Smart motorways remain one of the UK’s most controversial road systems. Designed to reduce congestion and improve traffic flow, the modern smart motorway uses technology, variable speed limits and, in some cases, removes the hard shoulder entirely. But with growing safety concerns and increasing driver frustration, many motorists are asking whether smart motorways are actually safer or more dangerous.

In this guide, we explain what is a smart motorway, how they work, the meaning behind changing speed limits, and the latest safety statistics from the UK.

What is a smart motorway?

A smart motorway is a section of motorway that uses technology to manage traffic flow and reduce congestion. The aim is to improve journey times without widening roads. 

This includes:

• Variable electronic speed limits
• Traffic cameras and sensors
• Lane control signs
• Emergency refuge areas
• Hard shoulder running on some routes

The are three main types:

• Controlled Motorways: Retains a permanent hard shoulder but uses mandatory variable speed limits.

• Dynamic Hard Shoulder (DHS) Motorways: The hard shoulder opens as a normal live running lane during peak congestion times.

• All Lane Running (ALR) Motorways: The permanent hard shoulder is permanently removed and converted into a live running lane, with designated Emergency Refuge Areas (ERAs) spaced roughly one mile apart.

The UK government stopped building new smart motorways in 2023 following public safety concerns.

How do motorways work with variable speed limits?

Many drivers wonder: how does motorway work when speed limits keep changing? Smart motorways use overhead gantries displaying different speed limits depending on:

• Traffic congestion
• Accidents
• Weather conditions
• Roadworks
• Broken-down vehicles

These are known as motorway speed restrictions and are legally enforceable. The idea is to smooth traffic flow and prevent sudden braking, often called the “accordion effect.”

What is the national speed limit in the UK?

The national speed limit in the UK for vehicles on motorways is typically 50 to 70 mph depending on road type and vehicle. You can find out more of these here.

The familiar white circular national speed limit sign with a black diagonal stripe means the national speed limit applies. However, on smart motorways, the displayed speed limit on overhead signs overrides the normal motorway speed limit.

Are smart motorways safer?

This is where the debate becomes controversial.

National Highways maintains smart motorways are statistically among the safest roads in the UK overall. However, recent reports and driver surveys have raised serious concerns.

Recent  analysis of 16 smart motorway schemes found:

• Several routes showed worsening safety records
• Some sections had increases in serious collisions
• Many schemes delivered poor value for money

The research also found:

• Drivers who break down on smart motorways are three times more likely to be killed or seriously injured compared to traditional motorways with hard shoulders
• Driver anxiety around smart motorways rose from 23% to 46% in the past year

At least 79 deaths have been linked to smart motorway incidents between 2010 and 2024, according to reported figures.

Why are drivers concerned?

The biggest concern involves the removal of the hard shoulder on All Lane Running motorways. If a vehicle breaks down:

• Drivers may become stranded in a live traffic lane
• Emergency refuge areas may be far away
• Fast-moving traffic may have little time to react

Investigations have also revealed failures in smart motorway safety technology, including outages affecting cameras and warning systems.

Some drivers also complain about confusing or sudden motorway speed restrictions, particularly when there appears to be no visible danger ahead.

Understanding smart motorway speed limits

On smart motorways, overhead signs display variable speed limits such as:

• 60 mph
• 50 mph
• 40 mph

These limits are enforced by speed cameras.If no variable limit is shown, the normal motorway speed limit of 70 mph applies. Ignoring variable limits can lead to:

• Fines
• Penalty points
• Increased accident risk

What should you do in case of a breakdown?

If you breakdown on a smart motorway:

1. Try to reach an emergency refuge area
2. Use hazard lights immediately
3. Exit the vehicle from the passenger side if safe
4. Stand behind the safety barrier
5. Call emergency services or breakdown assistance

Drivers should never remain inside a stranded vehicle in a live lane unless instructed otherwise.

Reliable breakdown cover can be especially important on smart motorways. Want to learn more about CoverMy Breakdown?