What should be measured when determining stopping distance?

When determining stopping distance, it is essential to consider both the time taken to react and the distance covered during braking. This approach covers the entire process of stopping a vehicle, which includes the driver's reaction time—how long it takes to identify a need to stop and then physically actuate the brakes—and the actual distance the vehicle travels while the brakes are engaged until it comes to a complete stop.

The stopping distance is composed of two components: reaction distance and braking distance. The reaction distance is influenced by factors such as the driver's attentiveness and the conditions of the road, while the braking distance is particularly affected by the vehicle's speed, the braking capability, road conditions, and vehicle weight.

Considering only the distance covered when braking does not take into account how long it may take for the driver to notice a hazard and begin the braking process. Similarly, focusing solely on the speed of the vehicle ignores the critical aspect of the driver's ability to react promptly. The distance to the nearest gas station is irrelevant when calculating the stopping distance, as it pertains to a completely different context unrelated to safe vehicle operation.

By including both reaction time and braking distance, you get a comprehensive view of how far a vehicle will actually travel before coming to a stop in response to a potential