This Paper presents a prediction model of traffic congestion condition on the roads in Bangkok. The results from our prediction model will be useful for systems related to traffic information. We constructed a model which can achieve 92.1% of accuracy on prediction of the congestion condition in next 30 minutes. Then, we found that the accuracy on the results that change from the current state is unsatisfiable. Hence, we constructed a new model that can improve the accuracy on this portion of traffic data. Moreover, we propose a new performance measurement which can distinguish the results in more detail. The final results show that our approach can improve the accuracy over the former model.