Wet night road near Mavrovo: worn tyres, glare and a cyclist with no light
At 21:40 you are driving on a two-lane regional road near Mavrovo, outside any settlement, where the general limit is 80 km/h. It has been raining and the asphalt is wet and shiny. Your car's tyres have 2.0 mm of tread left and are inflated to the pressure for an empty car, although you have three passengers and a loaded boot. Ahead, at the outer edge of your dipped beams, you notice a cyclist in dark clothing with no rear light, riding in the same direction at about 20 km/h. You are doing 80 km/h. An oncoming car about 150 m away still has its main beams on and shows no sign of dipping them. The road curves gently to the right and the shoulder is a grass verge that drops 30 cm. There is no street lighting and no other traffic for kilometres behind you.
1. Estimate your stopping distance at 80 km/h on this wet road compared with a dry road, and explain why the tyres and the load make it worse.
Read the worked answer
Arithmetic (reaction time about 1 s, wet friction around 0.45, dry around 0.8):
- 80 km/h = 22.2 m/s, so thinking distance ≈ 22 m.
- Dry braking: 22.2² ÷ (2 × 0.8 × 9.81) ≈ 31 m → total ≈ 53 m.
- Wet braking: 22.2² ÷ (2 × 0.45 × 9.81) ≈ 56 m → total ≈ 78 m.
So on this surface you need roughly 25 m more than on a dry night - and that is with good tyres and full attention.
Why your car is worse than that:
- 2.0 mm tread is close to the 1.6 mm legal minimum. Shallow grooves cannot clear water, so the contact patch starts to float and braking and steering degrade long before full aquaplaning. Wet braking on worn tyres can easily be 20–30 % longer.
- Pressure set for an empty car with four adults and a full boot means the tyres are effectively under-inflated for the load: more sidewall flex, more heat, vague steering, and a greater chance of damage on a pothole.
- Loaded car: more mass means more energy to shed, and the brakes have to work harder and get hotter.
Conclusion: around 78 m or more of stopping distance against a cyclist you only see at the edge of your beams means 80 km/h is not a defensible speed here. Wash off speed now.
2. The oncoming car keeps its main beams on. How do you deal with the glare without losing the cyclist?
Read the worked answer
Do not stare at the light. Look down and to the right, using the right-hand edge line or the verge as a steering reference, and keep the cyclist in your peripheral awareness.
Immediate actions:
- Ease off the accelerator and cover the brake - reduce speed until you can stop within the distance you can actually see, because for a second or two you are effectively blind.
- Do not retaliate with your own main beams. Two blinded drivers is twice the hazard, and flashing him is unlikely to change anything at 150 m.
- Give the cyclist room: he has no light and dark clothing, so assume his position is unstable; he may wobble as the car passes him.
- If the glare is genuinely disabling, slow further and, if necessary, stop on your own side of the road until the car has passed. Stopping is far cheaper than a blind overtake.
After the car passes: your eyes need time to readjust, so stay at the reduced speed for a few seconds rather than accelerating straight back to 80 km/h - the cyclist is still ahead and now you are the only light source he has.
Judgement point: the exam is testing whether you treat glare as a reason to slow down, not as something to endure at the same speed.
3. The oncoming car is still 150 m away. Should you overtake the cyclist now? Show your reasoning.
Read the worked answer
No. Work through the geometry.
An overtake requires lateral clearance of at least 1.5 m, time to move out, pass and return, and a margin in case the cyclist swerves.
- Your speed 80 km/h, cyclist 20 km/h: relative speed about 16.7 m/s. A pass of 2 s for the approach plus, say, 1 s alongside and 2 s to return comfortably is at least 4–5 s of time spent out of your lane, covering 90–110 m of road.
- The oncoming car is closing at 80 km/h + your 80 km/h = about 44 m/s. In 4 s the two of you cover about 180 m of the 150 m gap before you are back in lane. You would not clear him.
So:
- Reduce speed to something close to the cyclist's pace, keeping 3–4 s behind - far enough that if he falls you can stop.
- Let the oncoming car pass.
- Then check the second time: no oncoming traffic, no junction or crest, solid edge line permitting, enough clear road to complete the pass.
- Overtake with at least 1.5 m clearance, ideally more, since he has no light and may not hold a straight line.
Why speed matters here: the 150 m gap looks generous at walking pace and is nothing at a closing speed of 160 km/h. Estimating gaps in metres rather than in seconds is the classic error this scenario is built to expose.