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World Tunnelling Congress: Beneath Thought

As the global population continues to grow, engineers are facing unprecedented challenges to find solutions to the demand for living space and facilities capable of withstanding predicted changes in our planet’s climate. NCE reports from the World Tunnelling Congress in Geneva.

Over the next decades the development of underground space in ways never done before will be central to sustainable development. So expert speakers were briefing delegates at last week’s World Tunnelling Congress.

They called on engineers to play a key role by offering imaginative and innovative solutions on how to develop below ground - and to think of new ways in which sub-surface space can be put to use for the first time.

Former Vancouver vice mayor Dave Cadman said that this century would see huge social changes, but that haphazard or unplanned development could spell disaster for future generations.

Engineers and planners must work together to design new “resilient” cities to cope with global warming, increasing flood risk and continuing demands for resources and land posed by mass migration to urban centres. The pace of urban development made this role critical and immediate, Cadman said.

“There will be more construction over the next 40 years than has taken place in the entire history of mankind,” he claimed. “Two-thirds of humanity lives alongside coasts - and 90% will live in cities by the end of the century.”

Cadman is president of the International Council for Local Environmental Initiatives (ICLEI) - an international organisation of local authorities promoting sustainable development.

“Modern cities have a choice. They can either continue to spread and exacerbate transport problems - or grow on a more compact, dense urban dense model,” said Cadman.

“Some are planning for a 2oC temperature rise from global warming - with a 2m to 3m sea-level rise. Others are now talking about a 4oC rise,” he warned, adding that this presented huge challenges to developers and planners. But engineers must be central to the planning process from the start to devise new solutions for the extreme challenges ahead, he urged.

“There will be more construction over the next 40 years than has taken place in the entire history of mankind”

Dave Cadman, former Vancouver vice-mayor

“There must be more contact between engineers, planners and decision makers. We want engineers and planners to unify their position, together - before coming to decision-makers,” he said. Politicians now wanted to be involved more openly and directly in decision-making than was the case in the past - when some professionals provided them with limited or constrained options to merely rubber-stamp. Engineers and planners need to provide a range of options to allow for the increased involvement of political decision- makers - so must work together earlier.

“If we want to avoid disaster in future, we’re going to have to learn to work together,” he said.
The underground was portrayed as something of a battleground for new thinking on infrastructure development.

“No city can afford to replace all its sewers, it’s simply too expensive. We still have to deal with more rainfall from global warming, but there’s no way we’re going to simply widen sewers to deal with more growth,” Cadman said. Instead, innovative solutions to recycle water were needed as an alternative - using the water from a shower or bath to then flush toilets for example.

Development of underground space was critical to prevent unsustainable urban sprawl as cities seek to grow, he argued.

“Typically around 40% of urban space is taken up by roads - yet we only plan for buildings. There are all sorts of development and buildings which don’t need to be above ground,” said Cadman. Space underneath public land such as highways offered huge potential for development, he added.

Citing a system to recycle heat from wastewater pipes developed in Switzerland, Cadman said it was unknown by Canadian engineers planning for the Vancouver Winter Olympics but adopted after the idea was shared.

“We need to share solutions. We’re looking at building different cities, building for resilience to cope with climate and population change. And we want to share with others, so they’re not reinventing the wheel elsewhere.”

“It cannot be business as usual, it has to change, if we are not to deplete the resources of the planet,” warned Cadman. He said the involvement of private capital was, in his view, essential for sustainable development, so too was public participation.

“We need to look at cities on a city-by-city basis to work out what our future cities will look like. But together we must work with the public to make this happen,” said Cadman.

The United Nations’ special representative for disaster reduction (UNISDR) Margareta Wahlstrom said that global warming and climate change exposed more people to greater risk than before from natural disasters.

Engineers have a key role to play in dealing with these risks, influencing and driving how population centres are designed and protected.

“What is happening now is the biggest transfer of risk in history, determining who will take the risk in disasters. Citizens are increasingly being asked to take more of this risk,” said Wahlstrom.

“What is happening now is the biggest transfer of risk in history, determining who will take the risk in disasters”

Margareta Wahlstrom, United Nations

She said market-driven decisions to opt for the cheapest solutions and materials in design and construction could expose populations and huge numbers of people to greater risk from disasters. One leading US building materials manufacturer had described to Wahlstrom how his firm frequently was required to provide lower quality materials despite having the capability to provide much more robust products, simply because clients were not prepared to pay. Wahlstrom said that this philosophy of market-driven “bottom-line” decisions needed to change - as lower quality construction could mean greater death and destruction when natural disaster strikes, costing more in the long-run in some cases.

“Engineers like you need to become persuaders to help this change,” she said.

The congress also heard plans from architect and engineer James Ramsey of RAAD Studios for the world’s first underground park - in New York’s Lower East Side - where intensive land-use above ground means inadequate recreation space.

The future is downward he said, speaking of massive potential in building below ground. “We need to think earthscraper as opposed to skyscraper,” said Ramsey. His scheme envisages using lighting systems that can capture sunlight and transfer it below ground in an old disused tram depot, enabling propagation of plants.

Delegates heard that Switzerland’s development of underground space was helped by a ban on trucks at night, forcing much freight onto rail and below ground, where 24-hour movement was possible without restriction.

Public demand for a peaceful and less-polluted environment had driven infrastructure development, said Cargo Tube AG managing partner Yvette Korber.

“Cargo [freight] below means better life above,” she said.

Shortage of space coupled with population growth was driving new development solutions underground, Hong Kong’s chief geotechnical engineer Samuel Ng told the congress.

Rock caverns below ground provided big opportunities for sustainable development and are being considered for major sewage works.

“Some see underground development as more suited for NIMBY [not-in-my-back-yard] type facilities - like sewage works, refuse transfer stations or explosives depots for example. Other countries have used underground caverns for other uses such as swimming pools or stadia,” said Ng. “The benefits include enhancement of the land supply above ground, providing flexibility for future expansion while helping the environment,” he added.

But echoing other speakers, he delivered a clarion call to civil and structural engineers to lead the way through ideas.

“Synergy is called for - and we need strong support from contractors and consultants to give us solutions,” said Ng.

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