Singapore will build a new terminal that will double the capacity of Changi Airport in a bid to retain its edge as a regional aviation hub, Prime Minister Lee Hsien Loong said on Sunday. Construction work will begin soon and will be completed in 12 to 15 years, Lee announced in his annual policy speech \"T5 (Terminal 5) sounds like a terminal, but it is actually a whole airport by itself, as big as today\'s Changi Airport,\" said Lee. He did not reveal the cost of the new facility, but said it would include a third runway that would double the capacity of Changi, which handled 51.2 million passengers last year. Changi Airport, named the world\'s best by Britain-based consultancy Skytrax this year, currently has three terminals with a total capacity of 66 million passengers a year. In February it started to demolish its terminal for budget airlines to replace it with a larger facility. The new facility, Terminal 4, will have the capacity to handle 16 million passengers a year when it opens in 2017. In his speech late Sunday, Lee said there was growing competition from other major international airports in Southeast Asia He noted that Malaysia\'s Kuala Lumpur International Airport and Thailand\'s Suvarnabhumi Airport are planning to expand. \"The question is do we want to stay this vibrant hub of Southeast Asia, or do we want to let somebody take over our position, our business and our jobs?\" Lee said. Passenger traffic at Changi totalled 51.2 million last year, the first time in the airport\'s 31-year history that the number of people passing through crossed 50 million. As of January 1, 2013, Changi handled more than 6,500 weekly scheduled flights with 110 airlines connecting Singapore to 240 cities in 60 countries.