For most pedestrians, the sidewalk is an unnoticed facet of theeveryday streetscape, like a telephone pole, traffic signal, or postalbox. But the choices made about the materials to use for building andinstalling sidewalks can significantly affect the atmosphere of anurban environment.
For most American cities, concrete is the go-to choice for buildingsidewalks. It’s relatively cheap to install – only about $12 per squarefoot – and it’s very solid. Its pale color reflects light, reducingnighttime illumination costs for cities compared to darker-huedalternatives. Plus, if adequately maintained, concrete can last up to eighty years.
Yet concrete also has its downsides: Manufacturing it has a high carbon footprint,since its fabrication requires the energy-intensive heating oflimestone; it has a tendency to crack when tree routes grow underneathit; and it has no porosity, depriving the ground under it of essentialground water and increasing runoff problems.
As a result, cities around the world have invested in a number ofalternatives, to varying success. Asphalt – the stuff usually used forthe roadbed – is actually a cheaper option, but it’s seen as too poorlydifferentiated from the car path, putting pedestrians in danger. It’salso far more susceptible to damage in cold and wet weather.
Brick is a frequent choice in historic neighborhoods, since it givesoff the sense of craftsmanship and handiwork. But as a material for theaverage walker, it’s pretty miserable. It becomes incredibly slippery in the rain or snow and it breaks up easily over time. (That said, a broken brick is far less unsightly than a slab of cracked concrete.)
Other urban areas have invested in stone slabs and cobblestones – materials common in European cities like Paris (as shown in the picture above) – where they’re praised for their attractive looks and solidity. Toronto is currently replacing the sidewalkon one of its major corridors with granite, with the idea that a betterlooking sidewalk will encourage more people to walk around, and therebyincrease area property values.
But heavy stone like granite and marble is expensive to buy. In Beverly Hills, California, installation costs $850 a linear foot – far more than other materials. Some stones can even be a liability, since they become slippery more easily than concrete. And they trip up the movement of people who rely on mobility aids like walkers and wheelchairs, and need more even surfaces.
For now, then, concrete remains the most reliable option – and arelatively cheap one at that. Yet there may be a better future, and it’s made out of rubber.Several companies have developed sidewalk panels recycled from usedautomobile tires, saving material costs and reducing ecological impact.They have a high amount of porosity, limiting runoff and preventingarea flooding.
Per square foot, they’re just a bit more expensive than concrete.and they’ve already been installed in several American cities, including Seattle. Yet, they’re just as sad looking as a common concrete panel, doing nothing to enliven the street.
In the end, there may be nothing better than the textured,high-quality feel of the sidewalk stone so noticeable in Europeancities. It’s just so darned expensive!