Re-Thinking the Sidewalk

tree_rootsby James A. Bacon

The vast majority of sidewalks in my home town, Richmond, Va., are made of concrete slabs. Concrete materials are inexpensive and the sidewalks are easy to install. But in a burg like Richmond, where people dearly love their trees, concrete pavement presents a problem. Tree roots lift or crack the slabs, creating hazards for pedestrians. Replacement can get costly — as much as $35 per square foot in Los Angeles.

So, the race is on to re-think the humble sidewalk, reports the Atlantic City Lab. Is it practicable to use other materials? Can sidewalks be integrated into storm water management systems? Can they be used to generate energy? Is their sole function to enhance walkability?

Some locales have run underground tubes carrying hot water under sidewalks to keep them clear of snow and ice. Others are tinkering with ways to convert the kinetic energy of footsteps into electricity, which can be used as an off-grid power source. Yet others are replacing concrete with recycled, hard-rubber mats that bend and buckle under tree roots without cracking. One English university is working on a self-healing sidewalk.

Senior Land Use Planner Eric Selbst at the site of the walkable solar paneled pathway. Photo credit: GWU.

Senior Land Use Planner Eric Selbst at the site of the walkable solar paneled pathway. Photo credit: GWU.

Another cool experiment is taking place in George Washington University’s Loudoun County, Va., campus. In 2013 the university completed what it billed as the first walkable, solar-paneled pathway in the world. Under ideal conditions, the sidewalk between Exploration and Innovation halls generate enough electricity to power 450 LED pathway lights below the panels. The university hired a Spanish company, Onyx Solar, to install the solar sidewalk. The installation generated dozens of  headlines — “Walking on Sunshine” may be the best —  but the media has been remarkably uninterested in following up.

My questions: What was the cost to install such a sidewalk? How much money will it save by eliminating the need for lighting? How well have the solar panels held up? What happens when tree roots grow underneath? What are the ongoing maintenance costs?

While scientists and engineers dabble with new materials and technologies, the more important question may be to ask what sidewalks are for. Do they serve a purely utilitarian function of allowing pedestrians to get from Point A to Point B? Or should we take a broader view of sidewalks as critical elements of the public realm? Sidewalks help define the public space along a street. Wider sidewalks create space for benches, restaurant tables, planters, trash receptacles and other public furniture. A well designed sidewalk can make a place inviting, a poorly conceived sidewalk can ruin a place.

We take sidewalks utterly for granted. They deserve a lot more thought and consideration than we give them.