Overtaking a Slow Tractor Before a Crest
You are on a two-lane road outside the city with a solid centre line on your side for the next stretch. Ahead, a tractor with a wide implement is travelling at about 25 km/h. You are doing 80 km/h and have been closing on it for some time. The road runs straight for about 200 m, then rises to a crest and curves gently right. There is a broken centre line beginning roughly 60 m ahead of you, and a road sign indicates a junction 300 m beyond the crest. A car is visible in your mirror about 150 m back, and you cannot see beyond the crest. Your car accelerates from 80 to 100 km/h in about 9 seconds.
1. Assess whether an overtake is possible here. Break the manoeuvre into distance and time and state the decision.
Read the worked answer
Do not overtake. The decisive fact is the crest: you cannot see oncoming traffic beyond it, and a junction 300 m past the crest adds the chance of a vehicle emerging or turning.
Rough arithmetic. To pass a tractor doing 25 km/h while you travel at 90–100 km/h, your closing speed is about 65–75 km/h, or roughly 18–21 m/s. You need to cover the tractor's length plus your own plus a safe return gap - say 25–30 m of clear road alongside. That is only about 1.5 s of overtaking time, which sounds easy. But the real constraint is the sight distance: you must be able to see the whole overtake plus a margin, and you cannot see past the crest at all. If an oncoming car appears over the crest at 90 km/h while you are alongside the tractor, the combined closing speed is around 180 km/h, or 50 m/s, and neither driver has anywhere to go.
The broken line starting 60 m ahead permits overtaking; it does not make it safe. Line markings are a minimum condition, not a guarantee. The correct decision is to hold back, keep a following gap of at least two seconds behind the tractor (more, because the implement may swing), and wait until you have a clear view past the crest and past the junction.
2. The driver behind you is tailgating and has begun to move out as if to overtake you and the tractor together. What do you do?
Read the worked answer
Your job is to be predictable and to avoid being part of someone else's bad overtake.
- Maintain a steady speed and hold your position in the lane; do not accelerate, brake sharply, or drift left to block him.
- Increase your gap to the tractor slightly, so that if the car behind pulls out and then has to abort, there is space for him to drop back in front of you rather than alongside you.
- Do not follow him out. A second vehicle overtaking on a blind crest doubles the exposure.
- If he commits and an oncoming vehicle appears, do not flash, swerve or sound the horn in a way that adds confusion; slow down and open space so he can return to the lane.
The reasoning is that a tailgater who pulls out is now in the most dangerous position on the road. Your best contribution is to give him a gap to retreat into and to keep your own sight line and stopping distance intact.