Strangely Brown wrote: I certainly feel far less safe on them.
Feeling safe doesn't mean you are safe. Risk compensation, etc.
Strangely Brown wrote:a "Smart" motorway will have an immovable concrete barrier or armco on the left edge.
Concrete on the nearside will typically be around obstacles such as bridge piers. Personal opinion is that this is for protection of the infrastructure from terrorism is slightly more important than safety of road users.
Concrete is more typically used for central barriers as they're better at resisting crossovers.
Strangely Brown wrote:A DC will more often have a "soft verge", drainage stones or an embankment. The point being that there is somewhere to go in an emergency.
Safety issue here is that run-off crashes, likely to be at high speed, so high potential for KSIs.
Everything's a trade-off.
Your 'standard' is how you drive alone, not how you drive during a test.