Since 1985, privately owned ÖHO ("Özel Halk Otobüsü" - Private Public Bus) buses have been allowed to operate under the authority of İETT. There are 2,157 private owned public buses, including 144 double-deckers. There are 783 bus lines excluding diversions as of May 21, 2018. Many routes have diversions running one roundtrip a day on average, which usually feed less developed suburbs around frequent routes. Some routes also provide short turning services at peak hours for crowded stops. Those diversions are listed under the same headsign reference as main route. Buses running diversion routes do not display route numbers, spelling out the route on the headsign in detail instead.