Late merge onto a busy dual carriageway
You are waiting at the top of a slip road joining a three-lane dual carriageway where the limit is 100 km/h. Your car is a small hatchback with four adults aboard and a full boot. The slip road is short, about 150 m from the give-way line to where it ends. Traffic in lane 1 is dense and moving at roughly 80 km/h, with gaps of two to three car lengths. A lorry is approaching in lane 1 about 200 m back, and a saloon behind it is indicating to move into lane 2 but has not yet done so. Your view up the carriageway is partly blocked by a high crash barrier on the left of the slip road. You have already selected second gear and are doing 40 km/h with about 100 m of slip road left.
1. Explain how you would build speed and choose a gap, and why the lorry's position changes your plan.
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The slip road is short and the car is heavy, so acceleration will be modest. I would use the remaining 100 m to accelerate firmly in second and then third, aiming to reach at least 80 km/h so my speed matches lane 1 rather than forcing others to brake. I would not aim for the gap directly beside me; with two-to-three-car-length gaps at 80 km/h that is too tight for a loaded hatchback. Instead I would look further ahead for a larger gap, and use the lorry deliberately: it is large, slow to change speed and easy to see, so tucking in behind it gives a safe following distance and a predictable neighbour. The saloon indicating into lane 2 is useful because it may open space in lane 1. I would signal right early, keep checking the right mirror and blind spot, and be ready to stop at the give-way line if no safe gap appears rather than barging in.
2. The crash barrier blocks your view of lane 1 until you are part-way up the slip road. How should this affect your observation and your speed?
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A blocked view means I cannot treat the first clear glimpse as a full picture. I would adjust my body position and use the slip road's curvature to get the earliest possible angle into lane 1, checking the right door mirror repeatedly rather than once. Because traffic may be hidden until late, I would delay committing to full acceleration until I can actually see a gap, keeping enough speed to merge but enough reserve to stop. If a vehicle appears suddenly in the blind area, my lower speed gives me time to lift off and slot in behind it. I would also watch the lorry's indicators and the saloon's movement, since other drivers' signals give information my mirrors cannot. The principle is that restricted visibility demands slower commitment and more frequent checks, not a single optimistic glance.
3. Halfway up the slip road you realise the gaps are closing and you may reach the give-way line at low speed. What is the safe sequence of actions?
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I would stop trying to force a merge and plan to arrive at the give-way line under control. That means easing off, possibly changing down, and preparing to stop with the handbrake if necessary, while continuing to signal right. At the line I would wait for a gap I can accelerate into, then use first and second gear to build speed quickly, accepting that I will join more slowly than ideal and must pick a generous gap. I would not cross the line and crawl along the hard shoulder or the edge of lane 1, because that is both unsafe and likely to be treated as poor lane discipline. If the traffic is genuinely too dense, waiting is the correct choice; a missed gap costs seconds, whereas a forced merge at 40 km/h into 80 km/h traffic risks a serious collision.