids help reduce the cost and potential energy loss involved in transmitting electricity over long distances, support energy reliability because they can disconnect from the grid and operate in “islanded” mode under emergency conditions, and contribute to sustainability goals by incorporating renewable energy sources.

As an example, in Quebec, Canada, Hydro-Quebec is developing a microgrid in Lac-Megantic as a way of testing new technology with the goal of rolling it out elsewhere. Being planned with WSP's assistance, the project calls for the installation of solar panels on 30 residential and commercial buildings with a total of 300 kW installed capacity, 300 kWh of battery storage and electric vehicle charging stations.

Around the world, engineers have signed up to the UN sustainability goals and are developing ways to meet the ambitions. What is clear, and should be for everyone involved in infrastructure, is that for future goals to be achieved, the hard work starts now.

Taking downtown below ground – amazing underground cities

Think of big cities and we think of tall buildings reaching for the sky. But cities also have an infrastructure below street level, with everything from sewers to abandoned tunnels. There are also more signs of life being lived underground than you may have thought. URBAN HUB looks at evidence – ancient and modern-day – of dwellings, concourses, and even a bustling urban life underground. In the world’s increasingly populated cities, planners are building down as well as up.

Doha meets the challenge

Cities Smart inside and out – In many ways, the smart city concept is simply good urban planning that incorporates both advances in digital technology and new thinking in the age-old city concepts of relationships, community, environmental sustainability, participatory democracy, good governance and transparency.

Vertical Earthscraper – Mexico City, Mexico

The future of living underground may soon turn vertical urban living on its head. Architects have developed several plans for deep earthscrapers. One proposed for Mexico City would have a depth of 100 meter, and its inverted-pyramid shape would allow in outdoor light. Imagine a city of these! And with urban mobility innovations like MULTI, connectivity and accessibility would be no problem.

Derinkuyu – Cappadocia, Turkey

Turkey’s Cappadocia region is dotted with underground cities dating back to the 8th century B.C. The largest, Derinkuyu, meaning “deep well,” is an 18-story labyrinth of ventilation shafts, kitchens, wells, a winery, and living space for 20,000 residents. Likely built by the Hittites, it probably served as a refuge during times of war or invasion.

Path – Toronto, Canada

Modern-day underground cities don’t have quite the drama and history of their predecessors. However, they don’t capture our imagination any less. Plus, they can provide some underutilized extra space.

Nearly 30 km long, The PATH in Toronto claims to be the largest underground connected space in the world. Indoor concourses link transit stations and hundreds of stores, restaurants, and entertainment venues. Cities looking to emulate Toronto’s hip and practical underground mall can benefit from installing mobility solutions like ACCEL to keep people moving.

Napoli Sotterranea - Ancient streets – Naples, Italy

Naples embodies the wall-to-wall bustle of a modern city. It’s hard to imagine there being any extra space to breath let alone move. Well, 40 meters below ground, a whole new – or very old – world opens up. The city under the city leads visitors back to its Greek and Roman origins along ancient cobbled streets, past the remains of an aqueduct, market store fronts, and a Roman theater.

Crysta Nagahori – Osaka, Japan

Osaka is world-famous as a shopping city – in part due its underground shopping arcades. The huge shopping malls below the streets often connect the main transit hubs. Crysta Nagahori, which boasts a glass atrium ceiling, indoor streams, and over 100 shops is actually one of the largest shopping malls in Japan – above or under the ground.

Edinburgh Vaults – Edinburgh, Scotland

In the late 18th century, the South Bridge was constructed to help residents reach the south side of town. Nineteen vaults below were included for storage space and workshops for the businesses on the bridge. However, due to dampness, they were slowly abandoned and later taken over by the city’s poor looking for living space. Due to unlivable conditions, the entrances were sealed in the mid-1800s. 100 years later, excavations revealed artifacts of the past and gave rise to ghost stories. So, enter at your own risk!

Coober Pedy – SA, Australia

Australia has its fair share of extreme elements – in the case of South Australia, the heat and roving wild dingoes! In Coober Pedy, known as the “opal capital of the world,” miners and their families find comfortable accommodations and refuge in the real “down under.” Housing for 1,600, plus shops, restaurants, and amazing churches keep residents cozy and cool.

An underground extension in the works, Hong Kong, China

In Hong Kong, what’s driving buildings underground is not an extreme climate, but an extreme space shortage. The city government is now actively supporting businesses in digging into the surrounding mountains and constructing logistics and data centers, laboratories, reservoirs, and recreational clubs. Utilizing this space could free up to 1,000 hectares.

Lowline – New York, USA

If New York can go high, it can go low too. The city has now approved plans for the world’s first underground park – to be built in an abandoned train tunnel on the Lower East Side. It will include an innovative system to allow in sunlight to maintain a forest. The project will also test out new technologies that ensure high air quality and constant temperature. The one-acre park could become an excellent test case for sustaining large communities underground.

Dixia Cheng City – Beijing, China

Beijing also has a modern subterranean world, though it is largely unused. Built in the 1970s, Dixia Cheng stretches across 30 square miles! It included classrooms, barber shops, a roller rink, and even held sites for growing sunless crops. Originally constructed as a massive bomb shelter, its main function today is as a tourist attraction.

Get down with cities of the future

As the world’s population becomes overwhelmingly urban, cities of the future will increasingly need to find more creative and sustainable ways to make use of less space. While many ideas are still on the drawing board, it seems inevitable that earthscrapers and cities-under-cities will continue to grow in popularity and as feasible alternatives.

Source: David Symons, sustainability director for Canadian engineering firm WSP