Traditionally, the sheltered areas beneath highway and freeway overpasses are places of dereliction and decline. They are places where garbage gathers and the homeless seek refuge. Especially in car-centric cities, they are a blight foisted on us like an afterthought by traffic engineers.
Thankfully, planners and citizen advocates are beginning to transform areas beneath overpasses into a green future. Examples include projects such as Seart Park in Mount Wellington, New Zealand, Underpass Park in Toronto and Seattle’s I-5 Colonnade Mountain Bike Park.
A friend sent the above video of an urban naturalization project - the Via Verde project - recently launched in Mexico City; it modifies support columns beneath an elevated motorway using ivy and thousands of plants.
Although it's in Spanish, even non-Spanish speakers can see the video is inspiring! The main goal is ecological, namely cutting the air pollution problem from Mexico City’s notorious traffic congestion. The design structure uses recycled bottles, an automated rainwater irrigation system, and many other environmental innovations.
But there are obvious psychological perks worth mentioning from a SafeGrowth perspective.
The vegetative covering on cement pillars not only improves the color and aesthetics of a bland area, but it is just the kind of greenery that reduces the stress and foul moods from traffic madness. It also insulates against a wall of traffic noise, a major fear generator in urban places.
Then there are the social contributions, for example, parts of the structure were constructed by women penitentiary inmates who were paid for their work. If plants begin to yellow, local residents use social media to notify the city thereby encouraging citizens to claim an interest in underpass areas, further enhancing the natural surveillance.
To date there have been few examples of an environmentally based CPTED - the so-called 3rd Generation CPTED. That is a theory yet to emerge and the green underpass movement may be a perfect place to start.