The number of fatal and serious-injury crashes between right-turning vehicles and oncoming vehicles at intersections has dropped by nearly a quarter since the give-way rule was changed six months ago.
Transport Agency figures for April to September show 44 such crashes compared with 58 for the equivalent period last year.
The number of injury crashes dropped from 328 to 275.
The agency says it's too soon to say definitely that the change has reduced the number of crashes, but the first six months indicate it has.
Chief executive Geoff Dangerfield says the figures justify the agency's decision not to bow to criticism that it gave drivers too little notice of the change.
He says if the advertising campaign starts too early then people start putting it into practice before the implementation date.
Mr Dangerfield says the agency's approach was to make the campaign relatively short and sharp, about two weeks ahead of time, and in retrospect that worked well.
