The ancient Romans built impressive structures like the Colosseum and the Pantheon, as well as aqueducts spread throughout their empire that have lasted until today. Yet, many recent structures built with modern materials, such as steel and Portland cement, have not survived much longer than their design life of a few decades.
Recently, Massachusetts Institute of Technology researchers discovered the secret to the longevity of Roman concrete: its self-healing properties stem from the so-called lime clasts in the concrete mix, the result of hot mixing of calcium oxide. This discovery may be vital to reducing the carbon footprint of concrete, the most used material after water. Constructing built-to-last infrastructure is a powerful strategy in the fight against climate change. According to a report published by the United Nations Office for Project Services (UNOPS), the United Nations Environment Programme (UNEP), and the University of Oxford, the infrastructure sector is responsible for 79% of all greenhouse gas emissions and 88% of all adaptation costs.
The infrastructure sector is responsible for 79% of all greenhouse gas emissions and 88% of all adaptation costs.
In addition, a study by the University of Cambridge found that the production of materials for the building sector accounted for 11% of global energy and process-related emissions. The same study also revealed that half of all emissions are embodied in buildings, meaning they are caused by the manufacturing of materials and the construction process. Building resilient structures with extended service lives ensures sustainable development and mitigates environmental impacts.
The Need for Long Service Life Infrastructure
First, frequent construction and demolition of infrastructure can have a significant environmental impact. According to the Federal Emergency Management Agency (FEMA), construction and demolition activities contribute to air and water pollution, waste generation, and resource depletion. The production of building materials, transportation of materials to the construction site, and the construction process itself all contribute to carbon emissions. By reducing the need for frequent construction and demolition, long-lasting infrastructure can help mitigate these environmental impacts.
By investing in long-lasting infrastructure governments and private entities can save costs over the project lifecycle and allocate resources more efficiently.
Second, by investing in long-lasting infrastructure governments and private entities can save costs over the project lifecycle and allocate resources more efficiently. According to the World Economic Forum (WEF), rethinking infrastructure policies can lead to better quality-of-life outcomes and stimulate long-term economic growth. Long-lasting infrastructure reduces maintenance, repair, and replacement expenses, which is a significant cost burden for infrastructure owners and operators.
Designing Durable and Resilient Structures
Some examples of resilient structure designs that help mitigate climate change impacts are: Climate-responsive design that creates buildings that use strategies such as passive cooling, natural ventilation, and renewable energy integration. This design includes buildings oriented to maximize natural light and ventilation, and green roofs installed to reduce heat absorption.
Adaptive infrastructure that is flexible, modular, and adjusts to changing climate conditions. For example, roads designed with permeable surfaces allow for water absorption during heavy rainfall, and buildings designed with modular components can easily be replaced or upgraded.
Roads designed with permeable surfaces allow for water absorption during heavy rainfall, and buildings designed with modular components can easily be replaced or upgraded.
Robust buildings that are designed and constructed to withstand severe storms, flooding, and wildfires, and include design solutions based on models of future climatic conditions. They include features such as rainscreens; windows that can withstand hurricane winds; interior finish materials that can dry out if they get wet and do not require replacement; reduced dependence on complex building controls and systems; provisions for manual overrides in case of malfunction or temporary power outages; optimal use of on-site renewable energy; and water conservation practices and reliance on annually replenished water resources, such as harvested rainwater, as the primary or backup water supply.
Sustainable materials that are eco-friendly, durable, and withstand climate impacts. Materials such as bamboo, recycled steel, and cross-laminated timber are sustainable options that reduce construction's carbon footprint. In addition, locally sourced materials help reduce transportation emissions.
Some exemplary, existing long-lasting infrastructure projects include:
The Hoover Dam, built in the 1930s and still operating today, provides hydroelectric power to millions of people.
The Golden Gate Bridge, completed in 1937, is still in use today, with millions of vehicles crossing it each year.
The Great Wall of China, built over 2,000 years ago, is still standing today, making it one of the most impressive examples of long-lasting infrastructure in the world.
Extending Infrastructure Service Life
Robust construction techniques, including high-performance reinforced concrete, advanced engineering systems, and smart monitoring technologies, enhance the durability and longevity of infrastructure.
High-performance concrete is a class of dense, impervious, high-strength material that is much more durable and provides better protection to the steel reinforcement from corrosion. High-performance reinforced concrete is a type of concrete that is reinforced with steel bars or mesh to increase its strength and durability. This technique is commonly used in the construction of bridges, buildings, and other structures that require high strength and durability.
