The idea behind so-called 'smart' motorways is that by varying the rules according to traffic flow, congestion is reduced. Users of the circular car park we know as the M25 will be familiar with signs on the gantry that set different speed limits at different times. 60 means no more than 60 mph but in practice means 40mph. 40 means no more than 40 mph but in practice means slow down to a crawl, stop, crawl forward, stop, etc. I haven'tseen any noticeable reductions in congestion.
Another feature of smart motorways that the traffic planners have come up with is to open up the hard shoulder to allow it to be used as a lane when traffic is heavy. Motorists are not comfortable with this, either because old habits die hard or because they don't trust the logic. In practice many do not use the opened-up hard shoulder, thinking that a blank gantry sign above it means the lane is closed. (A big red cross means a lane is closed, but some motorists seem not to know that either).
Hard shoulders have always been useful as a clear way for emergency vehicles to reach an accident. The deicision to fill them with traffic is not only bizarre, it has had tragic results. Four people in 10 months have been killed by vehicles on the hard shouder of the M1. A big red cross that would warn oncoming traffic that the lane is obstructed by a broken down vehicle will only appear if the vehicle occupants have managed to reach an SOS point. Have you noticed how far apart such points are, and how little information there is as to where the nearest one is? The whole thing doesn't seem so smart to me.