In this picture, I was driving down the Pali Highway and noticed that the turns are slanted. I was driving down the Pali coming from town and I noticed the big turn at the bottom of the Pali. I was slanted toward the center. They slat the highway towards the center to increase the amount of force keeping you in a circle. If you make a turn on a flat road you are using only friction to keep you moving in a circle. When you slant the curve allows you to make turns at faster speeds because you and friction and cosine of the normal force keeping you in a circle.