A modular suspended pavement system is helping civil engineers, landscape architects and urban designers foster the growth of large shading trees in tough urban environments.
The Silva Cell holds large amounts of lightly compacted soil to support tree growth ,while also supporting traffic loads beneath paving. In addition, it provides powerful and essential on-site storm water management through absorption, evapotranspiration, and interception.
92% of the Silva Cell frame can be filled with soil, providing a highly efficient soil volume for root growth and significant storm water treatment. By comparison, most structural soil mixes are just 20% soil, meaning a much greater area must be used to achieve the equivalent amount of soil volume.
The Silva Cell, as the system is known, is made of an ultra high-strength compound of glass and polypropylene, with galvanized steel tubes to add support and prevent plastic creep. They can be stacked one, two, or three units high before they are topped with a deck.
In the US state of Ohio, the governor wanted to make fairgrounds more attractive to visitors and more park-like. The issue was that blacktop – asphalt concrete – covered much of them.
Trees planted in a blacktopped area usually don’t thrive for more than a few years because the soil under the blacktop becomes compacted. Roots cannot push their way through the soil, and air and water can’t get to the roots.
With the help of the new technology, nine trees stretch through the middle of the northern end of all the state fairgrounds creating a boulevard 300 feet long.
The trees, a mixture of northern red oak, hackberry, river birch and honeylocust, should reach 60 feet tall with a canopy spread of 70 feet.
In addition to providing shade, the new installation will help storm water drain off the blacktop, solving another problem common to large paved areas. The grid of cells can hold about 20,000 gallons of water, equivalent to an inch of rain falling in an hour-long period on three-quarters of an acre.
The new technology is now providing similar solutions across the world in other harsh urban environments such as city centre plazas and car parks.