Manhattan Island

The rise of megacities calls for better infrastructure resilience

Image credit: NOAA, Mark Olsen (US Air Force), Eugene Phoen

People are flocking to cities but without changes, infrastructure could buckle under the stress.

If you like it hot, don’t head for the beach. Go to the city. Researchers from Yale University some years ago found the concrete jungle of cities like London creates ‘urban heat islands’. Temperatures are noticeably warmer inside the city than even within its own ribbon of green belt – the buildings trap heat by day and release it slowly at night. Yet such grey infrastructure also stores up trouble for the future when you look at the city’s ability to survive massive floods.

Not only does concrete store heat in undesirable ways, it prevents water from draining away easily. Floods become a major hazard, as New York and nearby cities in New Jersey such as Hoboken found earlier this decade. Superstorm Sandy hit them so hard in 2012 that city planners have started to look again at how to build defences.

The problems that face New York and the other cities along Hudson River are not isolated. The United Nations estimates 60 per cent of the global population will be urban by 2030. Many new inhabitants will live in new extensions to existing cities in the developing world. Delhi’s population is likely to surge from less than 20 million today to more than 35 million by the end of the next decade. Along with Paris, Mexico City and Moscow, Delhi is a comparatively rare example of a massive inland city. Many emerging megacities, such as Jakarta, Mumbai and Shenzhen, are coastal and prone to massive floods caused by storm surges.

At the Quality Infrastructure Investment conference in February this year, Jolanta Kryspin-Watson, the World Bank’s lead disaster risk management specialist, explained: “With very fast-paced urbanisation, we see a concentration of assets. We see cities becoming megacities at a very fast pace. Yet this fast concentration of assets where disasters are common increases exposure to natural hazards. Overlaid with all this is climate change.”

One thing is becoming clear: we cannot afford them to look like the MegaCity One of science-fiction dystopia ‘Judge Dredd’.

“The future isn’t what it used to be,” said Nancy Kete, director of a programme focusing on resilience at engineering company Arup, at the Lloyds Register Foundation conference in London late last year, shortly after the foundation said it would give the Arup programme £10m. “The future never was like the past, but it used to be a pretty good way to start thinking about engineering design. Certainly, economists use the past as a place to start when thinking about what’s going to happen with global economy. What we believe is that right now, past trends and knowledge you can gain from looking at things in the recent past are increasingly unreliable from a projection point of view. Regression analysis of what happened in the past is going to be misleading.”

Kete added: “These trends of population growth, urbanisation and globalisation are not only large. Now they’re dominant and they’re accelerating. Those of us who think in terms of resilience believe that’s what is now different. The globe has always been populating. It’s always been urbanising. And globalisation has been the dominant trend for a few decades. Yet the scale is increasing.”

Controlling the temperature of the city is a small part of what the change in urban engineering will entail. Already, planners are beginning to push for green roofs that smooth out peaks and troughs of daytime and night-time temperatures, and cut the urban warming effect, but green infrastructure can do much more to help protect inhabitants from greater extremes.

Kete explained: “In our field, we’re starting to talk about park lands that will take water in the time of a tsunami or other kind of flood. We talk about these as berms with benefits. Part of thinking in terms of resilience is to not invest in anything if it only does one thing: think about what other kinds of services you’re going to need.”

Governments have started to take action. In September, the Chinese government approved development of 16 ‘urban sponges’ – redesigned drainage systems that would guide storm waters to collection ponds so the water could be reused later.

An example of the type of design city planners are now considering lies in wetlands of Yanweizhou Park in Jinhua, south-west of Shanghai, China. Architectural consultancy Turenscape, led by Jongkian Yu, an advocate of urban sponges, removed a concrete flood wall used to hem in waters at the confluence of three rivers. This wall disrupted wetlands and concentrated flood water. The redesign demolished the wall and built terraced soil embankments that could absorb some water. Visitors can amble over undulating elevated pathways built over the wetlands.

Surrounded by water and vulnerable to heavy rainfall, Singapore has opted for the urban-sponge model as part of its Active, Beautiful and Clean (ABC) programme – creating green spaces across the island city to absorb water.

The Netherlands, a nation that embraced flood resilience centuries ago, has been redesigning sewer systems and creating water squares that hold storm water.

Financing resilience is potentially difficult in a world where privatisation and deregulation have taken hold. Kete’s former employer, the Rockefeller Foundation, set up funding for a programme called 100 Resilient Cities that encourages the creation of chief resilience officers to oversee planning efforts. Japan’s experience of earthquake-driven turmoil may provide a guide to how markets might be encouraged to engineer for resilience.

Kete pointed to the difference good building design makes: “Chile had an earthquake the same time Haiti did. Chile suffered far less damage than Haiti did because they were prepared. They had building codes and most of the buildings were built to the code.”

