Could a 1-second delay in a driver's reaction at the speed limit on an expressway increase the stopping distance by several dozen meters?

The question is about a 1-second delay in the driver's reaction at the speed limit on an expressway. Such a delay may increase the stopping distance by several dozen metres. The answer is: yes.

The Road Traffic Act sets the speed limit for a passenger car on a dual-carriageway expressway at 120 km/h, and it requires you to drive at a speed that ensures control of the vehicle. The calculation is simple: 120 km/h is 120 000 m in 3600 s, that is about 33 m per second. Every second by which you start braking later - because you were looking at your phone or the navigation, or talking - means an extra 33 m travelled at full speed before the brake even starts working; on top of that comes the normal reaction time and the braking distance itself, on an expressway over 70 m. On an expressway 33 m is the length of several cars: the difference between stopping before a traffic jam and crashing into it. That is why at high speed attention focused on the road is worth more than anywhere else, and the following distance from the vehicle in front in metres should be at least half your speed in km/h, which here is 60 m.

Legal basis: Art. 20 para. 3 point 1 letter b, Art. 19 para. 1 and para. 3a of the Road Traffic Act (Prawo o ruchu drogowym)