The 2-second rule – the secret to keeping a safe distance while driving
Keeping a safe distance from the vehicle in front is very important, because if you are too close and the vehicle in front brakes suddenly, the vehicle behind will not react in time, leading to an unfortunate accident.
Therefore, experts have created the 2-second rule for drivers to understand and easily apply to ensure safety when driving.
What is the 2 second rule?
To use the 2-second rule effectively, experienced drivers need to observe the car in front passing a landmark such as a sign or a lamp post... and then count. If you count "one second, two seconds", the accuracy is quite low, so you should count evenly: "one thousand and one, one thousand and two", "one zero zero one, one zero zero two". Pronouncing 4 words at a moderate speed will take about 1 second, counting 2 phrases is 2 seconds.
If the mark is reached in less than 2 seconds, it means that the driver is very close to the vehicle in front, so it is necessary to adjust the speed appropriately to increase the safe distance.
While counting mentally, the driver must be absolutely focused. In addition, the driver should also pay attention to the distance from the car behind. When seeing the car behind following closely, the driver should move forward if there is enough space. In case the car continues to move forward, it is best to give way for them to pass.
2 seconds is enough time for the driver to see the car in front brake suddenly, then brake or turn to avoid, to ensure safety. In any case, the driver should have at least 2 seconds to handle the situation quickly and effectively.
However, this rule only applies in favorable road conditions, with high driver concentration and guaranteed. Otherwise, the driver must use the 4-second rule to increase safety with the vehicle in front.
Does the 2-second rule apply in Vietnam?
According to Circular 13/2009/TT-BGTVT, Article 12, when the road surface is dry, the safety distance corresponding to the speed is specified as follows:
| Speed (km/h) | Minimum safe distance (m) |
| 60 | 35 |
| 80 | 55 |
| 100 | 70 |
| 120 | 100 |
Take the current speed minus 30 to get the distance in meters.
For example, 80 km/h: 80 - 30 = 50, so the minimum distance to keep is 50 meters.
Accordingly, when seeing sign 121, the minimum distance between two vehicles, drivers must comply, without needing to apply the 2-second rule.
With complex traffic conditions like in Vietnam, the 2-second rule is not very feasible. Therefore, drivers should flexibly apply it in different conditions:
For national highways, due to the relatively stable traffic situation, drivers can rest assured to strictly follow this rule.
For urban roads, due to crowded and narrow roads, the 2-second rule is difficult to apply. Typically, when traveling at a speed of 15 km/h, 2 seconds is equivalent to a distance of more than 8m from the vehicle in front, so safety will not be high.
For highways, vehicles must travel at very high speeds, so the distance needs to be increased to 3 - 4 seconds to ensure safety, as well as to comply with regulations.
In case of special situations, we cannot use rules mechanically but must be flexible.