The first town bus entered service in about 1969 but this was all part of a very informal service. There are other inter-city buses departing the Abu Dhabi central bus station; these inter-city buses are not only intra-emirate buses, but also inter-emirate services. On 30 June 2008, the Department of Transport began public bus service in Abu Dhabi with four routes. There are also public buses serving the airport. In an attempt to entice people to use the bus system, all routes were zero-fare until the end of 2008. The four routes, which operate between 6 am and midnight every day, run at a frequency of 10 to 20 minutes.