Overtaking a Slow Truck Before a Curve on a Wet Highway
You are driving a passenger car on a two-lane rural highway outside a settlement, one lane in each direction, posted limit 90 km/h. Ahead of you a heavy truck is travelling at about 55 km/h. You have been following it for several kilometres. The road surface is wet after light rain, and your car has ABS. There is a solid line on your side approaching a right-hand curve about 150 m ahead. A vehicle is visible in the oncoming lane about 300 m away, approaching at a normal speed. Your speed is 55 km/h and you are in fourth gear. You estimate your car needs about 6 seconds to complete the overtake and return to the right lane.
1. Should you begin the overtake now? Identify the specific factors that decide this and explain how they combine.
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No. Three independent constraints each point the same way:
- Marking and sight distance. The solid line begins soon and the right-hand curve limits forward visibility. Overtaking across a solid line and into a blind curve is prohibited regardless of how clear the moment looks.
- Time-distance budget. The oncoming vehicle is ~300 m away. If it travels at, say, 80 km/h (≈22 m/s), it covers that gap in under 14 s. Your overtake needs ~6 s plus the time to close from 55 to a passing speed and pull back in - the margin shrinks fast, and any hesitation (truck speeding up, gear change) eats it.
- Grip. Wet asphalt lengthens braking distance and reduces the margin for a abort. ABS helps with steering control under braking but does not shorten stopping distance on a wet surface.
Decision: stay behind, reduce the temptation to close up, and wait for a straight section with broken line and confirmed clear oncoming lane. If you must abort mid-overtake, brake firmly and return behind the truck rather than completing into the curve.
2. Suppose you decide to wait. Describe how you should position and drive behind the truck to keep your options open, and what you should watch for.
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- Keep a following gap of at least 3 seconds in dry conditions; on wet road extend to 4–5 seconds so you can see past the truck and have room to brake if it slows suddenly.
- Do not tailgate to 'peek' - it blocks your view and removes escape space. Offset slightly to the left within your lane where legal, to improve forward visibility without crossing the centre line.
- Watch the truck's brake lights, indicators, and any load shift; heavy vehicles slow markedly on curves and may straddle the centre line.
- Monitor the oncoming lane continuously so that when a genuine gap appears you already know it is clear.
- Prepare for the overtake: select the appropriate gear in advance so acceleration is immediate, but do not begin until line and visibility permit.