That's why I also added a (or lower). I do not know what a safe driving speed would be. I just know its way less than the 100 KMpH that roads are usually design

That's why I also added a (or lower). I do not know what a safe driving speed would be. I just know its way less than the 100 KMpH that roads are usually designed for. Driving speed should be about equal to a leisurely human-powered bicycle speed. Or maybe lower since they have more mass, but no one's gonna agree to that. (Maybe that's a good thing?)