External transport links are by air and sea. Railways and highways for internal communications are well developed. The well-built road networks have a total length of about 10,000 miles. The principal roads consist of a highway running around the island and three east-west highways crossing the island in the northern, middle, and southern regions of Taiwan. A north-south expressway runs across the island. Passenger-bus transportation connecting large cities and small towns throughout the island is provided by the Taiwan Highway Bureau and private transportation companies provide both passenger and freight service. In large cities there are public buses as well as private buses and taxis. Railway is operated by the Taiwan Railway Administration. The mainlines include those from Jilong, in the north, to Gaoxiong, in the southwest; from Jilong to Su'ao, in the northeast; from Gaoxiong to Fangliao, in the south; and from Hualian, in the east, to Taidong, in the southeast. The international seaports are Jilong, in the north; Gaoxiong, in the south; and Hualian, in the east. Jilong is the port for Taipei city, while Gaoxiong is an industrial port. Both cities have good facilities for anchoring large ships. Hualian has also been open as an international port since 1963. Civilian airports include Taipei International Airport, in the north; Gaoxiong Airport, in the southh; and Hualian Airport, in the east. Civilian air transports to Tainan, Taizhong, Taidong, and Penghu are permitted to use the military air bases in those areas. For Taipei International Airport service is available to many metropolitan cities around the world.