All you need to know about smart motorways

All you need to know about smart motorways

What is a smart motorway?

Smart motorways are part of a government scheme – where the hard shoulder is used by vehicles as a running lane and the flow of traffic is controlled by variable speed limits – and are becoming increasingly common place throughout England.

Highways England (previously the Highways Agency) has developed smart motorways to increase motorway capacity and reduce congestion in a way that minimises environmental impact, cost and time to construct by avoiding the need to build additional lanes. There are three types of scheme which are classed as smart motorways – controlled motorway, dynamic hard shoulder running and all lane running.

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What different types of smart motorway are there?

All lane running schemes

As the name suggests all lane running smart motorways use the hard shoulder permanently as a running lane for traffic.

On Monday 14 April 2014 eight miles of the M25 between junctions 23 and 25 became England’s first smart section of motorway with traffic running permanently on a new running lane that was previously used as the hard shoulder and a further section of the M25 between junctions 5 and 6 opened a few days later.

Under all lane running schemes, lane one (formerly used solely as the hard shoulder) is only closed to traffic via overhead and verge mounted cantilever signs, in the event of an incident. On these sections broken white lines between all lanes indicates that each lane has the same status.

Just as in the dynamic hard shoulder schemes, overhead gantry signs display the mandatory speed limit which varies depending on the traffic conditions and speed cameras are used to enforce these. Signs can also be used to close lanes should that be required.

If an incident occurs in lane one – formerly the hard shoulder – a red cross (X) symbol is displayed to let motorists know the lane has been closed to traffic. Driving in a lane under which the red X symbol is being shown is illegal and could lead to you being prosecuted.

CCTV is used extensively to monitor traffic for any incidents. Should drivers break down or be involved in an accident there are emergency refuge areas at the side of the carriageway for them to use. These are typically further apart than current sections of motorway operating the dynamic hard shoulder running configuration, with an average spacing of 1.5 miles apart.

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Controlled motorway

Controlled motorways have three or more lanes with variable speed limits, but retains a hard shoulder. The hard shoulder should only be used in a genuine emergency.

Dynamic hard shoulder running schemes

Dynamic hard shoulder running involves opening the hard shoulder as a running lane to traffic at busy periods to ease congestion. The scheme, which was initially developed on the M42 in the Midlands, is now in operation on sections of the M42, M1, M6, M4 and M5.

On these stretches a solid white line differentiates the hard shoulder from the normal carriageway. Overhead signs on gantries indicate whether or not the hard shoulder is open to traffic. They also display the mandatory speed limit which can vary according to the traffic conditions. Speed cameras are used to enforce the variable speed limits.

If an incident occurs in lane one – formerly the hard shoulder – a red X symbol is displayed to let motorists know the lane has been closed to traffic. Driving under a red X sign is illegal. The hard shoulder must not be used if the signs over it are blank or display a red X, except in the case of an emergency.

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CCTV is used extensively to monitor traffic for any incidents. Should drivers break down or be involved in an accident there are emergency refuge areas at the side of the carriageway for them to use.

I've broken down on a smart motorway - what do I do?

We have full advice on what to do in the event of a breakdown on a smart motorway. You might also want to refer to our general motorway breakdown advice.