Highway to nature-based solutions

Nature-based solutions as a highways service offering is developing traction, and the evidence that nature can deliver benefits for road operators and their customers is mounting, say Julia Barrett and Shawn Gubbin.

In 2018, UK environmental regulator, the Environment Agency, compiled an evidence-base of employing natural processes. It found that using the right combination of measures in the right places can help to slow flood peaks and reduce the depth and duration of flooding.

On their own, NFM schemes are often cheaper and quicker to implement than traditional flood management techniques. But they do not have to be used in isolation. Installing them in conjunction with conventional concrete flood barriers, for example, can deliver higher levels of flood protection for highways infrastructure.

NFM techniques reduce the reliance on carbon-intensive materials such as concrete and steel, and as the vegetation matures it will remove carbon from the atmosphere through sequestration. In addition, the creation of new wildlife habitats will increase biodiversity in the area.

On the 5.6km Bexhill-Hastings Link Road, our team was instrumental in developing opportunities for enhancing biodiversity and landscape value across the Combe Valley, and for ensuring that environmental impacts were adequately mitigated. Our solutions have successfully delivered biodiversity net gain through new habitat for a wide range of species including invertebrates and overwintering and breeding birds.

Climate change will bring more extreme weather, flooding and rising temperatures, potentially damaging and disrupting vital infrastructure. Transport networks are particularly at risk and the sector must find solutions to help adapt to and mitigate the threat.

Given the carbon footprint associated with transportation, the sector has also been under the environmental spotlight.

Meeting national and global climate, carbon and wider sustainability goals, including limiting damage and enhancing biodiversity and our ecosystems, requires coordinated action, together with changes to transport policy and technical innovation.

Nature has a vital role to play, and nature-based solutions can be the next big shift towards infrastructure which works with nature to better adapt to, and mitigate against, the impacts climate change and biodiversity loss will bring. Additionally, solutions such as these also deliver significant multifaceted co-benefits such as flood alleviation and longer-term resilience.

Stopping the flood

Flooding is a major climate risk for road networks in many countries. Natural flood management (NFM) infrastructure is a good example of the diverse benefits a single nature-based response can deliver.

Woodland creation schemes intercept overland flow of water and encourage infiltration and storage within the soil, trapping floodwaters before they can reach the roadside; whilst the integration of wetland grassland habitat and reedbeds into the landscape can provide valuable flood attenuation as well as reducing downstream flood risk.

Similarly, we are currently designing for the enhancement of a 6km section of watercourse near a major road improvement scheme as part of the drive to deliver Biodiversity Net Gain. Using a multidisciplinary approach comprising of flood risk specialists, ecologists, landscape architects and geomorphologists, the project aims to deliver 24% net gain for biodiversity. Additional benefits include improved flood resilience for local infrastructure and the communities downstream of the intervention, enhanced ecological connectivity, an increase in amenity value, and carbon sequestration – which will all result from this nature-based solution.

Longer-term resilience

To maximise the beneficial environment, social and economic outcomes, nature must be brought to the fore at the scheme outset. This would enable enhancements to be made to marginal or unrealised benefits for local communities and add to the co-benefits and overall sustainability of a road scheme.

We have started to introduce this process on some of our National Highways schemes by hosting dedicated nature-based solution workshops at the early stages of a project with the client and contractor. It enables participants to share and collaborate on the nature-based solutions that can be embedded at each stage of National Highways’ development framework for a major project.

By embracing natural solutions more widely, we are confident the highways sector can experience dramatic cost-savings, while contributing to broader environmental and social gains.

Julia Barrett

Global practice lead for environment

The benefits may not be entirely as anticipated. For example, the creation of woodland and grassland areas as part of a highway scheme to aid landscape integration and reduce visual effects, also has co-benefits that lower the environmental footprint and help achieve sustainability goals, such as biodiversity net gain.

As part of our work on the A3 at Hindhead in Surrey, a road that was notorious for congestion and negatively impacting nearby environmentally sensitive sites, we integrated a range of measures and design features that enabled the recreation of a natural landscape. The regeneration of heathland habitat and the introduction of safe cycleways, and walking routes has greatly improved the tranquility of the area and seen the return of rare and diverse breeding birds, such as woodlarks and nightjars.

A greener future

We have decades of experience across relevant sectors, including infrastructure, environment, flood management and the built environment, and have developed market-leading digital tools, such as Moata Carbon Portal, to help road operators to reduce their carbon and environmental footprints and help regenerate natural landscapes.

By embracing natural solutions more widely, we are confident the highways sector can experience dramatic cost-savings, while contributing to broader environmental and social gains.