Global Top Ten Mega-Engineering Projects: From the Medog Hydropower Station to NEOM, the Era of Super Infrastructure

Global Top Ten Mega-Engineering Projects: From Motuo Hydropower Station to NEOM — The Era of Super Infrastructure

What qualifies a project as the “world’s largest engineering project”? The ranking released in 2026 is based on engineering scale and scope, not a simple comparison of budgets. Under this criterion, the ten largest mega-projects still under way across the globe are concentrated in the energy, transportation, urban, and industrial sectors. Spread across construction sites in six major regions, they are collectively defining the engineering capacity limits of our era.

List Overview: The Ten Mega Projects at a Glance

According to Construction Digital’s ranking, the ten largest engineering projects currently under way are:

• Motuo Hydropower Station (Tibet, China): Planned installed capacity of 60 GW, investment exceeding $137 billion, expected to enter commercial operation in 2033.
• NEOM (Saudi Arabia): Total area of 26,500 square kilometers, planned investment exceeding $500 billion. Construction of The Line, its core linear city, has been suspended.
• Gulf Cooperation Council Railway (six GCC states): Total length of 2,177 kilometers, investment of about $250 billion, planned for completion in 2030.
• Dubai Al Maktoum International Airport Expansion (UAE): Area of 56 square kilometers, investment exceeding $35 billion, aiming to become the world’s largest airport.
• King Abdullah Economic City (Saudi Arabia): Investment of $100 billion, covering 173 square kilometers, located on the Red Sea coast.
• South-to-North Water Diversion Project (China): Investment of about $62 billion, with maximum annual water diversion of 44.8 billion cubic meters.
• Nusantara New Capital (Indonesia): Investment exceeding $32 billion; parts of the government core area are now in use.
• Jubail Industrial City Phase II (Saudi Arabia): Investment of $80 billion, covering 6,200 hectares, focused on energy and petrochemical industries.
• California High-Speed Rail (United States): First-phase investment estimated at $89 billion to $128 billion, with the first section targeting opening in 2033.
• Dubai Land (UAE): Investment of $64.3 billion, covering 278 square kilometers.

Behind these figures lies long-term investment by countries in economic growth, energy security, urbanization, and regional integration.

Energy and Water Infrastructure: Storing Energy for Growth

Motuo Hydropower Station is the single project with the largest installed capacity and the highest technical difficulty on the list. Located at the great bend of the Yarlung Tsangpo River, the river drops about 2,000 meters over a 50-kilometer stretch. By excavating four 20-kilometer-long water diversion tunnels, builders will achieve large-scale power generation within the mountain mass of the great canyon, with projected annual power output of 300 billion kilowatt-hours. The station is being invested in and developed by PowerChina, and its installed capacity is nearly three times that of the Three Gorges Dam. However, since the lower reaches of the Yarlung Tsangpo are known as the Brahmaputra River in India, where around 130 million people depend on the river, the project has also sparked discussions on transboundary water governance and geopolitical issues.The South-to-North Water Diversion Project reflects another logic of resource reallocation. Through thousands of kilometers of channels, tunnels, and pumping stations, water from the Yangtze River basin is sent to the arid north China. The eastern and central routes of the project are already in operation, while the western route is still being advanced, and the full construction period is expected to reach 50 years. State-owned contractors such as China Railway Group are among the main construction forces, and the project has strategic significance for the water security of urban clusters in northern China.

Urban and Industrial Ambitions in the Gulf States

Saudi Arabia is one of the most concentrated regions for global megaprojects today. The NEOM project spans 26,500 square kilometers in the northwest and originally planned multiple subprojects. Among them, The Line, a 170-kilometer linear city, was suspended in September 2025 by Saudi Arabia's Public Investment Fund, with internal audits showing its cost could reach as high as $8.8 trillion and require construction until 2080 to complete. NEOM's overall investment has not stopped, but is shifting toward Oxagon's green hydrogen plant and AI data centers. According to data from early 2025, the Oxagon green hydrogen plant was about 80% complete, while NEOM's cumulative spending had reached about $50 billion by 2026.

King Abdullah Economic City is located on the Red Sea coast, covers 173 square kilometers, and is planned to accommodate 2 million residents. The Industrial Valley and special economic zones within the project are attracting automotive supply chains. In May 2025, Emaar The Economic City awarded an infrastructure contract worth $145.9 million for the first phase of the King Salman Automotive Cluster, showing that this economic city is gradually promoting the diversification of Saudi manufacturing.

