In a game design mentality, you would instead switch them with a explicit crossover having unique signage so there would be a memorable moment, and other indicators or challenges that will clearly (and safely) shake them out of the former driving mode.<p>For example, there could be roadway exits or green arrows on the customary side for the driving direction, fake parked cars on the other side of the street, lights that flash like runway lights to simulate traffic and even a "challenge" intersection where there is no oncoming traffic (or warning sign!) on the former driving side. Vehicles that do enter the wrong side of that intersection could trigger lit in-roadway arrows that direct the mistaken driver to enter a center lane to merge.