The best and easiest way to explore the old city is on foot, but to get to other areas there is a cheap public transport network consisting of buses, taxis or dolmuses (shared minibus taxis), tramways, and a metro system that has relieved some of the pressure on Istanbul's endless traffic. The rechargeable Akbil electronic transit pass, available from special kiosks, is a discounted way of using local buses, trams, the metro, and ferries.A useful underground metro line runs from Aksaray to the main city bus station at Esenler, and another runs north from Taksim Square, passing the Levent districts. Buses are slow and crowded; tickets must be purchased at outdoor kiosks, as bus drivers do not sell them. Dolmuses and private yellow taxis are more comfortable than the city buses and very inexpensive, but it is advisable for foreigners to have their hotel call a private taxi for them and check that the meter is working, as overcharging is common. A taxi's night rate can be up to 50 percent more expensive than the day rate. Dolmuses can be hailed anywhere along their set routes. Passenger ferries are a pleasant way to see the city. Driving or hiring a car is not recommended due to traffic congestion and poor driving standards.