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Disaster Resilience

The “plastic bridge”: a low-cost, high-impact solution to address climate risk

Oliver Whalley's picture
Also available in: Français
Photo: Anthony Doudt/Flickr
Bridges are critical links in the transport network. In their position across waterways, they are exposed to the full effects of flooding and landslides, and are often the first pieces of infrastructure to be damaged in the event of a disaster. They also typically take weeks or months to repair.  Besides causing expensive damage to the infrastructure itself, disruptions in connectivity also have a much broader impact on economic productivity and people’s ability to access essential services. As many places are expected to witness more intense and frequent rainfall as a result of climate change, the risk to bridges will only worsen: more rainfall will lead to bigger river flows and more damage to bridges, especially those designed to handle smaller storms.

At each end of a bridges is a structure which supports the weight of the deck. These are known as abutments, and they are often the first part of the bridge to fail. Blockage of the main channel by debris can cause water to look for the path of least resistance around the sides of the bridges, thus placing the abutments at risk.

Traditional bridge construction requires the installation of piles for the foundations of abutments—a lengthy and expensive process that involves specialist materials, skills and equipment.

But there is another promising solution: Geosynthetic Reinforced Soil (GRS) abutments. These allow for rapid and resilient construction of bridge abutments using locally available materials, without specialized equipment. With GRS, bridges can be constructed in as little as five days (Von Handorf, 2013) and at a cost 30-50% lower than traditional approaches (Tonkin and Taylor, 2016) .

GRS abutments are based on ‘geogrids,’ a high density mesh made out of polyethylene (plastic). Layers of soil and geogrid are combined to create a solid foundation for the bridge deck. Construction can be completed with basic earthmoving and compaction equipment, and a range of local fill materials can be used with guidance from geotechnical specialists.

Climate change is forcing us to reinvent rural transport for the better

Ashok Kumar's picture
Photo: Ravisankar Pandian/Flickr
India is in the midst of implementing PMGSY, a $35-billion national level Rural Road Program designed to provide basic road access to rural communities. The World Bank is supporting PMGSY through a series of lending operations ($1.8 billion in Bank funding) and significant knowledge support. A key element of the Bank’s support has been to integrate a “climate and green growth lens” into these efforts in cost-effective ways.

How is “green growth” benefiting India? One important dimension of that effort has been  the use of environmentally optimized road designs, which has resulted in quality infrastructure using local and marginal materials, providing both economic and environmental benefits. Where available, sand deposits accumulated from frequent floods, industrial by-products, and certain types of plastic, mining, and construction waste have been used to good effect. Designs that use such materials have been about 25% cheaper to build, on average, than those requiring commonly used rock aggregates. The environmental benefits of using the above materials, in terms of addressing the big disposal problem of such materials and reducing the consumption of scarce natural stone aggregates, are as significant as the cost savings.

A second “green growth” dimension has been focusing investments on the “core” network, i.e. the network India needs to develop in order to provide access to all villages. Relative to a total rural road network of about 3.3 million kilometers, the core network that falls under PMGSY stretches over only 1.1 million kilometers. Prioritizing construction and maintenance on those critical road links will bring down costs as well as the associated carbon footprint.

A new partnership to enhance the climate resilience of transport infrastructure

Shomik Mehndiratta's picture
Photo: Norsez Oh/Flickr
Since 2002, more than 260,000 kilometers of road were constructed or rehabilitated by World Bank supported projects. For these investments, and future Bank transport investments to really realize their intended impact supporting the Bank to achieve its twin goals, we believe it is critical that they are resilient to climate and possible climate change.
 
Already transport damages and losses often make up a significant proportion of the economic impacts of disasters, frequently surpassing destruction to housing and agriculture in value terms. For example, a fiscal disaster risk assessment in Sri Lanka highlighted that over 1/3 of all damages and losses over the past 15 years were to the transport network. Damage is sustained not only by road surfaces or structures, but also by bridges, culverts, and other drainage works, while losses occur when breaks in transport links lead to reduced economic activity.
 
Along with additional stress from swelling urban populations worldwide, rising sea levels, changes in temperatures and rain patterns, and increasing severity and frequency of floods and storm events are the key climate change factors that make conditions more volatile. Ultimately it is these scenarios and their potential outcomes that threaten the longevity and functionality of much existing transport infrastructure. Indeed, damage to transport infrastructure and consequent disruption to communities from climactic events is a growing threat.
 
Compounding the challenge of addressing these conditions is the difficulty that exists in precisely forecasting the magnitude, and in some cases the direction, of changing climactic parameters for any particular location. Meanwhile, the risk of wasting scarce resources by ‘over designing’ is as real as the dangers of climate damage to under designed infrastructure.
 
To identify the optimal response of our client governments to this threat and to ensure that all transport infrastructure supported by the Bank is disaster and climate resilient, we have created a joint partnership between the Bank’s transport and disaster risk management (DRM) communities – a partnership of complementary expertise to identify practical cost-effective approaches to an evolving challenge. We have come together to better define where roads and other transport assets should be built, how they should be maintained, and how they can be repaired quickly after a disaster to enable swift recovery.

A year of building sustainable communities in 12 stories

Andy Shuai Liu's picture
What are some of the key issues that will shape global development in 2017?

​From addressing the forced displacement crisis to helping indigenous communities, and from implementing the “New Urban Agenda” to enhancing resilience to disasters and climate change, one thing is clear: we must step up efforts to build and grow economies and communities that are inclusive, resilient, and sustainable for all—especially for the poor and vulnerable.
 
