Background research

I just want to add this link to the blog which describes already implemented the actual Speed Harmonization Signing system in Netherlands and Germany. I have never been in neither country and never heard of this system used, but according to this website they have used this system since about 1970s.

I am actually kind of shocked, but pleasantly surprised by this discovery that people already been thinking and making a huge effort in building such systems to relief the stress on the roads.