Capital outlays for expansion of Thailand's six biggest airports could run as high as 200 billion baht, according to a new estimate.
The total cost has been inflated by the enlarged scope of work for existing expansion projects and the inclusion of newly planned upgrades at other airports.
The costs for gateway airport Suvarnabhumi and low-cost hub Don Mueang, whose expansions are currently under way, are now projected at 115 billion and 31.9 billion baht, respectively.
Upgrades for the four other airports in Chiang Mai, Chiang Rai, Phuket and Hat Yai have been on the drawing board for some time and are being moved to the Airports of Thailand Plc's (AoT) implementation list.
A budget of 12.8 billion baht has been earmarked for the expansion of Chiang Mai airport, Thailand's fourth-busiest.
Further upgrades for Phuket and new developments at Chiang Rai and Hat Yai have emerged, with overall cost estimated at more than 32 billion baht.
AoT president Nitinai Sirismatthakarn said the state-controlled airport operator's board has approved the master development plans for Suvarnabhumi, Don Mueang and Chiang Mai.
The AoT management is also finalising master development schemes for Phuket, Chiang Rai and Hat Yai, which will be ready for submission to the AoT board this year, he added.
Details of those developments are expected to be released by the end of this month.
The AoT is advocating the expansion and upgrade of all six airports under its auspices to cope with the fast-growing air traffic demand largely being spurred by tourism growth.
The most prominent part of the enhanced expansion for previously known projects is at Don Mueang for the so-called Phase III works.
The Phase III works, costing 28.7 billion baht, include the construction of a building that will connect the airport's terminal with a new mass-transit line, as well as renovation of the existing Passenger Terminal I.
AoT will soon kick off Don Mueang's Phase III after completing Phase II, which largely covered the renovation of Passenger Terminal II last year at a cost of 3.2 billion baht.
The company is due to commence a long-delayed expansion of Suvarnabhumi in August this year. Part of Suvarnabhumi's expansion involves the construction of a third runway and second passenger terminal.
By 2030, Suvarnabhumi, Don Mueang and Chiang Mai are projected to have a combined capacity of 150 million passengers per year, up from 71.5 million at present.