Bus Service — The first town bus entered service in about 1969 but this was all part of a very informal service. On 30 June 2008 the Department of Transport began public bus service in Abu Dhabi with four routes. In an attempt to entice people to use the bus system, all routes were zero-fare until the end of 2008. Nowadays, a one-way bus ride is AED 2 (.41 Euro), with 14 bus routes covering the major areas of Abu Dhabi.
Check the following website for more details: https://dot.abudhabi.ae/en/info/Bus_Transportation