Crash barriers should offer some protection to both the motorist and the Pedestrian where possible. Only the cyclist is not fully catered for in this instance.
Sometimes (but not often) they get it right as in this case alongside a footway, which in turn is alongside the A20 between Ashford and Charing. The state of the footway leaves a lot to be desired.
At a cross-roads in Charing, On this side of the A20 (which passes through the village), and at the mouth of the road to Pluckley. There are similar crash-barriers on each corner, which are actually placed to protect pedestrians ~ must have been a different engineer from their normal; fellow. Why at one place and not at so many others?
A different vantage point clearly illustrates that Highways can get it right, even if they didn't mean to at the time. This section of barrier on the A2070, offers protection to pedestrians, cyclists, and motorists. Whilst most of the rest of the barriers don't protect the most vulnerable in our society.
Protecting cyclists with a barrier in not a new idea:-
This picture shows a continuous barrier which is designed to protect cyclists and pedestrians, and why not? Photograph taken in Carnot-Plage, southern France. in 1998.