Just drove up the M1 from London to J17 and back.
I can see why in theory Smart Motorway is a good idea. By constantly changing the speed limit, traffic can be kept following (albeit at a slower pace than usual) rather than having everyone drive at 70mph and then screech to a halt. And this part actually works OK (eesh).
The issue is with the roadworks. The 50mph speed restrictions appear to be a different layer of signage, marked with simple temporary metal signs (not gantry-based digital signs).
The combination of both can be quite confusing.
At one point, there was an NSL sign marking the end of a 50mph restriction due to roadworks. It was virtually leaning against the base of the gantry near the outer lane. The gantry itself was showing 60... so there were a 60 and NSL signs side-by-side. Should have taken a photo...
Of course I understand that they meant to say that the roadworks speed restriction is replaced by a Smart Motorway speed restriction... but you do have to constantly check and adjust your speed when driving through these bits. Not great fun when you spend a couple of hours driving (and even less so when the weather is bad).
Incidentally, while everyone was slowing down for the gantry speed limits, the roadworks ones was generally ignored with only a handful of cars (myself included) actually slowing-down to 50 mph. I should add that the lanes were at their normal width and there was no workforce in sight, so driving at 70mph would have not felt unsafe. I suppose that the physical metal signs cannot be easily removed and reinstated so they are just left there for the duration. And it seems that drivers smartened-up to the fact that the speed cameras only adjust to the Smart Motorway speed limits, but apparently not to the roadworks speed limits (unless there are specific temporary cameras for the roadworks...).
I think that in the first instance the roadworks speed limits should be incorporated into the Smart Motorway system, so that there's only one set of signs (on the gantries) controlling speed on a given stretch of road.
Then, those of us with connected cars, should have the option of having the temporary speed limit downloaded to the car's speed limiter automatically, so that it is adjusted as you drive under the gantry (or rather, as you are approaching it).
A combination of Distronic and automatically adjusted speed limiter will ensure safe sailing through Smart Motorway speed restrictions and roadworks.
Of course once all cars are fully autonomous, new possibilities will become available... including computer managed traffic that connects to all cars and provides routes and speed data.
But until then.... watch those gantries.