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Analysis | Smart has to mean smart for all-lane running motorways

M4 smart motorway scheme in operation

It’s difficult for the engineering community to know what to make of the concept of the “Smart Motorway”.

On the one hand, any self-respecting highways engineer ought to appreciate a traffic intervention that provides a 33% boost to capacity for a 60% lower cost than a traditional road widening scheme. On the other hand, most diligent designers would be unable to ignore stakeholder concerns about the impact all-lane running has on motorway safety, or claims that it increases congestion, and by extension carbon emissions, on the surrounding road network.

The smart motorway concept involves adding extra lanes to motorways by upgrading hard shoulders to carriageway standard. These sections of motorway are controlled by variable message speed limit signs but have no hard shoulder, other than occasional stopping bays.

Just how divisive the concept has become was in evidence again when the cross-party Commons transport select committee recently invited written submissions for its inquiry into the success of the all lane running schemes on sections of the M25, M1, M4, M5, M6, M42 and M62. As reported in New Civil Engineer, the Metropolitan Police is among those stakeholders to express reservations about the safety of Smart Motorways. It told the committee that there was “clear evidence” of a “significant” rise in reported near misses on sections of the M25 where the hard shoulder has been used for running traffic.

Like the Automobile Association (AA), the Metropolitan Police approaches the smart motorway debate from a different angle to some of the other stakeholders consulted by the committee. Both parties are justifiably concerned about the safety of drivers whose vehicles have broken down in the hard shoulder, the safety of operational staff attending roadside breakdowns and the ability of emergency services to reach major incident scenes.

 “The Metropolitan Police was among those stakeholders to express reservations about the safety of smart motorways.”

Ranked against them are the views of those who have the most to gain from the cost-effective introduction of all lane running. The Department for Transport’s submission understandably celebrates the improvement in average journey times for road users on the M25 while drawing a different conclusion about the safety figures. It references accident data from Highways England’s evaluation of the first 12-month operational period of the M25 smart motorway schemes. This claims overall collision and casualty rates for the two schemes on different parts of the motorway have improved, with no fatalities attributed to all lane running during that time. In mitigation, it admitted that there was an increase in recorded serious collisions on the smart motorway section between junctions 5 and 7 of the M25, although it contends that none of these were directly related to all lane running.

So where does the balance lie in the argument? The reality is, it’s probably too soon to say. The Department for Transport acknowledges that although initial results from the M25 scheme are promising, a further two years of validated data is required before the results can be considered conclusive evidence. But regardless of the outcome of this research, it ought to accept that some of the issues raised to the select committee cannot be ignored.

The nub of the safety concerns aired by the Metropolitan Police and the AA is that the danger presented to life of a broken down vehicle in the left hand lane when traffic flows are light and visibility is reduced, is too great to accept. Both make the point that Highways England’s Motorway Incident Detection and Automatic Signalling system (MIDAS) does not detect queues when traffic flow is light and therefore would not register the presence of a broken down vehicle as slowing traffic in such a situation and set a variable mandatory speed limit (VMSL) to prevent a collision.

That the hard shoulder would be in use at all and not available as a safe refuge in an uncongested scenario points to one of the fundamental failings in Highways England’s smart motorway roll out. If all lane running is deemed to be safer in times when traffic flow is high, and unsafe in times when traffic flows are low, surely we need our motorways to react more dynamically to traffic conditions. Indeed, for a motorway to be described as truly “smart”, shouldn’t it have the intelligence to open and close lanes and communicate messages about potential hazards to drivers more effectively?

We live in a digital age where instant access to data regularly enables people to make smarter, more informed choices about the world around them, so it should not be beyond our engineers to design a motorway system that warns motorists and directs traffic in the event of an accident or congestion. The Department for Transport acknowledges as much in its submission to the committee, saying a key challenge for the government and Highways England in the future will be to drive forward changes and developments such as assisted driving technologies and autonomous vehicles alongside smart motorways to maximise their potential.

Highways England submits that it has saved significant amounts of money by employing all-lane running to extend motorway capacity – we also know it has some £15bn to spend on England’s motorway network and trunk roads. Perhaps now is the time to earmark some of that money to develop a solution that really puts the ‘smart’ in ‘smart motorway’.

Readers' comments (2)

  • What is missing from the above analysis is the fact that the hard shoulder, although safer than a stopping in a live lane, is still a highly risky environment. Many people are seriously injured and there are a number of fatalities on the hard shoulder each year. Unfortunately, something like 80 to 90% of stops on the hard shoulder are illegal and the fact that such illegal behaviour is much reduced on All Lane Running is one reason why safety improves when ALR is implemented and the hard shoulder is converted to a running lane. The residual and understandable concern about the low proportion of vehicles which are unable to reach an Emergency Refuge Area and stop in a live lane is being already being addressed through stopped vehicle detection technology which I believe is currently being trialled on two motorways.

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  • Think perhaps of Almondsbury Interchange, (M4/M5) , complex for drivers even in the 1960's. The net says "Unusually within the UK motorway system, this forces multiple lane changes for vehicles traversing some of the routes."
    Is it any easier as a managed Motorway? The regulars may be in the majority and able to delete the navigation issues and enjoy the flow on autopilot. The holiday maker and similar first-timer has all the 1960's navigation issues And the 21st century off-road distraction of gantry speeds and lane "closure" information. What attention is left for being carved up by a late lane changer? Not surprisingly Holiday traffic is still delayed by crashes.

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