What is the recommended minimum stopping distance for a car travelling at 100 km/h on a dry road?

The recommended minimum stopping distance for a car traveling at 100 km/h on a dry road is 70 metres. This distance takes into account both the perception and reaction times of the driver, as well as the braking distance required for the vehicle to come to a complete stop.

At higher speeds, such as 100 km/h, the time it takes for a driver to recognize a need to stop and then take action plays a significant role in overall stopping distance. The perception-reaction time, which is typically around 1.5 seconds, adds to the distance covered before the brakes are applied. Following this, the vehicle's braking distance increases substantially with speed due to the physics of motion. For example, under ideal conditions, a car can take roughly twice as long to stop at higher speeds when compared to lower speeds.

In this case, the choice of 70 metres provides a safe buffer for a driver operating under normal conditions, ensuring they can stop effectively without risking accidents due to inadequate stopping distance. Choosing a distance that is either significantly less or greater could lead to unsafe driving situations or distortions in driver expectations of stopping capabilities. Thus, understanding and adhering to this stopping distance is crucial for safe driving practices.