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Smart Motorways: are they safer than traditional ones?

Smart Motorways have been gaining momentum in the UK over the last decade. At the same time, news about incidents in Smart Motorways has led drivers to question whether they are safer than traditional motorways. Many people still struggle to understand what Smart Motorways are and how to follow their safety rules. This article will discuss what Smart Motorways are and what the available data shows about their safety.

The current traffic situation on motorways

In 2018, the total miles driven in Great Britain were 328.1 billion, representing a 0.3% increase from the previous year. In the last 5 years alone, traffic on motorways increased by 9%, whilst this number has gone up by 62.9% in the last 25 years. Although motorways only represent 1% of the total road network length in Great Britain, they account for 21% of the total vehicle miles. With the Department for Transport (DfT) predicting up to 640 billion vehicle miles in the UK by 2040, whether on traditional asphalt or plastic roads, it is critical to think about smarter ways to manage the UK’s road infrastructure.

On the one hand, road accidents in the UK cost the government £35bn in 2017. On the other, congestion on motorways cost England £2bn per year. From an economic point of view, it is important to minimise road accidents and congestion. From a societal point of view, it is even more paramount to make roads safer. Every time an accident or a fatality occurs, there are hundreds of lives directly or indirectly impacted. Relatives, friends and colleagues suffer significantly when accidents happen. Because of all these reasons, Highways England has led a campaign to bring more Smart Motorways into the Strategic Road Network.

Types of Smart Motorway

The concept of Smart Motorway has actually been around for over two decades now. In fact, it was in 1995 when the first Controlled Motorway was open to traffic. Before we continue, let’s have a look at the different types of Smart Motorways:

  • Controlled Motorways (CM): these were the first Smart Motorways to be introduced in the UK. They added variable speed signs to traditional motorways, whilst retaining a permanent hard shoulder.
  • Dynamic Hard shoulder Running (DHS): this type of Smart Motorway was the next one to be introduced in the network. It includes new technology to measure and control traffic, with sensors and gantries with variable messages. This Smart Motorway has the peculiarity that the permanent hard shoulder can be turned into a running lane when necessary. The intelligent signs guide drivers when it is safe to use the hard shoulder as a running lane. There are emergency areas installed, similarly to the All Lane Running Smart Motorways, discussed in the following point.
  • All Lane Running (ALR): this type of Smart Motorway is the most recent one. Here the hard shoulder is permanently converted into a running lane. Newer technology and sensors constantly monitor traffic for congestion and accidents.

What are All Lane Running Smart Motorways?

It seems that the All Lane Running Smart Motorway has become the preferred type by Highways England. One of the key differences from a Smart Motorway compared to a traditional motorway is the presence of a concrete central barrier. This concrete barrier has been proved to be much more effective than traditional steel barriers to prevent accidents and improve safety. As the steel barriers in the central reserve are replaced by a single concrete barrier, additional space frees up in the motorway, which is used to increase the number of lanes by one for each direction.

Together with the hard shoulder, this space is generally enough to fit the extra lane, minimising the widening required to the motorway. Just by this ‘simple’ action of converting the hard shoulder into a running lane, the capacity of the motorway is increased by 33% at minimal cost. In order to control traffic congestion and monitor accidents, Highways England installs new technology. This includes sensors, cameras, gantries and variable message signs. Thanks to this technology, the operator can reduce the speed limit when vehicles are getting too close together.

Contrary to what this may suggest, reducing the speed limit actually helps reducing journey times and improving reliability. This is obtained by eliminating the accordion effect produced by the ‘stop and go’ that results from congestion. From a journey time perspective, it is better to go at a constant, lower speed, than having to stop and start again due to a traffic queue.

Why do we need Smart Motorways?

The main objectives of Smart Motorways are, therefore, to increase capacity in the Strategic Road Network and to reduce journey times whilst increasing reliability. And all of those objectives should be met whilst maintaining the same level of safety, or improving it. Evidence from the first Smart Motorway – the M42, which opened in 2006 – showed:

  • Journey reliability improved by 22%.
  • Personal injury accidents reduced by more than half.
  • When accidents occurred, the severity was lower, with zero fatalities.

Safety concerns after removing the hard shoulder

However, Smart Motorways still present many challenges for road users. It is necessary to change drivers’ behaviours on Smart Motorways to adapt to new safety rules. Many drivers are concerned about safety as a consequence of the removal of the hard shoulder. Official statistics show that 1 in 10 deaths on motorways occurs in the hard shoulder. Therefore, Highways England argues that by removing hard shoulders, they reduce the risk of fatalities. Emergency areas are also believed to be safer than hard shoulders, as they are segregated from traffic.

After public complaints about the distance between Emergency Areas (EA), Highways England decided to reduce the maximum distance from 2.4km to 1.6km. This way, drivers should see an Emergency Area every minute and a half maximum when driving on a Smart Motorway. A comparison between the M40, with EAs less than 1km apart, and the M1, with EAs up to 2.4km, shows that there is no correlation between the distance of EAs and live lane breakdowns. According to Highways England, adding EAs to existing Smart Motorways or making them wider would be very expensive. The same money could improve safety by replacing central reserve steel barriers by concrete barriers, which cost around £1M more per mile but perform significantly better.

Data about safety on Smart Motorways

The number of Killed and Seriously Injured (KSI) people on the Strategic Road Network fell by 7.6% in 2017. The Smart Motorway M25 Junctions 5 to 6 and J23 to 27 reduced journey times between 2 – 9%, depending on the direction of travel. It also showed a small reduction in collision rates. The M6 Smart Motorway which opened last year also collected evidence showing the new scheme saving drivers up to 40 minutes per week. This was the result of increasing the average speed from 50 mph to 66 mph. Additionally, collisions reduced by 30%, which means around ten collisions less per month.

The Smart Motorway All Lane Running Overarching Safety Report 2019, published by Highways England on December 2019, assessed safety on the first 9 Smart Motorway ALR schemes in England. The report shows a statistically significant improvement in personal injury collision rate and casualty rate. Both rates outperformed the national trend by 12% and 18%, respectively. Across the 9 schemes included in the assessment, they found an absolute reduction of 28% in the casualty rate.

Do you think Smart Motorways are safer than traditional motorways? Let us know your experience and opinion in the comments below!


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