Road transport is very limited—only 724 kilometers of the 25,554 kilometer road network are paved, and maintenance on most roads is poor. Only 2% of the freight capacity is supported by river and sea transport, and air traffic is negligible. All port facilities are ice-free and host a merchant fleet of 158 vessels. Eighty-two airports and 23 helipads are operational and the largest serve the state-run airline, Air Koryo. Cars are relatively rare, but bicycles are common. There is only one international airport—Pyongyang International Airport—serviced by Russia and China (see List of public airports in North Korea)