The Department of Highways (DOH) is responsible for planning, designing, constructing, and maintaining national highways throughout Thailand. It is therefore the urgent obligations of the DOH to provide both safe and efficient land transport to the public simultaneously. Even though there is no specific statistic in Thailand, it is thought that rearend collision is the most common type of road accidents. Many people have experienced the frustration of traveling behind slow-moving vehicles. Under these conditions, many drivers, especially aggressive drivers, are tempted to follow more closely than they should. This practice, commonly referred to as “tailgating,” is risky and can lead to rear-end collisions or other accidents. When drivers tailgate, they significantly reduce their stopping distance or the distance needed to come to a complete and safe stop. Apparently, the more space drivers allow between their vehicles and the vehicles in front of them, the more time they have to see a hazard and react safely.