Transport in Tanzania includes road, rail, air and maritime networks. The road network is 86,472 kilometres (53,731 mi) long, of which 12,786 kilometres (7,945 mi) is classified as trunk road and 21,105 kilometres (13,114 mi) as regional road.[1] The rail network consists of 3,682 kilometres (2,288 mi) of track. Commuter rail service is in Dar es Salaam only. There are 28 airports, with Julius Nyerere International being the largest and the busiest. Ferries connect Mainland Tanzania with the islands of Zanzibar. Several other ferries are active on the countries' rivers and lakes.