Smart Motorways - A risk worth taking?

In 2004, a report from the National Audit Office criticised the Highways Agency for lack of innovation by not introducing hard shoulder running on UK motorways, citing the successful use of such schemes in The Netherlands and Germany. Its implementation soon followed with the first UK scheme known as the M42 Active Traffic Management (ATM) pilot. This used overhead gantries at 500m spacing along the carriageway and upon which were mounted Advanced Motorway Indicator signs (AMIs) above each lane to indicate its status. When appropriate to do so (based on a number of criteria), the hard shoulder could be opened as a running lane, indicated by text on MS4 matrix signs and the presence of a speed limit sign on the AMI over the hard shoulder.

Hard shoulder running is supported by emergency refuge areas (ERAs) at regular intervals and technology to manage and monitor traffic flows and respond to incidents. When variable speed limits are in place but the hard shoulder is not open to traffic, a red X is shown above the hard shoulder as shown in the picture below taken from the MM-DHS Concept of Operations document (MM-DHS: Managed Motorway – Dynamic Hard Shoulder).

A red X indicating that the hard shoulder is not available as a running lane on the M42 ATM pilot scheme.

My first project at TRL back in January 2004 was related to the M42 ATM pilot, testing the concept in a driving simulator as part of the safety case for the scheme ahead of its real world debut. It evaluated the effectiveness of the red X symbol to indicate that the hard shoulder was not available to traffic as a running lane (compared to a blank AMI). Whilst the observed behavioural differences were slight, participants subjectively preferred the clearer reinforcement of lane status afforded by the use of the red X. This was part of a programme of work that TRL delivered alongside projects awarded to other contractors to help Highways England evaluate and refine the concept.

The ATM pilot scheme evolved into a broader concept for wider implementation called ‘Managed Motorways’, which then became known as Smart Motorways. The motorway designs also evolved. Rather than opening the hard shoulder as an active traffic lane, more recent Smart Motorway schemes see the hard shoulder permanently converted into a running lane so that a three-lane motorway with hard shoulder becomes a four-lane motorway with emergency refuge areas (ERAs). Instead of using gantries and matrix signs to indicate that the hard shoulder is open, these technologies are used to indicate circumstances in which a lane (or lanes) are closed – such as the presence of a stopped vehicle in a live lane. Rather than DHS, these are known as ALR schemes (All-Lane Running).

With the recent appearance of Highways England representatives in front of the UK House of Commons Transport Select Committee, Smart Motorways have been in the news. There has been a sustained campaign from AA President Edmund King and others criticising smart motorways on safety grounds. In particular, the absence of the hard shoulder as a refuge for motorists breaking down meaning that a broken down vehicle unable to reach a refuge area can be stranded in a live running lane – with the obvious risk that other drivers unaware of the presence of the stopped vehicle may crash into it at motorway speed. By extension, this also poses a potential risk to recovery operatives tasked with rescuing vehicles in live lanes.

In the Select Committee hearing, Highways England Chief Executive Jim O’Sullivan indicated that he agreed with the suggestion that DHS schemes could be confusing for motorists. This is not surprising. When the majority of experience for UK drivers has been on conventional motorway designs, it can feel counterintuitive to then be permitted to cross the solid white line to use the hard shoulder – hence the preference for the ALR version in new schemes. O’Sullivan also indicated that he felt Highways England had not done a good job in educating drivers on how Smart Motorways schemes should be used.

Without the permanent presence of a hard shoulder, it is vital that obstructions on Smart Motorways are detected and that responses are instigated as quickly as possible. This includes closing affected lanes but also reducing speed limits and deploying Highways England traffic officers to help manage the situation. Whilst there is CCTV coverage and traffic monitoring technologies to support this, it is surprising that Stopped Vehicle Detection (SVD) systems were not a mandatory component of Smart Motorways from day one. Highways England’s August 2019 response to a Freedom of Information request by the AA highlighted that, whilst Highways England is committed to SVD on all ALR motorways, only 18% of ALR motorways (by length) have SVD in place. Indeed, chair of the Transport Select Committee, Lilian Greenwood MP indicated her surprise at the length of time it was taking to introduce SVD – to which O’Sullivan responded that this was due to the challenges in retrofitting this nascent technology to existing schemes and that Highways England is investing in innovations to help accelerate SVD deployment.

There are many reasons why the Smart Motorway approach makes sense. One argument is that modern vehicles are more reliable – certainly more so than when motorways were first introduced – so breakdowns are rarer. Therefore, there is the potential to gain road capacity but exploiting the underutilised asset represented by the hard shoulder. However, in the last five years, although there has been an increase in motorway vehicle miles travelled of 6.5%, there has been an increase in the number of vehicles stopping on the hard shoulder of 18.5%. In the Select Committee hearing, Chief Highways Engineer, Mike Wilson stated that up to 90% of stops on the hard shoulder are non-emergency purposes – including inappropriate uses such as toilet breaks, running out of fuel, reading a map and making a non-urgent call. Removal of the hard shoulder reduces the temptation of drivers to risk these improper stops. Genuine emergency stops within the ERAs are safer by giving greater separation from live running lanes and from the monitoring that can help manage traffic in the vicinity of the stopped vehicle.

Whilst motorways are our safest roads, they are not risk free. They are inhabited by a mixture of vehicle types driven by people of all ages with a range of different driving experience, in a variety of alertness states and some travelling at more than 30m per second and with a stopping distance the length of a football pitch. In the Select Committee hearing, O’Sullivan highlighted that although it may be more likely, breaking down in a live lane is not an exclusive occurrence on Smart Motorways. A sudden breakdown when travelling in the outside lane of a busy motorway could render a vehicle unable to reach the hard shoulder. Equally, breaking down on a dual carriageway without a hard shoulder, designated refuge areas or monitoring technologies presents a greater danger - yet drivers do not seem to hold the same negative perceptions for dual carriageways as they do for Smart Motorways.

One of the final questions raised by a member of the Select Committee asked why it is that Highways England gets to decide how risks are traded on the network – in this instance trading the predicted increase in collision risk with a stopped vehicle in a live lane on a Smart Motorway against the other safety gains that this road design delivers. O’Sullivan responded that the safety of the network and efficient use of public money are within the remit of Highways England and so it has to make decisions with those responsibilities in mind.

This question particularly struck me because, as O’Sullivan highlighted, the statistics indicate that Smart Motorways are no less safe than the safest roads on the network. Whilst we should address all sources of risk on our transport system, the scrutiny being placed on Smart Motorways is at the expense of considering the wider risks associated with road use – in particular, collisions on other parts of the network (of which there are many more) and the emissions caused by motor vehicles (the devastating impacts of which are being increasingly recognised). By continually singling out Smart Motorways, its critics fail to recognise that the risks and issues are greater on other roads. If they turned the spotlight onto those risks, they might reveal concerns that are much more troubling and which could challenge the deeply ingrained apparent centrality of the car as society’s preferred mobility option.

In my view, Highways England are doing a good job in delivering on the objectives that they have been set – including the implementation of Smart Motorways. Every collision is a failing, every road death a tragedy. However, given the evidence around the risks associated with their use, we should not focus on whether Smart Motorways are the right answer to the question of motorway network performance but whether we are asking the right questions in the first place.