The Two-Second Following Rule works like this. First, find a stationary object on the side of the road. Second, look ahead and notice when the car in front of you passes that stationary object. Once the car in front of you passes the stationary object then measure the time it takes you to pass that same stationary object. If you pass that object before the two seconds pass then you are following too close to the car in front of you. If the time measured is more than two seconds then your following distance is considered safe. However, remember what we said earlier, a two-second following distance only gives the driver a ½ second worth of protection. This two-second time frame would certainly not be enough if it were raining, icy or you were going down a hill.
Another way to get a better understanding of the two-second following distance is to put it in numbers. If a driver is going 20 mph and his reaction time is 1½ seconds, then the car will travel 44 feet in that amount of time. In that 1½ seconds the driver identifies the need to stop, moves his foot from the gas to the brake, and pushes down on the brake. Then the car's braking distance is 19 feet, according to the braking distance chart. This is the distance the car will take to stop once the brakes have been applied. So, if we add the reaction distance of 44 feet to the braking distance of the car then the total stopping distance becomes 63 feet at 20 miles per hour. A simple way to calculate the reaction distance is to simply multiply the speed by 2.2 or make the speed a multiple of 11 like 33 and then multiply by 2. So, 33 times 2 equals 66 which is what the chart states. Another example would be the following: 50 miles per hour would become 55 times 2 and the total stopping distance would be 110 feet, just as the chart on the next page will show.