Smart motorways: a dead-end?

Smart motorways have been controversial ever since their inception in 2006, when the concept was trialled on the M42 in the West Midlands. The original intentions of improving journey times, reducing emissions, increasing effective road capacity and minimising construction times and costs were pretty universally supported.

Unfortunately, safety concerns soon dampened public enthusiasm for the scheme and additional development on 11 projects was 'paused' in 2022. In April 2023 the government announced that no new smart motorways would be completed.

What are smart motorways?

Smart motorways, also known as 'active traffic management' motorways or 'managed motorways', are motorways that have been redesigned to improve the efficiency and safety of our highways. They employ a variety of measures including MIDAS incident detection technology, variable speed limits and the intermittent or permanent use of the hard shoulder as an additional running lane.

The scheme was pitched as being safe and very cost-effective. In 2007 it was calculated that smart motorway technology could be installed for £15 million per mile or less, while conventional motorway widening would take much longer and cost up to £79 million per mile.

What went wrong?

Despite near-universal support for many of the concepts that inspired the scheme, there was always a sceptical contingent who foresaw potential safety issues.

The government seemed to place a lot of faith in a Highways Agency report into the first six months of the active traffic management experiment. Journey times were reduced by a modest but significant amount, speed limits applying to the hard shoulder while it was being used as a driving lane were mostly being obeyed and there was some indication of a reduction in the overall number of accidents. Specifically, there had been no accidents caused by using the hard shoulder as a driving lane.

The Highways Agency did warn that accident statistics were usually compared over a period of three years, meaning that the figures in its report should be considered cautiously. That caveat was to prove somewhat prophetic.

The cold shoulder

One of the cost-contentious aspects - and arguably the fatal flaw in the design - was the elimination of the hard shoulder on motorways. This process began in 2006 with the introduction of the 'dynamic hard shoulder' which could be assigned ad hoc as an additional driving lane to reduce congestion and improve traffic flow.

The smart motorway scheme later included plans to change these dynamic hard shoulders into full-time running lanes, meaning that there would be no continuous refuge at the left-hand side of the motorway. Instead of a permanent lane providing a safe space for drivers in difficulty and a clear access route for emergency services, there would be 'emergency areas' at intervals along the road.

In theory, the emergency area design could prove safer than the traditional hard shoulder, but the government subsequently changed the plans so that emergency areas would be fewer in number and spaced further apart. Obviously, this made it more difficult for drivers to reach the refuges should their cars break down.

Mixed signals…

While the scheme was initially welcomed by much of the public, by some motoring organisations and, cautiously, by some road safety and environmental campaigners, drivers soon became hostile to the new arrangements.

Surveys conducted in 2022 showed that almost three-quarters of drivers avoid using the left-hand lane on smart motorways. Nearly 80% of drivers doubt they would be able to reach an emergency refuge area if they broke down and less than a quarter of drivers trust that the highways authority can detect vehicles that have stopped in driving lanes and respond promptly and appropriately.

Confusing safety stats

While there is little doubt that drivers lack confidence in smart motorways, the actual safety figures are difficult to pin down. Many different sources appear to emphasise different aspects using different methodologies in their data analysis. The objective safety or otherwise of smart motorways varies according to which metrics one uses to assess it.

For a simple overview we will refer to the government's own concise figures from its Smart motorway comparison report: December 2022.

For the purpose of the table below, the government's definitions of the various motorway types is as follows:

Controlled motorways Controlled

Controlled motorways retain the conventional motorway configuration, including retaining the hard shoulder but have additional technology such as variable and mandatory speed limits to control the speed of traffic, and overhead electronic signs to display messages to drivers. Controlled motorways alone do not provide additional capacity however in some locations controlled motorways have also been widened to provide an additional running lane.

Dynamic Hard Shoulder running motorways DHS

DHS motorways apply controlled motorway technology described above but temporarily increase capacity by utilising the hard shoulder as a running lane at peak times. DHS motorways also have emergency areas (EAs) providing a safe place to stop in an emergency, set away from the carriageway.

All Lane Running motorways ALR

ALR motorways apply controlled motorway technology as described above but permanently convert the hard shoulder as a running lane, increasing capacity. ALR motorways also have emergency areas and stopped vehicle detection (SVD) technology.

Even this 'simple' table needs a little explaining. 'Fatal and weighted index' is a figure obtained by assigning a score to the different types of injury. The government explains it thus:

If you find that too complicated or difficult to understand, just refer to the other columns. We should also bear in mind that old-style conventional motorways aren't represented in the table.

Of the types that are assessed, the full, all lane running kind of road (the one that the government wanted to develop) shows the lowest number of personal injury collisions. However, it also shows the highest incidence of fatalities.

The government has the benefit of access to and analysis of statistics for the whole strategic road network (SRN) including the conventional motorways not included in the table above. Overall, it felt justified in claiming that:

Why smart motorways ground to a halt

Regardless of what the vast mire of different and selective statistics may show when viewed from various angles, the bottom line is that people don't have confidence in smart motorways. They don't consider them safe and they do not feel comfortable using them.

In April 2023, the government finally announced that no more smart motorways would be completed. There is also growing pressure from various quarters to reinstate the hard shoulder on those roads where it has been eliminated.

Aside from the lack of public confidence in smart motorways, the other factor mentioned in the government's announcement was 'financial pressures', which seems a little surprising when one considers that relative cost-saving was one of the justifications of the scheme. Even the Daily Telegraph declared

The road ahead

Bearing in mind the 'financial pressures' mentioned when the smart motorway scheme was scrapped, it is difficult to predict what the government will decide to do to relieve congestion, improve safety and reduce the environmental harm caused by motorway driving.

As any regular motorway user will know, leaving things in their current state would not be a satisfactory option.