Road rails SUCK! The first job of a track barrier is to keep the car in the lane! They do not do this. They are nothing but ramps. Just what you need when you're barrelling down the straight, is to have another car appear out of nowhere right in front of you! Now you have 2 broken cars and one of them was an innocent.
Boards work OK but open ends should have protectors installed. Grazing a barrier should Not result in a broken car. All one needs to do is pay attention to details. PVC with external joiners is one of the worst ways to go... What ever is used, it should do a good job of containing the cars!