About the factors of traffic problems, there are three main causes why traffic jams in Bangkok are bad. The first cause is that the government introduced a policy to refund tax for first-time car buyers. Because of this, there are more cars on the road than in the past. The second cause is that people lack social values. These people are vendors who sell things and drivers who park their cars on the road. The last cause is police do not take these problems seriously. They let drivers park their cars in no-parking area, and do nothing with vendors who sell thing beside the road, so pedestrians have no choice but walk on the road. This makes traffic jams get worse. All of these problems are why Bangkok is one of the worst cities for traffic.