The smartest cities are those that build resilience into their design and structure. Devex spoke to two engineers to find out how digital technology tools can help.
The global population is projected to reach 10 billion by 2060 and the majority will live in cities, according to the United Nations. Thousands of new cities will need to be built and existing ones expanded to accommodate this growing population, particularly in Africa and Asia, where the greatest population and urbanization booms are set to take place.
At the same time, the number and severity of natural disasters occurring around the world are increasing. The U.N. reported that in 2015, 346 earthquakes, floods, heatwaves and landslides killed 22,773 people, affected 98.6 million others and caused $66.5 billion in economic damage. This means there is an urgent need to ensure that new and expanded cities are resilient.
Devex spoke to COO Tim Tonyan and Senior Principal Engineer Dennis McCann from CTL Group, a U.S. consulting, engineering and materials testing firm, about ways that “smart” technologies can make it easier and cheaper for urban planners to incorporate resilience into their blueprints.
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However, the CTL experts were keen to point out that “new gadgets” are just part of the resilience solution; low-tech approaches such as the development and application of stringent building codes and standards still have a “tremendous impact on resilience” and can mean the difference between life and death when it comes to earthquakes, such as those that struck Nepal’s capital Kathmandu in 2015 and Italy’s Aquila region in 2016.
“It’s not always about new technology but about bringing existing, good understandings of the way infrastructure performs [to a project],” McCann added.
Nonetheless, technology can bring innovation to resilient design in some key ways.
1. Better inventory of infrastructure
Having an accurate picture, or inventory, of the infrastructure in a town or city is crucial to effectively managing those assets and making informed decisions about future development, Tonyan said. Thanks to new digital tools, the process of inventorying is now easier, cheaper and faster. For example, geographic information systems and building information management systems have become “more mainstream” in recent years, he said, allowing for the creation of visual databases that put huge amounts of detail and information at the viewer’s fingertips.
“With digital mapping tools, you can click on the map and discover the last time a particular pipeline was inspected, for example,” he explained. “If you combine that with sensing technologies then you have an even more useful tool since you can get a snapshot of the behavior of the system.”
For example, if the sensors are registering high levels of seismic disturbance, it could be that the pipe has moved. That knowledge allows the manager to prioritize decisions around repair and maintenance, which is especially important for “remote structures” such as pipes that can be difficult to monitor and reach, Tonyan explained.
Better, digital inventorying systems can also be crucial in a natural disaster scenario such as flooding, Tonyan said. For example, city governors can quickly assess the elevation of protective structures relative to the water level, access information about the city’s transportation systems to assess evacuation routes, and map exit routes by inventorying bridges and roads capable of withstanding high levels of traffic.
Furthermore, when it comes to this approach, developing countries have an advantage because they often have a “clean slate,” unlike the U.S., which is laboring to transfer paper records into new digital systems.
“Incorporating inventorying right out of the gate is a huge advantage since the information from day one can be contained within a single resource,” he said.
2. Use of drones to safely assess structural damage
Drones are “far more than a toy” in the construction industry and can be used both for rapid and remote inventory collection, but also as a way of investigating the “integrity” of a structure in danger of collapse without endangering workers’ lives, according to McCann. For example, drones equipped with video cameras and infrared sensors could be used to fly up into concrete cooling towers at power plants, which are in need of continuous assessment. They could also be used in the aftermath of an earthquake, for example, to search for survivors.
“The equipped drone could get right up next to the element and collect visual information about the condition of the concrete, looking for major cracks for example, as well as its thermal characteristics,” he said. “These are now remarkably affordable technologies and offer us a way to rapidly collect information without putting anyone at risk.”
Drones can also take high-resolution pictures from which engineers can create 3D models, McCann explained. This goes back to the importance of inventorying and provides another safe means of collecting high-quality, rapid data on infrastructures.
3. High-tech building materials to increase resilience and durability
CTL Group’s materials development and testing teams work particularly on concrete, which, as the most widely used material in the world, has a crucial role to play in urban development.
However, concrete can be carbon-intensive to manufacture and can crack if not prepared to the correct proportions. To address sustainability issues, new forms of concrete are being developed to use higher quantities of recycled cementitious material, including pieces of old pavement, Tonyan said.
On the durability side, new “chemical admixtures” — additional ingredients added to concrete before or during mixing — are constantly emerging, which can help it withstand regular freezing and thawing cycles, as well as water-reducing agents to ensure that there is enough water to be able to “work” the concrete without compromising its strength, Tonyan explained.
These kinds of technologies are both “realistic” and “relevant” to infrastructure development in developing countries, he said.
4. Use of sensors to increase the resilience of new buildings and protect existing ones
Temperature sensors can be used to great effect in large concrete structures such as dams, Tonyan said, many of which are being built in developing countries. Monitoring the temperature of the concrete is crucial when working on these structures since overheating can lead to microcracks within the structure, he said. Sensors can be used to collect temperature data so that if it becomes too high, engineers can respond accordingly by cooling the water used to mix the cement or running pipes within the structure, he explained.
Developers can also embed sensors inside concrete structures fitted with strain gauges to detect where the structure is receiving most stress and loading, and thus where it might need repair.
Embedded sensors can also be used during the course of digging foundations for a building, for example, to monitor changing soil conditions and check for “tilt and settlement,” which could signal that adjacent properties are being negatively affected by the construction work. Using these sensors is especially “prudent” in developing countries, Tonyan suggested, where there is often a “lack of documentation” about existing buildings.
“The lack of documentation for the as-built environment creates risks and hazards for those building new resilient infrastructure, but with sensors we can have a better sense of what is going on at the soil level,” he said.
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