On 7 September, 1967, at exactly 4:50 AM, Sweden’s traffic came to a standstill. It was “H Day” – Högertrafikomläggningen, or “Switching to Driving on the Right.”
All traffic in the nation stopped, carefully changed from the left to the right side of the road, and at 5:00 AM, continued on their way. Not a single accident took place, and in the aftermath, the accident rate actually decreased.
The Old Wolf has spoken.
Playing in the World Game 
And the old joke goes like, “they decided on a gradual approach, changing sides for heavy traffic the first day, and the next day for smaller cars.” 😉