i'm not sure but i think you could also store the direction of each road in a skill, maybe an angle, like:

my.DriveDirection = 0

then when the player vehicle is driving on it, you could do something like:

if(playerVehicle.pan>my.DriveDirection+20 || playerVehicle.pan<my.DriveDirection-20)
error("YOUR DRIVING THE WRONG DIRECTION");

just an idea.. idk if it helps

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