Some 2,500 passengers from 46 flights arrived at Suvarnabhumi airport on the first day of the resumption of the Test & Go scheme on Tuesday.
Kittipong Kittikachorn, the airport's general manager, said arrivals under the scheme came mostly from nearby countries such as Malaysia and Singapore, as well as Europe.
Their registrations were already approved, Mr Kittipong said.
The Customs Department has set up a special lane for passengers arriving in groups with goods to declare, in addition to a lane for general passengers, he noted.
Hotels that have received bookings under the Test & Go scheme have been asked to send vehicles to the airport at least one hour before the tourists arrive to reduce overcrowding, he added.
The airport's fast-track international passenger checkpoint was moved on Tuesday from Zone 2 to Zone 1, located behind the Row A ticket checking counters to improve service efficiency.
Following a makeover, the Zone 1 fast-track checkpoint lane will provide services for first-class and business-class departure passengers and those eligible for fast-track services.
This group includes crew members, holders of diplomatic passports, passengers requiring special assistance (wheelchairs), elderly travellers and pregnant passengers.
New renovations include the expansion of the security checkpoint area and an increase of X-ray machines from two to five.
The number of passport inspection counters has been increased from three to seven to serve 780 people an hour instead of 232, Mr Kittipong said.
The fast-track checkpoint at Zone 2 will be transformed into a passport inspection area for economy class passengers, with more counters added.
This will cater to rising passenger numbers and tackle overcrowding at the international departure passport checkpoint, Mr Kittipong said.
With the improved facilities, he expressed confidence Suvarnabhumi airport would be better able to handle more passengers as travel curbs ease.
It's all part of a greater effort to reopen the country and resuscitate tourism, he added.
The Test & Go programme for fully vaccinated travellers resumed on Tuesday with travellers required to take two tests, one on the first day of arriving and another on the fifth.
The scheme was suspended last month in response to growing concerns about Omicron.
Under the programme, overseas visitors must spend one night in a certified hotel while they wait for the result of their first RT-PCR test.
Those who test negative can leave and explore the rest of the country.
Saksit Mungkarn, president of the Tourism Council of Trat, said Koh Chang is ready to welcome tourists under all travel programmes, including the seven-day sandbox and the Test & Go scheme, as well as domestic travellers.
Some 45 hotels on Koh Chang offer 4,000 rooms that meet Safety and Health Administration (SHA) Plus standards, he said.
Some rooms will serve as isolation facilities for infected tourists who are asymptomatic or have mild symptoms.
"Koh Chang is now fully prepared. We are just waiting for tourists. Before the pandemic, visitors flocked in large numbers to Koh Chang during the Chinese New Year. But this year, it was very quiet," he said, adding a new publicity campaign aims to attract tourists on Valentine's Day.
There is also a plan to reopen Koh Kood, a blue zone, with an improved public health system.