The changes in traffic behavior, many intersections do not accommodate some common traffic patterns very well. Heavy turning movements are often a problem at intersections. Many intersections now need three lanes for left or right 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)