However, the initiative has proved so successful that since early 2012, Car Free Days have been held every Sunday in all five of Jakarta's municipalities. Vehicles were required to possess paper based permits to enter the 32 km2 zone, with exceptions made for public transport, public taxis, emergency, diplomatic and military vehicles. However, difficulties in enforcement meant that as much as 35 per cent of vehicles entering the zone were unauthorized, with only 2 per cent caught and fined by police. To address these enforcement issues, and coupled with improvements to public transport services, the city developed an enforcement system based on automated number plate recognition cameras positioned at each of the 104 road entrances to the restricted zone. The system automatically identifies vehicle registration numbers that have not paid for an annual, weekly or daily pass and subsequently sends out violation notices. By comparison a single ticket on the Tehran BRT ranges from 1,500-2,500 rial (S$0.10 to 0.20).