All-lane running is the reverse: the hard shoulder is completely missing and you have to just hope that if you break down and can't make it to a refuge bay that a camera operator notices your car stationary in the lane, which is still going at full speed, and closes the lane before someone hits it.
In personal experience of coming up on stopped cars in live lanes, with no signed warning of any kind, they aren't noticed immediately. A stationary vehicle in a lane comes appears very quickly when the lane is moving at 55-70mph.
Typically (here in Italy) the normal lanes are 3.25 to 3.75 meters wide while the emergency lane is 2.50 to 3.00 (it depends on the period the highway was built, I believe)
So you need to change horizontal lines/signage and make all lanes, including the hard shoulder/emergency lane, the same width, and this means that in "normal" operation travel lanes will be narrower.
On paper, sure.
In practice it's the worlds best passing lane because the drivers who make the left lane useless as a passing lane don't self select to use a lane that's narrower than the rest, has a ton of merging traffic and a barrier on the harder to see side of the vehicle.
Smart motorways are unpopular because they typically include a lot of speed enforcement cameras and lower speed limits, so you can no longer zig zag through traffic at 90 miles an hour.
Thus, smart motorways, pollution enforcement zones, and neighbourhood traffic charging schemes are very controversial. The same people who got exercised about face masks will cross the country to protest them.
These people are the base of the current government, which needs a culture war as the real issues look unwinnable right now so the civil service are under pressure to find a reason to roll this stuff back.
* controlled, which have a permanent hard shoulder, but use technology such as variable speed limits to adjust traffic flows
* dynamic, where the hard shoulder can be opened up at peak times and used as an extra lane; when this happens, the speed limit is reduced to 60mph
* all-lane running, where the hard shoulder has been permanently removed to provide an extra lane; emergency refuge areas are provided at regular intervals for cars that get into trouble
https://www.bbc.co.uk/news/uk-65288852
IMO there shouldn't be any objections to "controlled" smart motorways. All lane running is idiotic; dynamic running is OK but I would say that the speed limit needs to be lowered from 60 mph.
As an aside: British drivers have terrible lane discipline on motorways ("middle lane hogging"), which eats up road capacity for no good reason. There's plenty of variable message signs on motorways - they should display "Keep left unless overtaking" if there's no other message to be displayed.
Also there are vague electronic signs saying "reports of obstruction", "report of blocked lane" or "reports of pedestrians" with no further actions (like a lane closure) maybe twice a week. There very rarely actually is an obstruction to be seen in the end, so the signs get ignored, even when there is an actually dangerous hazard like a car in the middle of a lane.
> British drivers have terrible lane discipline on motorways
They certainly do. They even made it illegal a few years ago, but it's virtually never enforced. For a start, there aren't very many road police to enforce it.
A small but significant number of people also completely disregard the red X markers and zoom down closed lanes towards, presumably since they don't usually do the red X for fun, a broken down vehicle or accident. This is very much illegal (though it's only a £100 fine), but again seems not to be enforced sufficiently to prevent it.
Rule 268 of the Highway Code touches upon this:
> In congested conditions, where adjacent lanes of traffic are moving at similar speeds, traffic in left-hand lanes may sometimes be moving faster than traffic to the right. In these conditions you may keep up with the traffic in your lane even if this means passing traffic in the lane to your right. Do not weave in and out of lanes to overtake.
Ashley Neal's video on motorway driving provides some good examples of when sticking in lane 2 is OK, provided that you continuously observe and anticipate other road users: https://youtu.be/Vo7sNwf80lI?t=766
1. Government adds more safety equipment to some test Motorways which allows monitoring lanes and separately varying limits per lane. Unsurprisingly this makes these motorways safer, let's say a factor of X.
2. Government converts hard shoulders into running lanes to save money on some test Motorways. Unsurprisingly this makes motorways more dangerous, let's say by a factor of Y.
3. Government argues that X/Y > 1, therefore adding safety equipment and converting hard shoulders into running lanes, would be on net an improvement. Conveniently the fact that they're doing this because it's cheaper is not mentioned.
We don't accept this sort of arithmetic in other contexts and we shouldn't here. Maybe adding safety equipment is too expensive to justify the reduced danger, but moving to all-lane running is unacceptably dangerous, so, you can't do that, regardless of whether somehow then the safety equipment is magically free.
Previous governments have chosen not to take up obvious safety improvements because they were too expensive. For example, trains in the UK all have the very simplest and oldest SPAD-prevention, the Automatic Warning System, which is activated by an electromagnet (well, technically a magnet which is deactivated by an electromagnet so as to fail safe) but doesn't distinguish between Danger (do not pass this signal) and Caution (expect to find the next signal at Danger) so drivers can get into a bad habit of reflexively cancelling it since they need to pass Caution signals on many routes all the time. Government could have required Automatic Train Protection, a more sophisticated but expensive system which was demonstrated on a small fraction of UK lines and they elected not to spend that money to do the rest. Today most passenger trains have TPWS (which is cheaper than ATP but fairly effective) and a few newer ones are starting to do ETCS (the European system which obviously has production scale benefits, you're buying off the shelf gear that's sold across the continent).
On the other hand, unlike not making them safer, making the roads more dangerous is clearly just a bad idea, and so it became politically harder to defend this practice, hence Rishi now scrapping it.
The "Smart Motorway" has signs to turn this refuge into a full speed lane, leaving a couple of feet for the breakdown area.
I never understood how this could be approved by any Minister who wanted to retain their position, but I guess saving money on new road lanes is more important than the lives of the voters and their families.
Smart Motorways also try to slow traffic on approach to a bottleneck to ease the arrival of congestion before it brings the road to a standstill. In practice, drivers ignore the signs unless they have a speed camera attached to them, making the investment in the technology mostly useless.
Good riddance to this dangerous idea. Don't revisit it while cars have organic drivers.