A 45-Metre Gap at 118 km/h and an Exit in 1.5 km
You are driving a seven-seat MPV with four adults and luggage on the Abu Dhabi-Dubai E11 at 06:15, in the second lane of four, with cruise control set at 118 km/h where the sign shows 120. The road is dry, but for the first 300 m after a construction-site exit a fine layer of sand lies on the surface. The hatchback ahead is about 45 m in front and is braking intermittently. A pick-up is tailgating you at roughly 15 m. Your exit is 1.5 km ahead, and the lane to its right is busy with lorries.
1. Using a two-second rule, is a 45 m gap adequate at 118 km/h, and what gap would be appropriate through the sandy section?
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At 118 km/h you cover 118000/3600 ≈ 32.8 m every second.
- 2 seconds = about 66 m
- 3 seconds = about 98 m
At 45 m you have roughly 1.4 seconds - below the two-second minimum, and worse than it looks, because your own reaction time consumes most of it. At a typical 1.5 s reaction you travel 49 m before the brakes do anything, so if the hatchback stopped dead you would hit it before you even began to slow.
Through the sandy 300 m you want three to four seconds (100-130 m) at this speed, or better, drop to about 100 km/h and hold a 3-second gap. The arithmetic behind that: at 100 km/h (27.8 m/s) with 0.7 g dry grip you need about 42 m of reaction plus 56 m of braking, roughly 98 m; on a sand film at 0.4 g the braking component nearly doubles to about 98 m, giving a total near 140 m.
2. How do you manage the tailgating pick-up and still make the exit safely?
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Treat the two problems separately.
The tailgater: the worst response is a sharp brake. Open the gap ahead gradually by easing off the throttle so your speed falls slowly - this simultaneously increases your distance to the hatchback and does not flash brake lights at a driver only 15 m behind. Where it is safe, move right out of the faster traffic, but do not let a pick-up at 15 m stampede you into a rushed lane change.
The exit: mirror, indicate, shoulder check, and begin the lane change from about 800-1000 m out at this speed, so you are settled in the exit lane well before the gore area. The busy lorry lane means you need the gap identified early, not manufactured at the last moment.
If you miss the exit, continue to the next one. Reversing, or cutting across the gore and the chevron markings, is illegal and is a classic high-speed collision.