The most common traffic problem in cities around the world is traffic jams. Sao Paulo in Brazil has the world’s worst daily traffic jams. According to reports, the historical congestion record was set on June 1, 2012, with 295 kilometres of vehicle queues around the city during the evening rush hour. Some other big cities also suffer from serious congestion in the 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 times. The second reason is that the roads are narrow and sometimes are not good enough. Also, many road users have no respect for traffic rules. As a result, this problem is getting worse and worse. Dịch ra