Explained: The pros and cons of smart motorways

Smart motorways dangerous

When smart motorways were introduced in 2006, the goal was to tackle stop-start congestion using variable speed limits – and in some cases by incorporating the hard shoulder as a running lane.

Another aim was a reduction in collisions, as in theory traffic can be better controlled in relation to stopped vehicles. However, this latter goal has not been achieved, leading to considerable controversy.

With help from Moneybarn, we weigh up the pros and cons of smart motorways in light of the bad press – and plans for the ‘smart’ conversion of 300 miles of motorway between now and 2025. 

Smart motorways: the pros

Smart motorways slammed in MP's report

Increasing traffic flow

The obvious way to increase traffic flow is to add lanes. So you either build them, at great expense, or you convert existing space that’s not in use to a running lane. That’s what smart motorways do with hard shoulders, with the proviso that the lane can be deactivated in the event of a stopped vehicle being detected. There are also emergency refuge areas that ailing vehicles can use.

Broadly speaking, this was successful. Highways England figures showed that journey reliability was improved by 22 percent on roads where smart conversions took place.

Savings money and the environment

The conversion of hard shoulders reduces expenditure on new lanes. That’s a saving made by the taxpayer, who would have footed the bill.

A less obvious saving is the environmental one. Better controlling traffic flow and speed, and mitigating stop-start movement, reduces emissions. It also means your car suffers less wear and tear.

Smart Motorway stopped vehicle detection doesn't always work

Hard shoulder safety was an issue anyway

One thing that’s curious to note is the safety record of non-smart motorway hard shoulders. In total, 40 percent of incidents involving a stopped-vehicle occur on a hard shoulder. 

Emergency refuge areas, properly distributed, make collisions less likely due to their being separated from the road. Vehicles are less likely to drift into them than a hard shoulder, too.

Smart motorways: the cons

Smart motorway emergency area upgrades

All-lanes-running casualties

Recent spates of casualties, crashes and near-misses involving stranded vehicles on all-lanes-running stretches have cast a shadow on the smart motorway idea. Indeed, some MPs have called for the rollout of these roads to be stopped. The AA won’t let its crews stop to help motorists until they’re towed to a refuge area.

It’s been posited this can be avoided with better stopped-vehicle detection systems, plus more frequent refuge areas. At the time of the smart motorway trials, refuge areas were four times closer together than on some later installations.

Emergency refuge areas

Which leads us into the emergency refuge area point. The consensus is that we need more of them, so that fewer people stop in-lane.

However, while you’re likely to be safer while stationary, getting back onto the road from a refuge area can be more dangerous. Hard shoulders offer more of a run-up when it comes to rejoining running lanes. Refuge areas are limited on space, and it can therefore be difficult to re-join safely, unless the lane you’re entering is slowed down.

Smart motorways slammed in MP's report

Land of confusion

Much has been made of how smart motorways are confusing for road users. “Some hard shoulders on dynamic smart motorways are only open to running traffic during the morning and evening peaks, but this catches out some drivers when their routine changes,” Highways England chief executive Jim O’Sullivan told the Commons Transport Select Committee last year. 

Many don’t know that they can use the hard shoulder, others worry about sudden speed limit changes. However, it was recently revealed that smart motorway cameras give a one-minute grace period to drivers after a reduction in limit on the overhead gantries.

Smart motorways: is there a future for them?

smart motorway speed cameras one minute grace period

There is a consensus, generally, that a couple of things need to occur to make smart motorways safe.

Firstly, drivers need to know how they work, and how to use them. And secondly, all-lanes-running necessitates more frequent refuge areas, plus better stopped-vehicle detection.

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