I live on one of the receiving ends of a dangerous curve in the road. In the past 15 years we have had 36 accidents (most on the other end of the curve where another road comes into it at an angle). A year ago we experienced another (one of the more spectacular ones). My wife and I decided that THAT WAS ENOUGH, and waged war with the State--who never put warning signs up and posted the speed limit at 45mph (most come around the curve at at least 50mph--which is too fast for that curve that has little to no banking on it). We waged war on the Sherriff's Dept. who did not help us in dealing with this situation when asked, and thought it was funny that we even asked. We got the local TV action reporter involved. We now have signs all the way through the curve, and help from the State Patrol who now comes around periodically to keep drivers on their toes. If you live on a bad curve--do not be complacent. You may end up with a car in your living room some day. Now, to get to the point:
To prevent future speeders from being so flamboyant in their attack on our property I built two planter boxes. They are made of cinder block, topped with bricks to match the brick on the house, sitting on a concrete slab. They each have a 2.5" drain at the base. Interiors are painted with rubberized paint. Their outsides are covered with mortar in a swirl pattern, tinted to coordinate with the fence. They would be fine for any perennial plants--including daylilies. If someone decides to plow into them I doubt that they would be seriously hurt (so long as their air bags work). The rubberized paint is available from all the big box stores. I got mine from Amazon. The paint keeps the dirt away from the blocks/mortar so high pH problems are avoided.