Simon Tucker, Director at Pegasus Group, discusses what needs to change in road design regulations to roll out greener design techniques on the UK’s roads.

A New Way is Coming…

The UK’s sixth Carbon Budget set in law the goal of reducing emissions by 78% by 2035. If met, it will bring the UK more than three-quarters of the way to net zero by 2050. The Ten Point Plan for a Green Industrial Revolution puts more flesh on the bones, seeking to accelerate the commercialisation of low-carbon technologies and systems.

It’s as exciting as it is ambitious.

As the civil engineering industry pivots towards a greener future, new materials solutions – such as warm mix asphalts (WMA) and recycled aggregates – are emerging in the design and specification of road infrastructure.

National Highways is leading the way through collaboration with academia to reduce raw material consumption, reuse waste materials and explore new materials such as polymer modified bio-binders, artificial aggregates and even pollution-absorbing materials.

…But the Uptake is Slow

Roll out is far from widespread, and remains protracted, particularly at the Local Highway Authority (LHA) level. WMA represents less than 4% of overall asphalt production, even though it outcompetes hot rolled asphalt (HRA) for reduced carbon emissions and recycling potential.

What is stopping its mass roll-out?

The UK’s sixth Carbon Budget set in law the goal of reducing emissions by 78% by 2035.

A Lag Between Innovation at the National and Regional Level

Best practice for carbon management in infrastructure is that all stakeholders maintain open lines of communication from the outset. And National Highways is flying the flag for collaboration. Working with stakeholders including the Transport Research Laboratory (TRL), it is trialling new low-carbon construction techniques, and requiring designs for its trunk road network to be tested against a carbon calculator toolkit, to demonstrate lower carbon design.

But LHAs typically lack the resourcing – in money, time and skills – needed to keep up with a rate of change in innovation. LHAs could carry out their own trials, of course. But with such under resourcing, authorities typically wait for innovation to filter down from the national level.

Resource-Strapped Highway Authorities

As indicated above, most LHAs face a significant shortfall in maintenance budgets. While some are flying the flag for a greener future, funding levels in 2023 fell two-thirds short of what’s needed just to maintain existing roads. With a burgeoning backlog (£14bn), it will take 11 years to get local roads back into a reasonable condition.

Against this backdrop, it’s understandable that their top priority is value for money. Most specify traditional over innovative methods because their performance qualities and maintenance requirements are better known.

The Net Zero Innovation Portfolio £1 billion fund, announced in the Ten Point Plan by the current government looks at first glance to be the answer. But it’s unclear how much of that will be directed either into supporting our highway authorities, or into crucial R&D of low carbon materials. Instead, “thousands of miles” of segregated cycle lanes will be built, ironically, using traditional, high carbon materials. However, with the General Election looming, there remains uncertainty as to how this aspiration will be met.

But it’s not just maintenance budgets that have suffered. HAs have been deprived of the time needed to invest in upskilling and developing the in-house knowledge to embrace new low carbon design and construction methods, update specifications, implement and monitor road construction. Historically, highway authorities had their own material engineers and testing laboratories, however, cuts in funding have seen these disappear, resulting in a loss of knowledge at the local level.

Where specifications do allow for greener design techniques, departures from standard can invariably delay the granting of essential technical approvals and can attract higher commuted sum payments.

An Inconsistent Picture in Low Carbon Specifications

Under the current regulatory framework through which the LHA adopts a newly built road, the LHA prepares material specifications against which new roads must be built.

But as there is no requirement for highway authorities to include low-carbon specifications, innovation is patchy across the country. While some highway authorities do include greener construction methods, these are optional and the “lower risk”, more traditional approaches are typically favoured by developers.

Many specifications don’t include new low carbon methods as an option at all.

The Unknown Entity of Innovation

Where specifications do allow for greener design techniques, departures from standard can invariably delay the granting of essential technical approvals and can attract higher commuted sum payments. In a sector where time is money, developers often opt, understandably, for a traditional approach with the lowest risk, to secure timely approvals.

Many of our clients would like to take the high road and go green, but with viability and timescale pressures it is all too often not an option on an individual project basis.

It’s Time to Expedite Change

This dynamic needs to be broken if we are to innovate extensively and at pace. Change has to be driven from the top down, with central government effecting real change at the local level. To expedite the roll-out of low-carbon technologies, a nationally-coordinated effort to scale up trials is needed, with data managed and assessed by a national body such as the ADEPT.

We need to step away from local standards. Where often knowledge is weaker and budgetary restraints constrain manpower and skills. Yes, capital maintenance costs, safety and durability will always be critical metrics, but to this, we must demonstrate we are not just paying lip service to the climate change agenda. In the private sector, where the focus is on cost/risk and return, incentivising innovation is challenging as there is no ‘reward’. So, with no carrot, there is only the stick of imposed standards.

The Road to a Greener Future

If we are to see a significant increase in green techniques being rolled out on our roads, three things must happen:

  1. Local highway authorities must be on the same page. We need a new regulatory framework that provides a consistent approach to the selection of lower carbon materials, enabling national trials of new materials with performance data monitored against sustainability criteria. Rolled out on a national basis, and then brought into material specifications at the highway authority level, we would bring consistency to design specifications for adoptable road standards. Specifications should not merely allow for green techniques but require it.
  2. Highway authorities must be properly resourced to be skilled up and supported in rolling out a new wave of specification standards. Only then will we remove the obstacles that currently slow the process.
  3. More research is needed on the reuse and recycling of new materials, how properties will change over their design life and how to better predict when maintenance will be necessary to minimise resource use.

The industry is in a race against time to innovate and reduce its carbon footprint. We have an opportunity to employ the wider use of new materials, but it will require investment on a large scale, and buy in from all stakeholders.

With a legacy of underfunding and an ageing infrastructure, the challenge is an economic one. But if we fail to resource the sector properly, delivery will remain fragmented and opportunities to innovate will be missed, along with our net zero targets.

Find out more about how our Transport and Infrastructure expertise can help progress your project.

Simon Tucker is head of infrastructure at Pegasus Group’s Cambridge office, specialising in creating practical and sustainable design solutions for clients across the built environment.