Two of the biggest airports in the world — Istanbul and Beijing — aim to make travel easier and faster for the passengers who use them.

Air travel is growing in popularity across the world, and the global aviation system is undergoing projects big and small to keep up.

“We’re forecasting that traffic will double in the next 17 years,” said Angela Gittens, director general for Airports Council International (A.C.I. World). “Millions more people will be traveling.”

And those people, she said, won’t just be in places where flying is already popular. “An emerging economy now will be an advanced economy later,” Ms. Gittens said.

New and expanded airports are needed to meet that demand. Istanbul, for example, has already begun opening its new airport in phases that will eventually be able to accommodate hundreds of millions of travelers a year. When it is completed, it will be the world’s largest.

Beijing is set to get its own new airport up and running next year, one that will come close to rivaling Istanbul’s in size and ambition. (It was designed by the architect Zaha Hadid before she died in 2016.)

The key to making both airports manageable for passengers, Ms. Gittens said, is taking advantage of technology to facilitate how people and goods pass through them.

“We have to do things more efficiently. We have to have technology work more efficiently for us. We have to figure out how to process passengers, aircraft and cargo more efficiently in the air as well as on the ground,” she said.

The airports’ designers agreed, and said that efficiency has to start with the buildings themselves.

“We're starting to arrive at scales which were previously unimaginable for the size of these airport buildings,” said Andrew Thomas, a partner at the architectural firm Grimshaw, which designed the Istanbul airport along with the Nordic Office of Architecture and Haptic Architects. “It almost doesn't matter what you put in it if the walks are so long that people are exhausted by the time” they get to their gate.