The Sidewalk of the Future Is Not So Concrete

[M II A II R II K]

The Sidewalk of the Future Is Not So Concrete


May 22, 2014

By NATE BERG



Read More: http://www.citylab.com/tech/2014/05/...ncrete/371377/

Concrete has long been the go-to material for sidewalks because it's strong and cheap. The typical stretch of walkway can last decades; New Jersey sidewalks have an estimated lifespan of 75 years. But concrete has its drawbacks, too, especially for cities intent on improving walkability. Tree roots can crack concrete, creating hazards for pedestrians (especially wheelchair users and parents pushing strollers), and the more a tree grows the more its surrounding sidewalk swells. Frequent replacement can get costly — about $35 per square foot in Los Angeles — and self-healing concrete exists more in theory than in practice.

- Snowy cities from New York to Minneapolis have begun experimenting with heated sidewalks. Though typically poured with traditional concrete, these sidewalks are embedded with a vascular system of tubing that carries heated water, warming the surface just enough to melt snow and ice. The systems are expensive; costs can climb over $100,000 for a stretch of heated sidewalk in front of an apartment or at a train stop. But as both doormen in New York and local officials in Minneapolis can attest, the melted snow greatly reduces the need for shoveling as well as the hazards of slipping.

- A U.K. company called Pavegen has created a recycled rubber paving tile that converts the pressure of pedestrian footsteps into kinetic electricity. The tiles have been installed in train stations, playgrounds, and offices throughout the U.K. and France, and are used as an off-grid power source for street lamps, harvesting the energy of thousands of footsteps. Sidewalks can be a source of passive energy, too. Last fall, George Washington University's Virginia Science and Technology Campus, in Ashburn, unveiled "Solar Walk," a 100-square foot section of walkable solar panels.

- Another sidewalk company, Pro-Teq Surfacing, has gone even more passive by creating a spray-on substance that can make walkways glow in the dark. The material absorbs and stores UV light during the day and releases it at night, creating a spacey blueish glow. The company has started to test its spray on a small section of walkway in a park in Cambridge, England.

- But the most common new sidewalk technology is the flexible rubberized sidewalk. Often composites of old tires and recycled plastics, these rubber-based materials aim to counteract the destruction tree roots cause to concrete slabs. The city of Santa Monica, California, has been a leader in adopting rubberized sidewalks since 2000, and many other U.S. cities have followed. The rubberized panels, manufactured by Southern California-based Terrecon Inc., are secured to each other as well as the ground, offering a smoother walking surface with fewer gaps between panels for people to trip on. There's an estimated 20,000 square feet of rubberized sidewalk throughout the city today.

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Rubberized sidewalks in Santa Monica bend but don't break from tree roots. (Nate Berg)






Pavegen panels at the Saint-Omer train station, in Northern France. Via Pavegen