I. Introduction
The past decade has seen the explosion of intelligent and expert systems, especially in the area of transportation management. Traffic surveillance system (TSS) has gained popularity among researchers and authorities. A key aspect of TSS is to derive the traffic information (count, average speed, and the density of each vehicle type) for further analysis related to traffic management and planning. In this context, many studies have been conducted in developed countries where the transportation frameworks are constructed primarily for automobiles. These systems [1], [2] were developed with the advanced equipment and sensors to optimize the incoming signal including radar, infrared camera and so on. However, in developing countries, the application of these systems has trouble with high cost and incompatible infrastructures. On the contrary, the vision-based TSSs which are built from computer vision and image processing techniques [3]–[5] have shown more superior capability with lower cost and easier to maintain. Moreover, they are extremely versatile as algorithms are designed to cope with a broad range of operations such as detect, identify, count, track, and classify vehicles.