In this paper, an effective and shadow resistant method is provided to automatically estimate the speed and dimensions of vehicles using video received from a surveillance camera. In this method, at first by examining a few initial frames and considering the motion of vehicles, the vanishing points and focal length of the camera are obtained. Then, by identifying the foreground and removing the shadow, the precise boundary of each vehicle is determined and the 3D bounding box is created for each vehicle. After projecting car on a hypothetical road and eliminating the perspective, the metric coefficient (pixel to meter) is calculated according to the actual dimensions of the dominant car. Removing the perspective and using the metric coefficient allows estimating the speed and dimensions of cars in each frame. But to reduce the error, by tracking the cars, histograms are made for the speed and dimensions of each vehicle. Then the maximum of these histograms is reported as the speed and dimensions of each vehicle. Experiments show better results compared with previous works.The maximum error for the test sets in the speed estimationis 1.17 km/h and in the dimension estimation it equals to 2.6%.