A diamond turn is a kind of turning manoeuvre used by
motor vehicles at four-way
intersections
In mathematics, the intersection of two or more objects is another object consisting of everything that is contained in all of the objects simultaneously. For example, in Euclidean geometry, when two lines in a plane are not parallel, their ...
.
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
Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...
), they should turn in a wide
arc
ARC may refer to:
Business
* Aircraft Radio Corporation, a major avionics manufacturer from the 1920s to the '50s
* Airlines Reporting Corporation, an airline-owned company that provides ticket distribution, reporting, and settlement services
* ...
that passes close to the centre of the intersection.
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.
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.
References
Driving techniques
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