It took me some getting used to living in Malaysia. I'd pull out and my wife would calmly say, "you're on the wrong side of the road"...ooops. A couple times, early in the morning driving to work, still dark, I'm looking at a car coming the other way thinking "why is he on my side of the road.....S**T !!! " swerve......oops. It's kind of weird at first.
Yeah. When there's traffic around it's a lot easier to remember.
Having driven all 4 combos of righthand/lefthand roads and cars, I've noticed a couple of funny things ....
For some reason, I continue to mix up the windshield wiper control and the turn signal when first swapping from left hand drive to right hand drive or vice versa. Signalling a turn with the windshield wipers is a common problem. Other US expats in Japan tell me they have the same problem, as have UK visitors to USA.
Left and right isn't really how we think when driving. There's the "easy turn" (right turn in USA, left turn in UK/Japan, etc.) and then there's the "hard turn" across traffic (left turn in US, right turn in UK). When a UK visitor in the US tells me to turn "left", he usually means right.
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IIRC, Sweden did the big shift from driving on the left to driving on the right back in the 70's. Lots of sign changes, a bit of remodeling on various freeway interchanges, and lots of initial confusion. I think they shifted in the middle of a weekend and intially had a very, very slow speed limit throughout the country, with the speed limit being raised back up to normal over a week or two.