Britain has four types of motorway. Most controversial are “all lane running” motorways: no hard shoulder, only lay-bys for breakdowns. We also have “dynamic hard shoulder” motorways, which have a hard shoulder, but overhead gantry signs sometimes tell you to drive in it. They also have emergency lay-bys. I call these “smart” motorways, following everyday parlance.
Conventional motorways have a continuous hard shoulder. Controlled motorways are like conventional motorways but with overhead gantries that set compulsory lower speed limits when traffic volumes are high.1
Getting rid of the hard shoulder is extremely controversial because from time to time people die when a broken down car cannot reach the next lay-by, and their car is hit from behind. It seems common sense that hard shoulders are necessary.
In fact smart motorways save lives because most motorway collisions are between moving vehicles. Putting some vehicles on the hard shoulder spreads them out, meaning fewer crashes, and more importantly makes remaining crashes less severe. If you have 50 metres to brake from 70 mph, the Highway Code tells me you will hit the car in front at 55 mph. If you have 75 metres, you will hit it at 37 mph - a much less severe crash. Spreading cars into an additional lane saves lives. That explains why when a motorway is changed to one of these types, safety data improves.
It would be bad for safety to take a driving lane out to reinstate the hard shoulder. It would worsen safety by bunching up the cars. It would also increase journey times - leading more people to use alternative non-motorway routes. This would worsen road safety, since motorways are 7 times safer than other (non-urban) roads. For safety reasons we want to get people onto motorways, not drive them off.
We could widen motorways by adding a hard shoulder. Redoing bridges, widening gullies, altering junctions is very expensive as well as having bad implications for biodiversity. It won’t happen, and it shouldn’t happen.
That does not mean that we should ignore legitimate worries about being stranded, and hit from behind. I offer three proposals.
First, a 50 mph speed limit in the left lane on smart motorways. When there is little traffic no-one will use the left lane, and it will (de facto) become a hard shoulder. When the motorway is busy enough to create safety and speed benefits from driving on the hard shoulder, it will happen automatically. When the motorway is empty enough that this is unnecessary, it becomes a hard shoulder.
Second, lorries should be banned from the left lane on smart motorways. This means that cars that break down and cannot get to a lay-by will not be hit by a lorry.2 Being hit by a car is much less bad because they are much lighter, and because cars are designed to absorb force in a collision. The lower speed limit will also reduce collision severity.
Finally, cars should always be allowed to drive on all hard shoulders, but only up to 30 mph and only if they are coming off at the next exit. All of us have been stuck on a motorway in sight of our exit. The ban on using the hard shoulder in such circumstances is pointless: it is safer to do 30mph on a hard shoulder than on a conventional road. No child will run out in front of you. No-one will reverse out of their drive, or pull out of a side road.
Obviously all of these ideas should be piloted, tested and evaluated. That is the only way to tell if they affect actual safety. If they improve perceptions without harming reality, we can increase the number of smart motorways. That would save lives, and reduce travel times, compared to maintaining congested motorways in a conventional format. My third proposal would simply cheer people up, shorten journey times, and reduce emissions.
Strictly speaking controlled motorways are also smart, but I don’t think that is how most people use the term.
Lorries would be given a quarter of a mile to move out of the left lane on joining, wherever possible that section of the motorway should be given a continuous hard shoulder. Moving out a lane is no harder than joining a motorway, so I am confident that the lorry can manage this. Similarly they would be allowed to move back shortly before a junction, if they are turning off.
My only comment on this is to observe that Highway Code stopping distances are out-dated and do not reflect modern cars/tyres.
The Highway Code lists the 70mph stopping distance as 96m, made up of 21m “thinking distance” and 75m “braking distance”.
In reality most modern cars will do the braking distance from 70mph in 45-50m. The overall stopping distance in the Highway Code are probably 25% too long.
Moreover the “real world” distances are going to get ever closer to the test distances, thanks to widespread adoption of things like auto brake distribution, brake assist (which applies 100% brake force whenever the driver rapidly brakes to 80% or more), and even collision pre-sensing (which is increasingly common).
I don't agree with everything in this post. You say 'Putting some vehicles on the hard shoulder spreads them out'. But that won't happen. Where there is all lane running the hard shoulder is frequently empty now, as many drivers don't want to use it. Where there is a hard shoulder plus three normal lanes the left hand running lane is likewise largely empty as drivers congregate in the middle lane at 50-60 mph. You have to start with better lane discipline, which means enforcement, but police vehicles are almost absent from motorways now. Your proposals will only work if people understand them and act on them, which they won't I'm afraid