Vegetation can be used as crash cushions. For instance the Roads and Traffic Authority of New South Wales write that frangible vegetation in the median provides the following benefits: “Can screen headlight glare” and “Provides a crash cushion effect” (Landscape Guideline 2008) .
Below is an example of planting on an Australian freeway where plants are used on the approach side of a bridge pier. The location is the Conroys Road flyover of the Western Highway. All sourced from https://maps.google.com.au/
Note: In Australia driving is on the left hand side.