What are the best ways to incorporate green infrastructure into highway design projects?

1 Benefits of green infrastructure

Green infrastructure can offer numerous benefits for highway design projects, such as decreasing the amount and intensity of stormwater runoff, which can cause flooding, erosion, and pollution of waterways and habitats. Additionally, it can improve water quality by filtering out sediments, nutrients, metals, and other contaminants. It can also enhance the biodiversity and habitat value of the roadside environment by providing vegetation, wildlife corridors, and ecological connectivity. Moreover, green infrastructure can mitigate the effects of climate change by reducing greenhouse gas emissions, increasing carbon sequestration, and moderating urban heat island effects. Finally, it can create more livable and resilient communities by improving the aesthetic, recreational, and health aspects of the highway landscape.

2 Types of green infrastructure

Green infrastructure can be classified into two main types: green stormwater infrastructure (GSI) and green transportation infrastructure (GTI). GSI refers to the practices and systems that manage stormwater runoff at its source, such as rain gardens, bioswales, permeable pavements, green roofs, and rain barrels. GTI refers to the practices and systems that integrate natural elements into the transportation network, such as vegetated medians, buffer strips, roadside trees, wildlife crossings, and green bridges.

4 Design examples

Examples of successful highway design projects that incorporate green infrastructure can be found both domestically and abroad. For instance, the I-35W Stormwater Reuse Project in Minneapolis, Minnesota captures and treats stormwater runoff for irrigation and landscaping, while the I-90 Snoqualmie Pass East Project in Washington State includes wildlife crossings to reduce wildlife-vehicle collisions. The M6 Toll Road in England is home to a green bridge that spans over the highway, providing a habitat for plants and animals, as well as a scenic amenity for drivers and pedestrians. Additionally, the N329 Road of the Future in the Netherlands utilizes solar panels, LED lighting, and noise-reducing pavements to create a sustainable and innovative highway.

5 Resources and tools

If you want to learn more about how to incorporate green infrastructure into highway design projects, the Federal Highway Administration (FHWA) has a website dedicated to this topic, where you can find information, case studies, webinars, and publications. The American Society of Civil Engineers (ASCE) has a manual of practice on green streets, highways, and development with guidance, principles, and examples. Additionally, the Center for Neighborhood Technology (CNT) has a green infrastructure toolkit with tools, calculators, and models to help you plan and design projects.

6 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?