The most efficient and reliable public transport in Cairo is the Metro, which has the added advantage of being very cheap. The route connects Helwan in the south of the city to Heliopolis in the north with various branches to Shubra, Ataba and Abdin. There is also a subway line between Giza and Shubra. Trains run from 5.30am to midnight, the first carriage of each reserved for women only. The streets of Cairo are well supplied with taxis, which may have a fare meter but it is not likely to be used. Fares vary and should be negotiated up front and are usually shared. Taxis from hotels tend to cost double that of hailed taxis. The bus and minibus services operating in the city are considered risky for tourists because of overcrowding and the potential for pickpocketing. Buses also require at least a working knowledge of Arabic to navigate. Walking is a fairly good option for taking in the atmosphere of Cairo, but be warned, streets are not marked and maps not much help, so it is easy to lose direction. Driving in Cairo is not for the faint-hearted as few road rules are adhered to, traffic is heavy at all times and streets are poorly signposted. Car rental agencies in Egypt require that drivers be 25 years old minimum and an International Driving Permit is needed