In 2015, severe floods washed away a series of bridges in Mozambique’s Nampula province, leaving several small villages completely isolated. Breslau, a local engineer and one of our counterparts, knew that rebuilding those bridges would take months. Breslau took his motorbike and drove the length of the river to look for other roads, trails, or paths to help the villagers avoid months of isolation. He eventually found an old earth path that was quickly cleaned up and restored… After a few days, the villagers had an alternative to the destroyed bridge, reconnecting them to the rest of the network and the country.
What happened in the Nampula province perfectly illustrates how a single weather event can quickly paralyze transport connections, bringing communities and economies to a screeching halt. There are many more examples of this phenomenon, which affects both developing and developed countries. On March 30th, a section of the I-85 interstate collapsed in Atlanta, causing schools to close and forcing many people to work from home. In Peru, food prices increase in Lima when the carretera central is disrupted by landslides because agricultural products can’t be brought to market.
How can we help countries improve the resilience of their transport networks in a context of scarce resources and rising climate uncertainty?
Also available in: Português
Over the past three years and a half, our team has been working on a transport project with the state of São Paulo in Brazil. The project involves a lot of traveling, including frequent commutes between the World Bank office in Brasilia and the State Department of Transport in São Paulo (DER-SP)—a journey that is estimated to take 2 hours and 40 minutes. This includes the time to drive from the World Bank office to Brasilia Airport, flight time, and commuting from São Paulo’s Congonhas Airport to the State Department of Transport.
Let’s say that, on a typical Wednesday, the team needs to attend a meeting in São Paulo. To ensure we can make it on time, we plan our day carefully, book our flights and define the right time to leave the office in Brasilia. With a plan in place, we leave the office at 10:00 am and head to Brasilia Airport. The first leg of the trip takes 35 minutes and we manage to arrive early for our 11:00 am flight, which, unfortunately, is delayed by 20 minutes. We land in São Paulo, quickly get out of the terminal, and manage to hop on a taxi at 1:20pm… not bad! We are now on the last leg of our journey, a mere 14-kilometer drive between Congonhas Airport and the meeting place, which is supposed to take only 20 minutes. However, there is a short thunderstorm that floods the city and closes off key streets. This single event leads to complete traffic chaos along the way, and our planned 20-minute transfer from the airport turns into a 1-hour-and-15-minute ordeal. These traffic disruptions have a serious impact on our meeting as well, as some Department of Transport staff cannot join and some items of the agenda cannot be discussed.
This incident may seem anecdotal, but it is a good illustration of our extreme dependency on transport systems and the weaknesses associated with it. Because transport is so critical to our social and economic lives, it is extremely important to understand, anticipate, and minimize the different types of risks that may impact transport systems.
Also available in: Français
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.
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.
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.
When a disaster strikes, such as a hurricane or a major earthquake, relief efforts are often hampered by destroyed or damaged ground infrastructure, mostly roads, bridges, and railway networks. In the days following such a disaster, relief efforts hinge on air transport capacity, which only depends on a clear runway or landing sites for helicopters. First responders, who focus on saving lives, are primarily aviation units of the armed forces or law enforcement.
Almost two weeks ago, when Hurricane Sandy hit the east coast of the United States, the importance of sustainable transport--which is the field I work in--really came home to me. I was in New York for a UN Working Group meeting on transport’s contribution to sustainable development—one of the priorities for Secretary General Ban Ki-moon’s second term.