Jubail II is the core project of Saudi industrial expansion. A new industrial zone of 6,200 hectares will house petrochemical manufacturing, clean hydrogen, carbon capture, and ammonia production facilities, with energy companies such as Shell having participated at different stages. The industrial city aims to become one of the world's largest petrochemical complexes by 2035.

Indonesia, meanwhile, is advancing its new capital, Nusantara, in the jungles of Kalimantan. The relocation plan is intended to avoid Jakarta's land subsidence, congestion, and pollution. Construction began on the project in 2022, and within the core government area, the presidential palace, ministry buildings, hotels, and civil servant housing have been completed; about 10,000 people currently work and live there. Despite a tightened national budget, the new capital is still designed as a smart green city powered by renewable energy.

Dubai Land is one of the few large-scale developments on the list centered on leisure tourism. It plans six themed worlds within an area of 278 square kilometers, including theme parks, sports venues, hotels, and residences. The project also adopts sustainable technologies such as 3D printing, robotic construction, net-zero emissions, and water recycling. However, its development has been intermittent over the past many years, reflecting the interplay between super-large commercial facilities and market cycles.The Gulf Cooperation Council (GCC) railway will, for the first time, link the six Gulf states into a single rail network. On the line with a total length of 2,177 kilometers, passenger trains are designed to run at up to 200 km/h, and the travel time between Abu Dhabi and Dubai is expected to be cut to less than one hour in the future. Saudi Arabia will also build a railway land bridge from Riyadh to Jeddah to connect with the GCC network. Turkish engineering firm Proyapi has won the design contract for the Kuwait section, and general contractors such as China Railway Construction Corporation are involved in some of the construction. According to the latest statement by the GCC Secretary-General, the railway is expected to be completed by 2030.

The Al Maktoum International Airport expansion project is led by Dubai South. It is planned to cover 56 square kilometers, with 5 runways and 4 terminals. With a final designed passenger throughput of 255 million people per year, it will surpass Dubai International Airport after completion to become the world’s largest aviation hub in terms of operational scale. Emirates and flydubai will both move to the airport in the future. This project not only affects airline operations, but also shapes the long-term layout of Dubai’s infrastructure.

California High-Speed Rail is the largest public infrastructure project in U.S. history. The planned route extends from San Diego to Sacramento, with a total length of about 800 kilometers. Current construction is focused on the first segment from Merced to Bakersfield, about 171 miles; more than 80 miles of guideway have been completed, and the track installation contract was awarded in June 2026. Affected by the withdrawal of about $5 billion in federal grants and rising costs, the Phase I budget has expanded from the original $33 billion to between $89 billion and $128 billion. According to the latest estimates, service on the first segment may begin in 2033.

The Engineering Industry: Opportunities and Challenges

These mega projects are driving the entire industrial chain, including design consulting, general engineering contracting, equipment manufacturing, and special materials. Among the projects on the list, companies such as PowerChina, China Railway Group, and China Railway Construction Corporation are taking on major development or contracting roles in Asia and other regions, while regional developers and design firms such as Emaar The Economic City, Dubai South, and Proyapi are advancing specific subprojects. To meet the requirements of highly difficult construction and low-carbon targets, digital twins, BIM, 3D printing, automated robots, and clean energy technologies are being widely adopted. In turn, mega projects are pushing the traditional construction industry toward digital upgrading.

But these projects also face common challenges. First, cost overruns and schedule delays—California High-Speed Rail and NEOM have both experienced budget increases or construction suspensions. Second, there is uncertainty in financing and the political environment. Third, there are engineering risks caused by geological conditions and ecological constraints. For inter-basin water diversion projects and hydropower plants on cross-border rivers, environmental and social impact assessments are equally important.

The Long-Term Focus of Infrastructure InvestmentLooking at the evolution of the ten major projects, individual megaprojects can be paused or redesigned, but global demand for infrastructure construction has not weakened. Urbanization, the low-carbon transformation of energy systems, the construction of new industrial parks driven by supply chain restructuring, and regional connectivity initiatives across various economies are all continuously creating new projects. After NEOM paused the linear city The Line, green hydrogen and AI data centers still received enormous investment; South Asia and Southeast Asia are also promoting upgrades to ports, railways, and urban infrastructure. This shows that global infrastructure investment is becoming more diversified and more technology-oriented, while driving regional economic growth will remain the core mission of the engineering industry for decades to come.