There is no doubting the impact highway networks have on wildlife, and with new road construction showing no signs of slowing, this impact is likely to increase. Coupled with the urgency to address the effects of climate change, it is clear there is a requirement to re-think how we deliver road projects.

According to National Highways’ chief executive, Nick Harris, the industry is facing a period of rapid change, particularly when we look at the environment and emerging transport challenges. As such, the highways industry must turn its attention to new methods of construction, whether designing a new road or retrofitting an existing network.

How, then, can the industry consider both road users and nature? There are two opportunities to satisfy each:

1. Nature-based Solutions, where natural solutions are preferred over artificial ones, and
2. Sustainable Drainage Systems (SuDS), which considers sustainable management of water.

Nature-based Solutions help address the threat and impact of climate change, supporting conservation, restoration and enhancement of ecosystems and biodiversity. Crucially, they also help vulnerable populations adapt to climate change, including the impact on water and food security.

SuDS, meanwhile, allow transport infrastructure to facilitate and sustain better environments for both people and nature. The philosophy is centred around four key pillars: water quantity, water quality, amenity and biodiversity. The SuDS Manual (CIRIA C753) offers comprehensive guidance for planning, design, construction, operation and maintenance of water management systems.

Chapter six of the manual focuses on “Designing for Biodiversity,” highlighting the significance of habitats within SuDS schemes linking with other local and regional habitats to enhance connectivity and address problems associated with loss and fragmentation.

Within England alone, National Highways is responsible for over 30,000 hectares of land adjacent to the strategic road network. The importance of natural habitats around our highway networks is only going to increase. As such, following SuDS principles and using the mitigation indices to remove pollutants is set to become more crucial than ever in highway design.

There are many ways to utilise Nature-based Solutions and SuDS in both retrofit and new construction projects. Trees and green areas, for example, offer shade, amenity, natural air conditioning and refuge opportunities for wildlife. SuDS solutions, such as bioretention areas, rain gardens, swales and tree pits, take runoff from hard surfacing. Crucially, these can be coupled with drainage to underground tanks, where above ground space is a restriction. Space is often one of the key barriers when incorporating SuDS on site. Here proprietary solutions, such as oil and heavy metal separators, are beneficial, as they can help ease the pressure on natural systems. When the water is clean, it can then feed into natural systems.

Treating pollutants and protecting the natural world from the impact of human activity is vital. For Nature-based Solutions to flourish we must have a resilient, safe and clean supply of water and nutrients. This should be coupled with the sustainable management of water through SuDS, to ensure the future prosperity of natural systems and Biodiversity Net Gains.

For more information, visit www.aco.co.uk/sustainable-drainage-systems-(suds)

Terry Wilkinson- Specialist Design and Application Engineer, ACO Technologies