In the timeline below, revisit some of the stories on sustainable development that resonated the most with you last year, and leave a comment to let us know what you wish to see more of in our “Sustainable Communities” blog series in 2017.

Nepal’s post-earthquake recovery is going well

Annette Dixon's picture
Earthquake survivors set up bank accounts to receive the first installment of 50,000 Rupees each.

The rebuilding has long begun in Nuwakot District in the foothills of the Himalayas in Nepal.

Twenty months after the earthquake that took lives and devastated livelihoods, people are receiving their first payments under a housing reconstruction project and are rebuilding their homes to higher standards. This will hopefully make them safer when the next earthquake hits.
 
The villagers I met were pleased to be getting financial and technical support to rebuild their lives but their frustration over the slow start still lingered. This is understandable given the suffering the earthquake caused and the slowdown in recovery efforts that came soon afterwards because of the disruption at Nepal’s border. But signs of enthusiasm dominated as stonemasons, engineer trainees and local officials mobilize in the rebuilding effort.

Safer buildings are the key to a disaster resilient future

Ede Ijjasz-Vasquez's picture
A few months ago, a 7.8 magnitude earthquake in Ecuador claimed hundreds of lives, left almost 28,000 people injured, and caused $1 to 3 billion worth of damage. Most human and economic losses were directly linked to the collapse of buildings: the tremor caused the destruction of an estimated 10,000 structures, many of which were located in unsafe areas or did not meet minimum safety standards.
 
The tragedy in Ecuador serves as a stark reminder that, in many cases, it is not earthquakes or other disasters that kill people, but failing building structures. Therefore, improving building safety will be key in protecting communities against rising disaster and climate risk.
 
With over a billion dwelling units expected to be built between now and 2050, focusing on new construction will be particularly important, and will help mitigate the impact of natural disasters for generations to come.
 
The good news is that we have the knowledge and technology to build safe, resilient structures. But, more often than not, this knowledge is not put into practice due to insufficient or poorly-enforced regulation, as well as a lack of incentives.
 
In this video, Ede Ijjasz and Thomas Moullier explain why building safety will play a critical role in enhancing disaster resilience, and discuss concrete recommendations on how to get there.
 
If you want to learn more about this topic, we invite you to discover our latest Sustainable Communities podcast.
 
Related:

How can small island states become more resilient to natural disasters and climate risk?

Ede Ijjasz-Vasquez's picture
Small Island States are particularly vulnerable to the impact of climate change and natural disasters. In fact, 2/3 of the countries that have been most severely impacted by disasters are small island nations, which have lost between 1 and 9% of GDP annually due to weather extremes and other catastrophes. The severity and recurrence of disasters makes it hard for those countries to recover, and seriously undermines ongoing development efforts.
 
The World Bank and the Global Facility for Disaster Reduction and Recovery (GFDRR) are actively working with small island states to mitigate the impact of natural disasters and climate risk, including through their joint Small Island States Resilience Initiative. World Bank Senior Director Ede Ijjasz-Vasquez and GFDRR's Sofia Bettencourt tell us more.

Building safer cities for a volatile climate

John Roome's picture
Photo credit: Diego Charlón Sánche


Just consider some statistics. It’s estimated some one point four million people move to cities every week. And by 2050, we will add nearly 2.5 billion people to the planet, with 90 percent of the urban growth in that time taking place in developing countries.

Yet living in cities can be risky business. Many large cities are coastal, in deltas or on rivers and at risk from of flooding from powerful storms or rising sea levels. Globally 80 percent of the world’s largest cities are vulnerable to severe earthquakes and 60 percent are at risk from tsunamis and storm surges.

Fragility, conflict, and natural disasters – a ‘one-size fits all’ approach to resilience?

Francis Ghesquiere's picture
A partner from the EU assesses damage to an apartment building in Ukraine. Photo credit: EU

It’s a simple yet essential idea: war and disaster are linked, and these links must be examined to improve the lives of millions of people around the world.

Alarmingly, the total number of disaster events – and the economic losses associated with those events – keep increasing. This trend has been driven by population growth, urbanization, and climate change, leading to increasing economic losses of $150-$200 billion each year, up from $50 billion in the 1980s. But here is another piece of information: more than half of people impacted by natural hazards lived in fragile or conflict-affected states.

Mother nature and South Asian cities

Rana Amirtahmasebi's picture

Earthquake destruction

In South Asia, 302 million people will join the urban population between 2011 and 2030. If I were one of them, (and let’s assume for a moment that South Asia is one big happy country with no political borders and no religious or ethnic divides), where would I want to live to be safe from natural disasters?

Well, I would probably avoid cities in the mountainous regions of Afghanistan, Bhutan, India, Nepal and Pakistan because they face a high risk of earthquakes and landslides. Cities in northern Pakistan are also at risk of heavy inland flooding. How about the coast? Nope. Data tells me that I should avoid coastal areas in Bangladesh, India, Maldives and Sri Lanka because I do not want my house to be blown away in a cyclone or washed away by a storm surge. Maybe I should live in Bangladesh. Yikes! Chittagong, Sylhet and Dhaka are all in very high earthquake hazard zones. And climate change will cause increased precipitation in eastern South Asia and across India, and warming waters in the Bay of Bengal, which, in turn, will increase the frequency and intensity of cyclones in Bangladesh and on the eastern coast of India.  Indeed, for nine cities around the Bay of Bengal, what is now a 100-year storm event may occur as often as every two to five years by the end of the century. So, those areas are out of the question too.

And the situation is only going to get more difficult.


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