The most common traffic problem in city a round the world is traffic jam. Sau Paulo in Brazil has the world's worst daily traffic jam. According to report, the historical congestion was set on June first, 2012, with 295 km of vehicles queues aroung the city during the evening rush hour. Some other big cities also suffer from serious congestions in rush hour. The main cause of this traffic problem is the increase of the population in big cities. So the number of people using the roads has risen several time. Also, many road users have no respect for traffic rules. As a result this problem is getting worst and worst.
