The future is stashed under highways. A single intersection in San Antonio, like the one where I-37 and I-35 meet, can span more than a square mile. For context, that’s the same area as the Henry B. Gonzalez Convention Center, including its enormous additions. You could fit the San Antonio Museum of Art in that space more than six times, and that’s just one intersection. The vast majority of these roads are far above the ground level, and little is being done with the huge spaces under them.

Now, obviously not all of that space is ideal, but the size of these highways makes them a tremendous opportunity for strategic development. Without developing underpasses, highways bisect neighborhoods and waste huge swaths of the urban core.

Philadelphia artist Donald Lipski’s F.I.S.H. installation on the northern River Walk under Interstate 35. Photo by Scott Ball. Credit: Scott Ball / San Antonio Report

Already, some underpasses have been purposed as parking space (the Pearl), sculpture exhibitions (the Museum Reach), and light installations (Commerce and Houston Streets). Those are steps in the right direction, but they represent just a fraction of the total space available around the city, and they don’t include much innovation.

Here are five ways to make highway underpasses amazing:

Parks

The majority of underpass structures are reinforced concrete or galvanized steel, making them incredibly strong and capable of handling all sorts of abuse. Their stability and coverage make them an ideal location to house parks that feature all sorts of activities.

Toronto’s Underpass Park is a great model. At 2.5 acres, it contains basketball courts, a skate park, and a massive playground. The $9 million development is a bold attempt to use public space productively and connect neighborhoods that would otherwise be separated by a gritty, unpleasant divide.

Rock climbing walls also fit snugly under highways. In San Antonio, where there is a rapidly growing population of climbers with relatively few gyms, using public infrastructure could fill a legitimate gap. The Climbing Business Journal ranked San Antonio in the top 6 cities to open a climbing gym.

In Victoria, Australia, climbing walls have been installed under highways. Photo Courtesy of Burnley Bouldering Wall.

Venues

Streets are already heavily featured in Fiesta and Síclovía, which have helped connect residents with public space. Earlier this month, I had the opportunity to help throw a pop-up concert at a big empty warehouse, and attendees repeatedly told me that the space was the primary draw rather than just the music.

Lately, urban dwellers see themselves as explorers, looking to connect to their city by discovering and enjoying new places. The surge of pop-up dinners, sporadic concerts, and food truck parks is good evidence that if highway underpasses are framed as event space, opportunistic planners will make them amazing.

Gardens

Plants grown in underpasses could have substantial benefits for the rest of the city by performing vital environmental services.

Many highways are elevated primarily because of the flooding risk on the ground level during heavy storms, so equipping underpasses with plants that provide good drainage could help stem the tide of flash flooding in surrounding areas. Plants help urban drainage by increasing the soil’s permeability as their roots reach through the compacted surface.

Broadway looming under I-35 and US-281. Photo by Scott Ball.

Plants can also help residents breathe easier by filtering air. One recent study found that “Careful placement of grass, climbing ivy and other plants in urban canyons can reduce street-level concentrations of nitrogen dioxide by up to 40 percent and particulate matter by 60 percent.” As San Antonio struggles with air quality standards, localized vegetation under and next to the source of vehicle emissions could make a big difference.

Graffiti Gardens

Graffiti is a staple of highway underpasses, presenting a blank canvas for rebellious youth and wannabe gangsters. Some graffiti is inevitable, so why not allow it in certain places? District 1 Councilmember Diego Bernal has found that commissioning custom murals discourages would-be taggers because they don’t want to destroy great art.

Legal graffiti events like Clogged Caps have demonstrated serious talent by painting unique murals around the city, theming their works together to construct a holistic motif in each location. Designating a couple of underpasses as sanctioned graffiti havens would instantly create new public art installations.

Underpass Park also contains a mirror installation to make the space seem larger next to the playground. Photo Courtesy of Waterfront Toronto.

Smellscapes

This one is the hardest smell – er – sell, of the bunch. Every space has a smellscape; some are faint, others terrible. Smells affect our experiences even if we’re not always thinking about them. Some cities have taken note and are creating scent maps to identify different pungent spaces. Imagining highway underpasses as fragrant havens would be the ultimate transformation from the dingy and disgusting spaces they’re framed as now.

Spaces can be scented through flowers or artificial smell blasters (there’s even an app for it). Casinos already surround gamblers with the scent of vanilla to make them more comfortable, and movie theaters blast warm buttery popcorn aromas as soon as customers enter the door. As companies get more comfortable with manipulating consumers’ noses, cities should respond by actively constructing smellscapes for the public benefit.

A landscape designer from Houston, Andre Boudreaux, convinced me when he said, “Highways slice and dice neighborhoods into small, fragmented pods, and it’s important that we make an effort to connect our neighborhoods to form a cohesive urban fabric. We need spaces that are memorable, inviting and useful. Smellscapes could do just that.”

A sign pointing towards Broadway Street off an exit ramp under Interstate 35. Photo by Scott Ball. Credit: Scott Ball / San Antonio Report

These are just a few of the ways that unused space like highway underpasses can be repurposed to benefit the public. Many options require little to no capital investment, and there is no significant safety risk because they are under the speeding cars.

Underpasses are just one of many types of wasted space in San Antonio, along with rooftops, abandoned buildings, and empty lots, but one thing that distinguishes highways is that they already exist to connect vast areas. Creating great underpasses could do more good than the benefit of each individual renovation, because enabling residents to walk or bike under highways could change development patterns by making the entire city more accessible to pedestrians.

After completing his project, one of Toronto’s Underpass Park designers, Greg Smallenberg, said “The thing about all of this transportation infrastructure littering our cities is that it isn’t going away. As open-space resources continue to dwindle in our cities and urban populations and densities increase, we have to take advantage of whatever open spaces we have.”

To make it happen, the Transportation and Capital Improvements department could post an invitation for bids on www.SanAntonio.gov. Nearly every other month, it requests bids on park renovations, and they’re under no obligations to accept any bids. At the very least, requesting bids could incentivize designers to think about the possibilities of these public spaces.

Parking for The Pearl Brewery makes use of underpass space. Photo by Scott Ball.

*Featured/ top image:Part of Toronto’s Underpass Park includes basketball courts and a skate park next to the concrete support columns. Photo Courtesy of Waterfront Toronto.

This story was originally published on Thrusday, Oct. 30.

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