The Berlin public transport system is efficient, if expensive, and the combination of buses, trams, ferries, the U-Bahn (underground) and S-Bahn (commuter rail) covers every part of the sprawling city and its surrounds. The U-Bahn and S-Bahn are the best ways of getting around. Buses reach the parts of the city that cannot be reached by train, and East Berlin has a network of modernised pre-war trams. One type of ticket is valid on all forms of transport and fares are divided into three colour-coded tariff zones.Driving in Berlin is easier than in most big cities, but in general is still not recommended. Traffic is heavy and parking difficult to find and expensive. Taxis are plentiful, but it is cheaper to hail one in the street than to call ahead at one of the many call stands around the city. Cycling is a great way to get around. There is an extensive network of bike paths around the city, and bikes can be taken onto most forms of public transport, provided a bike ticket is purchased.