Plenty of room at BKK for expansion:
http://www.airport-technology.com/projects/bangkok/
SUBSEQUENT PHASES OF CONSTRUCTION
Long-term plans for four runways flanking two main terminals and two satellite buildings with a combined capacity capable of handling up to 100 million passengers and 6.4 million tonnes of cargo a year are on the drawing board.
The second phase of airport expansion involving the construction of a satellite building south of the main terminal is expected to begin 3–5 years after the completion of the first main terminal.
The third phase of the airport project should take place between 2010 and 2015, when the first passenger terminal will be expanded and a second midfield satellite built, increasing capacity to 73 million passengers annually.
Between 2015 and 2020 a second passenger terminal and fourth runway is expected to be built, lifting capacity to 95 million passengers, followed thereafter by an expansion of the second passenger terminal to allow the airport to reach the expected maximum capacity of 100 million passengers a year.
The IATA is in favour of expansion plans being brought forward, as it believes that, based on current traffic growth, the airport will be short of gates by 2007. It also has concerns about the retail concession layout, noting that the airport's terminal is slightly larger than that of Hong Kong International Airport's, but that the area allocated for retail is only half that of Hong Kong.