Bilbao has a comprehensive public transport network that consists of a two-line metro system, a city bus service and a single-line tram system. Those using public transport regularly should consider investing in a Creditrans card which charges commuters at a reduced price. While it is possible to hire a car in Bilbao, it is not necessary as public transport covers much of the city. It is actually fairly difficult to drive in Bilbao due to the city's complex road network on hilly one-way streets and construction projects that contribute to heavy traffic congestion. Taxis in the city are run by a single operator, Taxi Bilbao. Vehicles are metered and reasonably priced for short journeys.