 In some cases there are "diferenciales" (special services) which are faster, and notably more expensive.Bus lines in a given city might be run by different private companies and/or by the municipal state, and they might be painted in different colours for easier identification.The city of Buenos Aires has in recent years been expanding its Metrobus BRT system to complement its existing Underground network and it is estimated that, along with other measures, it will increase the city's use of public transport by 30 percent.