Vision and validate: a third way in designing the roads of the future

A map of the UK's smart motorway system (as of 2017) built from publicly available data of constructed and planned smart motorway systems.

1 Introduction
2 Strategic Road Network overview
3 Smart motorways under the microscope
4 Why we need smart motorways
5 We must improve communication
6 Setting out our vision for the safest, greenest and most reliable network
7 Related articles on Designing Buildings Wiki
8 External resources

[edit] Introduction

ICE Fellow Jonathan Spruce outlines the key messages and evidence on smart motorways he delivered to the Transport Select Committee in June 2021.

[edit] Strategic Road Network overview

The Strategic Road Network (SRN) is the backbone of the road network in England. The UK’s road network is a fundamental part of our transport system; all journeys start on a road or pavement of some form.

The functioning of the SRN is critical for the economy. Entire sectors depend on it, with some of the most dependent including retail, primary materials, manufacturing and construction. Thirty percent of all traffic is carried by the SRN road; inefficiencies, in the form of congestion, negatively affect productivity, the environment and quality of life.

[edit] Smart motorways under the microscope

In recent years, there has been a move to enhancing the capacity of the SRN by introducing so-called ‘smart’ motorways. This is either in the form of dynamic hard shoulder (DHS), where the hard shoulder is used as a live running lane at times of congestion or to deal with incidents, or all lane running (ALR), where the hard shoulder is permanently converted to a live running lane.

However, high profile fatalities on sections of smart motorways, and media coverage of their apparent safety, led to a pause in the rollout of smart motorways. In 2021, an inquiry into smart motorways was launched by the House of Commons Transport Select Committee, to which ICE submitted written evidence.

Examining how, as engineers, we can learn lessons and develop smart motorways in a safe and sustainable way in the future, were the key themes of the evidence I presented before the committee in June 2021.

[edit] Why we need smart motorways

As the UK’s population grows to 75 million people by 2050, the effectiveness of the SRN and its ability to cope with increased demand, while decarbonising to meet the 2050 net zero target, will help to define how successful the UK’s economy and society will be.

There is a projected increase in traffic of up to 59% on the SRN by 2050. Even in a post-COVID-19 situation, there will still be an increasing demand for travel on the SRN. Indeed, the shift towards online retail, and the lack of a realistic rail-based alternative for freight at this time, may even increase that demand further in the short term.

So, if we need the SRN to support our recovery from the pandemic, surely we should be looking to increase capacity on the most heavily stressed part of our network, in the most time and cost efficient way possible.

It has been significantly more time and cost effective to implement smart motorways as opposed to building new lanes. Smart motorways usually sit within existing highways boundaries and therefore:

Do not require additional land purchase.
Have a minimal impact on adjacent stakeholders, such as residents.
Do not require the widening of associated infrastructure, such as bridges, and have overall less environmental impact.

Evidence gathered by Highways England shows that smart motorways have relieved congestion and delivered journey time reliability benefits more efficiently. Department for Transport data shows that a smart motorway can carry an additional 1,600 vehicles an hour in each direction.

So the concept of smart motorways as a tool to address network congestion is sound. Potentially, it is in the application of smart motorways that some of the issues we have seen recently have arisen.

[edit] We must improve communication

There is potential confusion arising from a lack of consistency between DHS and ALR improvements. There is also an issue with different standards applied to the spacing of emergency refuge areas as well as the provision of stopped-vehicle detection.

However, one of the biggest failings of smart motorway rollout is the limited public communication of what smart motorways are, how to drive on them and the expectations of what to do in an emergency. This is exacerbated when such a large proportion of those driving never actually drove on a motorway as part of their driving test, let alone a smart motorway.

Public communication must be improved. It is positive that Highways England are improving in this regard, as can be seen by their safety campaigns.

It is imperative that drivers have the confidence to know they will be protected from traffic if they suffer a breakdown in a live lane. More emergency refuge areas and better technology must therefore be of utmost importance in continued smart motorway rollout and retrofit.

Learning lessons and adapting design is an important part of the engineer's role. Indeed, it is worth pointing out that the first motorways didn’t even have a central reservation barrier - just a patch of grass. This was a position that we learned from and corrected pretty quickly.

[edit] Setting out our vision for the safest, greenest and most reliable network

Maybe the point behind this issue is a wider one about how we approach our infrastructure. The ‘predict and provide’ approach to transport that we have adopted previously does not always address the root causes of congestion. It induces traffic, and thereby increased carbon emissions from transport, resulting in it being the largest emitting sector of greenhouse gases in the UK.

There is also the slightly wider ‘decide and provide’ approach, with policy measures to support a healthier and a net zero compliant transport system, measures to support modal shift to public transport and measures to reduce car miles travelled and the need to travel overall. This is a major step forward, but it may be more applicable in urban areas than on the strategic transport arteries that underpin our economy.

So I would offer a third way. A ‘vision and validate’ approach, whereby we set out our vision for the safest, greenest and most reliable SRN that we need for our future needs. We then use the amazing talent at our disposal across the engineering community to deliver that, embracing technology and new funding models (as identified in an ICE policy paper on post-COVID funding).

To me, that is the approach that we should be taking, allowing us to lead the world in delivering a safe and sustainable road network, and allowing social, cultural and environmental value needs to be better accounted for in the wider built environment. We should never stand still in our learning and adapting our knowledge and approach.

This article originally appeared on The Infrastructure Blog portion of the ICE website. It was written by Jonathan Spruce, ICE Fellow and published on 17 June 2021.

--The Institution of Civil Engineers