A diamond turn is a kind of turning manoeuvre used by motor vehicles at four-way intersections.

Details

If a driver approaches a four-way intersection and wishes to make a turn opposite of their side of the road (e.g. a right turn if driving on the left side of the road, as in the UK or Australia), they should turn in a wide arc that passes close to the centre of the intersection.^[1]

This is nowadays the standard type of driver's-side turning manoeuvre at a four-way intersection other than a roundabout. In particular, at intersections with traffic lights, it enables a traffic signal phase to allow traffic approaching the intersection from two opposing directions to both turn right simultaneously without colliding.

The diamond turn is distinguished from a historically required manoeuvre wherein drivers simultaneously turning right from opposing directions were required to turn around a silent cop in the centre of the intersection, which resulted in the two vehicles looping past one another with their driver's sides adjacent.^[1] This type of turn is still practiced at four-way roundabouts where those making a turn opposite of the side of the road must turn around the central traffic island but was eliminated from all other four-way intersections, as it requires those turning right from one direction to cross right turning traffic from the other direction.

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