The Central Reserve: Exits and U-Turns

On a dual carriageway, the two directions of travel are separated by a central reserve — a physical divider rather than a painted line. Grass, kerbing, a barrier, or a raised strip, but in every case a structure you cannot legally or safely cross.

That single fact settles a question drivers get wrong regularly: where may you exit, or turn round?

Only at a designated gap in the reserve. Exits from the carriageway, including U-turns, are located at breaks deliberately built into the divider. Not wherever the barrier happens to be low. Not across a worn patch of grass that other vehicles have clearly used. At the gaps, and nowhere else.

[DIAGRAM: central-reserve — see SVG below]

Why the rule is stricter than it looks. A dual carriageway is engineered on one promise: that nothing will ever come towards you. Every design decision downstream depends on it — the higher speed limit, the absence of a yellow centre line, the fact that you can overtake without checking for oncoming traffic at all. A vehicle crossing the reserve at an undesignated point breaks that promise for everyone travelling at a speed the promise justified.

The designated gaps exist precisely so the manoeuvre happens where the road has been built to expect it — with sightlines, with space to wait, and where the traffic you are joining can see you.

Missed your exit? Continue to the next designated gap. The additional minutes are cheaper than any alternative, and this is the same arithmetic as the overtaking lesson: the time saved by a dangerous manoeuvre is almost always smaller than it feels.