Kryspin-Watson noted: “As one structural engineer colleague says: earthquakes don’t kill people, buildings do.”

Cledan Mandri-Perrot, head of infrastructure finance and public-private partnership (PPP) at the World Bank, said the bank is looking at including tests for resilience as part of its Investment Project Financing (IPF) policy. The approach would examine costs of rebuilding after a disaster compared to putting greater resilience into the design at the beginning, and how projects integrate with their environment.

Mandri-Perrot added: “We have to stop planning and building infrastructure as if infrastructure is an exclusive thing that has no effect on its surroundings. The notions of network effects and resilience have to come together.”

One option used by the government in Japan is to put resilience into PPP contracts. In several recent contracts, the private-sector builder took on risks from earthquakes up to a limit, with the government taking over costs of remediation in the event of catastrophic tremors. This left the private-sector constructors and operators with risks for which they could buy insurance.

Yumiko Noda, head of infrastructure and PPP at PwC Advisory, said: “A dialogue between the public and private sector is very important. The public sector needs to understand what kinds of risks can be borne by the private sector.”

However, there are risks if contracts do not anticipate consequences of catastrophic failure and its potential knock-on effects. Kete explained how Superstorm Sandy exposed a key flaw in the way New York handles sewage: “A lot of the wastewater treatment plants throughout New York City in Long Island and the suburbs are built very close to sea level. They backed up in ugly ways. They backed up into people’s houses in the surrounding environment. That’s a case where that infrastructure, which is there to provide the service of handling waste, failed when there was an event that was too large for its design.”

As well as contractors and investors, city inhabitants have to agree to plans. That is far from a straightforward process. On the other side of the Hudson River, the small New Jersey city of Hoboken readied plans to make itself less vulnerable to flooding in the wake of Sandy. The $230m project revolves around four responses to flooding: resist, delay, store and discharge. If built, the scheme will include flood-defence barricades to protect against surges, and conversion of open spaces – including a former chemical plant site – into parks that double up as water-storage tanks able to hold hundreds of thousands of gallons of excess water until it can be pumped into the river.

Yet residents living in expensive properties along Hoboken’s picturesque waterfront split on the plans, presented as five proposals with different levels of defence and construction. “People came to it from different places. Some people had been flooded and didn’t want it to happen again. Others were worried about property values,” Zimmer explained at a seminar on urban resilience at nearby Columbia University.

Residents protested at public meetings and began campaigns of opposition. One resident summed up: “It’s hard to believe that anyone would put forth a plan, let alone five, to put walls around Hoboken. Hoboken is known for its water views.”

Rather than back a plan able to protect 98 per cent of the city flooding from the kind of storm that occurs only once a century, the city’s administration decided to support a cheaper one that provides 85 per cent protection, but is also less intrusive. Instead of walls and gates along the waterfront, this proposal moves part of the flood barrier into an alley, hiding it from view. Where walls need to be built, they will be decorated with flower beds, lighting and furniture so they can be used as tables.

The superstorm that hit the US eastern seaboard in 2012 demonstrated effectiveness of another trend: localised power generation. Universities such as Princeton kept running because they have their own cogeneration plants and are now supplementing them with renewables and storage, rolled into a localised microgrid [E&T May 2017]. Although campus operators did not plan to make a shared resource, they moved quickly to support emergency services.

Ted Borer, energy plant manager at Princeton, said: “Because we were able to keep the lights on, the first responders were able to muster here, recharge their radios and get a hot meal. Even proximity to a microgrid works out for people.”

The task that now faces engineering is working out how best to deal with distributed control of city systems so they work together, not just when things are going well, but when they are under intense stress. 

Kete concluded: “The challenge with resilience is it requires some understanding and consideration of complexity, and of the interdependence of systems and services that underpin modern life. It almost begs for transdisciplinary collaboration.” 

Improve safety by learning from what goes right

Engineering for resilience may pick up on concepts developed for safety-critical systems by psychologist Erik Hollnagel of the University of Southern Denmark. In its Foresight review of engineering resilience, the Lloyds Register Foundation pointed to Hollnagel’s work as an example of new approaches to thinking about resilience.

In 2014, Hollnagel came up with the idea of Safety II to turn traditional safety engineering on its head. The problem he identified is that conventional approaches focus on minimising failures, hopefully to zero. Yet he points out that though the idea of zero accidents and zero injuries “are the right things to say to the public, they are not realistic”. However, determining causes of failure are extremely difficult when only a tiny proportion of data available to plan for those events is usable.

Hollnagel takes the approach that the system needs to be designed so it performs better as much as possible – and use information on how things go right to understand how systems can perform better.

“Safety is a situation where as much as possible goes right. We become safer by having more situations where things go right,” he argues.

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