Because the changes in traffic behavior, many intersections do not accommodate some common traffic patterns very well. Many intersections affected by heavy turning movements especially left turn movement, Now need three lanes for left turns, which can cause safety and operational problems. Some of these intersections need to be grade-separated, which can be costly. When there is heavy directional movement in more then one direction, most intersections have difficulties accommodating the traffic. If the heavy movements are both ways along the same road, there are often synchronization problems with other signals on the road. (Chlewicki,2007)