The most popular form of public transport in Nairobi is the matatu, usually a Nissan minibus, which operate on set routes collecting as many passengers as possible en route, with people boarding and disembarking wherever and whenever they choose. Loud music goes along with the ride in these cheap but unregulated and usually overcrowded vehicles that have become part of Kenyan culture. No less risky, but not as colourful, are the local bus services which operate on set routes and schedules through the city streets, renowned for overcrowding and speeding. Taxis are widely available and convenient, usually congregated in the street around hotels and areas frequented by tourists. Taxis are not metered and the fare should be agreed upon before departure. Nairobi taxis are marked with a yellow line along the side of the vehicle, or they are, surprisingly, large black London taxis. The better taxi companies have more modern vehicles, which can be booked by telephone. Three-wheel auto-rickshaws, or 'tuk-tuks' are also used as taxis in Nairobi.