Nature-based solutions for surface transportation: four essential considerations

Transportation infrastructure is essential for societal connectedness and economic development, but its introduction can have significant impacts on nature. As the world addresses the challenges of climate change, biodiversity loss, and social inequality, there is an urgent need to transform the way we plan, finance, and deliver our infrastructure projects.

Our ‘Sustainable Legacies’ lead for the western United States (U.S.), Kristin Tremain Davis, and our global transportation ESG lead, Diane Cowin, explain how nature-based solutions (NbS) can help to minimize the impact of surface transportation infrastructure.

Effectively incorporating nature into infrastructure

Understanding the impact of an infrastructure project on nature goes well beyond the way a development affects local habitats and biodiversity. Stakeholders also need to consider how that project will affect the local human communities. They will need to look at the financial and insurance risk, and how the environmental aspects of a project affect potential funding sources. Financial institutions, insurers, project owners and developers need to think about all these elements and make informed decisions around nature at the earliest stage, including seeking out opportunities to integrate nature into the design.

Both the public and private sectors are now considering the broader environmental context of designing and implementing infrastructure projects – beyond regulation and employing nature as a more holistic solution. Several newly launched initiatives are aimed at encouraging developers and engineers to use nature-based solutions, integrating natural processes and systems into infrastructure programs to the benefit of all.

In the U.S., initiatives like Engineering with Nature’s International Guidelines on Natural and Nature-Based Features and the U.S. Government’s Earth Day EO14072 have recently come online, leading to the first National Nature Assessment. In the United Kingdom (U.K.), the Environment Act 2021 introduced mandatory biodiversity net gain for many development projects. The release of recommendations from the Taskforce on Nature-Related Financial Disclosures (TNFD) has also encouraged corporations worldwide to integrate nature into their decision-making .

Moving people, protecting nature

The balance between human mobility and environmental protection has long been a delicate one. The challenges in terms of climate change and biodiversity loss are becoming increasingly acute. However, by adopting nature-based solutions the needs of both humanity and the environment can often be aligned.

The best way to make existing surface transportation more resilient to climate change is to factor in the natural systems functions, moving beyond a regulatory compliance lens toward a broader nature opportunity lens. This means designing projects that work together with nature and enhance the inherent community and ecosystem value.

Bringing it all together

To bring nature-based solutions for surface transportation to life, we offer four interconnected considerations:

1. Social value.

Improving human well-being – this can include health and economic benefits, safety, climate resilience and even the simple enjoyment of our natural environment.

In the U.S., Resilient 37 was tasked with addressing congestion on Highway 37 in California, an area prone to occasional flooding. The ultimate design alternative incorporates a 9-mile (14.5 kilometer) causeway allowing space for rising sea levels and habitat transition through this protected landscape. The planning process has also allowed consideration for the addition of bicycle, pedestrian, transit and carpool options.

2. Ecological gain.

Nature-based solutions can reconnect habitats for plants and wildlife, employ nature’s evolved toolkit for adaptation, such as mangroves and wetlands, and provide wildlife corridors and safe passage for wildlife— from salamanders to mountain lions.

Highway 17 Wildlife and Trail Crossings, California, U.S. is a project developing a large wildlife undercrossing and pedestrian overcrossing through the four-lane Highway 17 in the Santa Cruz Mountains. The project creates habitat connectivity for humans and large mammals, including mountain lion and deer, while improving motorist safety by reducing animal-vehicle collisions.

3. Natural resilience.

Nature can be used alongside traditional engineering measures to improve biodiversity and enhance the resilience of transport corridors, with even small design adjustments having a major impact. For instance, building wildlife-friendly retention ponds (bio swales) to collect runoff at transit stations, or coastal protection from storms and wave events through the restoration of coastal habitats such as wetlands, mangroves, and mudflats.

The 13.6-mile (22-kilometer) Mumbai Trans Harbor Link connects Mumbai with its satellite city, Navi Mumbai, and once complete, will be the third longest bridge in the world. It will significantly reduce congestion and enhance connectivity, giving economic opportunity for communities in the region a welcome boost. Its height was designed to be clear of the Siberian flamingos’ annual migration path, and its construction protected mangroves and surrounding mudflats, which provide natural defense.

4. Alternative funding.

Cost can be seen as an issue for nature-based solutions. However, finding common goals can open finance options. Environmental benefits often translate to social benefits, particularly in disadvantaged communities, which can increase value in the area and widen the potential for further funding.

In the Philippines, we’re working with Conservation International to support 11 cities and municipalities in developing nature-based solutions to build resilience among vulnerable communities. One of the proposed projects is a national coastal road in Borongan City that will employ NbS to mitigate damage caused by flooding and storm surges, which will protect local homes and businesses as well. The project would generate jobs associated with mangrove rehabilitation, improve the livelihoods of local small-scale fishermen, enhance marine biodiversity and increase the potential for future investment in the area.

A commitment to the natural world – making it count

To design nature-based solutions that secure buy-in from all interested parties, planners and engineers must work together with ecologists, transportation experts and other stakeholders — from environmental groups to state legislatures.

Numerically assessing biodiversity impact allows us to understand the true effect of infrastructure on nature, enabling more sustainable design and helping projects become biodiversity positive. That’s why as part of our role leading the Sustainable Markets Initiative’s Measurement and Transparency Hub we’ve built a first-of-its-kind digital tool, powered by AI, that will gauge the impact of potential infrastructure projects on nature.

We’ve also collaborated with FIDIC (the International Federation of Consulting Engineers) and the WWF to create the Playbook for Nature Positive Infrastructure Development. The Playbook highlights how nature-based solutions can be integrated into infrastructure projects to make sure nature and biodiversity are kept at the heart of decision-making and design .

To find out more about surface transportation projects using nature-based solutions, please get in touch | Sustainable Legacies | AECOM.