Construction will be carried out from August and when work is complete, the airport is expected to have a capacity that can accommodate up to 65 million passengers a year, said president Makin Petplai.
Referring to the construction bidding, the first part will cover the concourse building, 28 parking bays and exit doors, costing 40 billion baht in total, he said.
The second part is the construction of the eastern terminal, costing 7 billion baht, and the third part covers a 2.6-billion-baht public utility system.
Another 1.2 billion baht will be earmarked for consultants and work supervision, he said.
The AoT will find ways to raise funds for the expansion, including loans and fundraising, he said.
Speaking about Don Mueang airport development, Mr Makin said the expansion work is expected to be completed by the third quarter of this year.
It should be able to accommodate 18 million additional passengers per year.
Referring to the regional airports, Mr Makin said Phuket airport's new check-in terminal has already opened.
It will be able to handle eight million passengers a year, three million passengers more than it can take now.
Chiang Mai airport will be able to offer a 24-hour service from next month, he said.
Mr Makin said the AoT projects a 10% increase in passengers this year from 86 million last year, due to an increase in the number of passengers in the Asia Pacific region.
The AoT president admitted Thailand’s political conflict has affected the number of passengers in the first quarter.
“The political turbulence caused the number of passengers to rise only 7.35% from the previous estimate of 10% in the first quarter,” Mr Makin said.
The number of passengers passing through Suvarnabhumi and Don Mueang airports grew 0.5% and 25% respectively, missing the targets of 3.5% and 27%.
If the political problems fail to ease, the passenger target may have to be reviewed, he said.
Mr Makin said the number of passengers using the country's regional airports soared in the first quarter.
Chiang Rai airport saw a 15% increase in passengers, compared with a previous estimate of 7%, while numbers at Chiang Mai airport increased 14.5%, up from an estimate of 13%. Meanwhile, the number of passengers at Phuket airport has exceeded its capacity, he said.
Mr Makin said the global aviation industry is estimated to grow 3.8% a year over the next 20 years, with most of that growth in this region.
That's likely to result in a boost in tourism earnings.
The number of passengers will increase from about 5 billion to 15 billion during the period.
The Asia Pacific region will see the biggest growth in the number of passengers from 1.3 billion to 6.9 billion within two decades, or 46% of the global number of passengers.