It is something of a mystery that the rule which dictated left-turning cars gave way to traffic turning right has survived for 35 years.
Its reversal tomorrow will mean the end of a practice that is an oddity internationally and was the cause of an occasional confusion that far outweighed the supposedly more efficient movement of traffic. Probably, it endured simply because it seemed too much trouble to do away with it.
Credence for this belief was reinforced by a Herald survey this week. More than half of the 67 people questioned made at least one error in identifying which car should give way when they were presented with three test situations. Is it, therefore, only asking for trouble to change something that New Zealand motorists, at least, had become used to?
Time will surely show this concern has been overstated. The rule change has been flagged for the best part of six months, and well advertised more recently. Even ill-founded predictions of mass confusion have played a useful part in drawing attention to the changes and ensuring people can cope.
Most of all, any initial irritation arising from ignorance or misinterpretation of the rules by a few drivers will be minor compared with the likely long-term benefit. When Victoria made similar changes 19 years ago, there was a 7.1 per cent reduction in crashes at intersections. That suggests motorists will find the rules that apply from tomorrow more user-friendly. The change is overdue.