The 3-second rule is one of the simplest tools taught in K53 training: pick a fixed point on the road — a sign, a bridge, a pothole — and count the seconds between the car ahead passing it and you reaching the same spot. If it's less than three seconds, you're following too closely. What makes this rule useful is that it automatically adjusts for speed: the faster you're going, the more distance three seconds represents, so you don't need to memorise different following distances for town driving versus highway driving. In poor visibility, rain, or when following a large vehicle that blocks your view ahead, many instructors recommend extending this to four or five seconds.
Source: K53 Defensive Driving Manual
Frequently Asked Questions
How do I measure the 3-second rule while driving?
Watch the vehicle ahead pass a fixed point, then count 'one-thousand-one, one-thousand-two, one-thousand-three' — if you reach that same point before you finish counting, you're too close.
Should the following distance change in the rain?
Yes — wet roads reduce tyre grip and increase braking distance, so many instructors recommend doubling your following distance in rain.
Does the 3-second rule apply in city traffic too?
It does, though in slow, stop-start traffic it's often impossible to maintain a full three seconds — the key is closing the gap only when it's genuinely needed, not sitting on the bumper ahead of you.
Why not just use a fixed distance in metres instead?
A fixed distance doesn't scale with speed — the gap that's safe at 40 km/h is far too short at 100 km/h, which is exactly the problem the time-based rule solves.