Smart monitoring technologies such as wireless sensors and real-time monitoring systems detect structural damage, corrosion, and other issues that affect the durability of infrastructure. These systems provide real-time data on the condition of infrastructure, allowing for timely repairs and maintenance.
Proactive inspection and maintenance reduce carbon footprints and save money in the long run. By detecting potential problems before they become major issues, preventive maintenance reduces the risk of equipment failure and unplanned downtime. This reduces energy costs and carbon footprints by avoiding the need for emergency repairs and reducing the need for frequent maintenance visits.
In addition, preventive maintenance extends the lifespan of equipment and infrastructure, reducing the need for frequent replacements and repairs. This reduces the amount of waste generated by construction and demolition activities, which can have a significant environmental impact.
Predictive maintenance approaches have proven to be highly cost-effective, saving roughly 8% to 12% over regularly scheduled preventive maintenance and up to 40% over reactive run-to-failure maintenance approaches.
According to the U.S. Department of Energy, predictive maintenance approaches have proven to be highly cost-effective, saving roughly 8% to 12% over regularly scheduled preventive maintenance and up to 40% over reactive run-to-failure maintenance approaches.
Retrofitting and upgrading existing infrastructure enhance its resilience and extend its service life because:
Retrofitting is more cost-effective than building new infrastructure from scratch. According to a report by the National Institute of Standards and Technology (NIST), retrofitting reduces the cost of infrastructure by up to 80% compared to building new infrastructure.
Retrofitting improves the resilience of existing infrastructure by making it more resistant to natural disasters and other hazards. For example, retrofitting buildings with seismic upgrades helps prevent damage during earthquakes, while retrofitting bridges with new materials helps prevent corrosion and other forms of damage.
Retrofitting helps reduce the environmental impact of infrastructure by making it more energy-efficient and sustainable. For example, retrofitting buildings with new insulation and a new HVAC system reduces energy consumption, while retrofitting transportation systems with new technologies reduces emissions.
Some successful case studies of retrofitting are:
The Empire State Building in New York City underwent a $550 million retrofitting project that included the installation of new insulation, windows, and HVAC systems. The retrofitting project reduced energy consumption by 38% and saves the building $4.4 million in energy costs annually.
The San Francisco-Oakland Bay Bridge underwent a $6.4 billion retrofitting project that included the installation of new steel components and seismic upgrades. The retrofitting project improved the bridge’s resilience to earthquakes and other hazards.
The Los Angeles Aqueduct: The Los Angeles Aqueduct is undergoing a multi-billion dollar retrofitting project including the Owens Lake master project. It also included the installation of new pipelines to improve earthquake resistance and other infrastructure upgrades. The retrofitting project has proved to greatly improve the aqueduct’s efficiency and reduced water loss.
The Hong Kong-Macau-Zhuhai sea crossing opened in 2018, with a length of 55 km (34 miles), the longest at the time, built at a cost of $20 billion. It includes a 6.7 km (4 miles) undersea tunnel section and was designed to withstand earthquakes and typhoons. The project was challenging in all aspects, including its location in a very aggressive marine environment, which causes corrosion of steel reinforcement used in concrete structures and any other metal elements.
Its design service life is 120 years while the typical design service life of ordinary reinforced concrete buildings is between 50 and 75 years—important infrastructure projects such as dams and bridges are currently designed for 100+ years of service life. The actual service life that can be realized greatly depends on the structure's regular inspection, repair, and maintenance.
To meet the requirements of the climate transition and Sustainable Development Goals, G20 economies will invest $12.4 trillion in infrastructure projects between 2020 and 2030. Building long-lasting infrastructures is key to these investments and will help reduce the rate of global warming.
Owners, policymakers, and businesses need to consider disincentivizing the demolition of existing infrastructures and, instead, promote the renovation and building of new infrastructures that last a 200-year, if not longer, service life.
How about if today’s structures, such as the Hong Kong-Macau-Zhuhai sea-link or the ones still to be built by the G20, lasted as long as the infrastructure Romans built?
*Dhanada K Mishra is a PhD in Civil Engineering from the University of Michigan and is currently working as the Managing Director of a Hong Kong-based AI startup for building technology for the sustainability of built infrastructure (www.raspect.ai). He writes on issues around the environment, sustainability, climate crisis, and built infrastructure.