New airports are a rarity these days in modern aviation. Most big cities already have established airports that, in many cases, can be expanded or modernized to suit the city's needs. Some cities don't consider a new airport if the existing airport has additional capacity. City governments sometimes axe proposals to build a new airport, such as in Mexico City, where the existing Benito Juarez International Airport is vastly over capacity. 

Phnom Penh, however, is pushing forward with a new airport slated to open in 2025. Techo Takhmao International Airport will feature three 13,123-foot (4,000-meter) runways and will be the world's ninth largest airport by size, covering 6,425 acres (2,600 hectares). Due to the airport's size, it will be situated approximately 19 miles (30 kilometers) from the city center. When opened, the airport will only be accessible by road, but the minister of transport has suggested that either light rail or metro could be built to connect the airport to the city. 

Techo Takhmao International Airport will fully replace the existing Phnom Penh International Airport (PNH), which was initially aimed to be expanded. The old airport will be used exclusively for diplomatic, government, military, and limited commercial purposes.  The new airport is rather expensive, with a projected cost of $1.5 billion, with most of the money expected to come from bonds sold by the Cambodian government and international financing from Chinese organizations.

The first phase of construction will see the airport handle upwards of 13 million passengers per year, with the airport able to handle up to 30 million passengers per year by the second phase of construction. The existing Phnom Penh International Airport (PNH) saw just under 4 million passengers pass through in 2023, and at its peak, it handled just over 6 million in 2019 before the COVID-19 pandemic.  

The new airport will create an economic boom for tourism and other industries across Cambodia. Additional capacity could allow for more international flights, and its construction has added thousands of jobs. Construction was reported to have passed the 50% threshold in early 2023, and it appears to be on track to open by 2025 if all goes to plan. The new airport has the potential to transform both Phnom Penh and Cambodia.