Dublin has appalling street congestion in the city centre, but the light rail service known as LUAS (the Gaelic word for 'speed') now offers two lines with numerous stations, many of them giving easy access to the main sights and places of interest. The city also has an extensive bus network, with a limited Nitelink service operating from 1.30am. This, however, is most useful for commuters to and from the city centre. There is also a rapid transit train (DART) that links the city centre with the suburbs and seaside communities.Because most public transport stops before midnight, taxis can be hard to find in the city centre after 11pm, particularly over the weekend. Taxis can be hailed in the street, but it is often easier to find them at taxi ranks or to book ahead by telephone. Renting a car can be impractical and expensive, although they can be essential if visitors want to explore off the beaten track on excursions from Dublin.