3 ms·

Anyone discussing braking margin/safety at speed in car-lengths ... is measuring the wrong thing. Your reactions don't correlate in distance (car-lengths), the

• giantg2 4y ago
  "Always measure your safety buffer in the appropriate metric: time." Distance is the appropriate metric when you want to keep two objects a minimum distance apart. Your response is only half the equation, then stopping performance comes into play. So while reactions are measured in seconds, you're converting those into distance traveled. Measuring in following time is just a convenience for eliminating distance estimation biases. That time will also fluctuate based on the road conditions and vehicle performance.