The City and County of Honolulu is using a new, modular, suspended-pavement system to give trees more room to grow at the Waipahu Transit Center on Hikimoe Street.
City transportation officials today announced the installation of 500 Silva Cells — modular building blocks that sit directly beneath sidewalks and roads — in Waipahu.
The installation is part of a larger reconstruction project for the transit center amounting to about $1 million, which includes the 500 Silva Cells as well as 13 trees.
The modular blocks, made of compound resin, have spaces between them that can be filled with soil and space for the root systems of large trees. In addition, they help manage storm runoff.
Mayor Kirk Caldwell said the use of the Silva Cells technology is in line with his goal of planting 100,000 new trees within the next five years, and increasing the city’s urban tree canopy from 23 to 35% by 2035.
“As we renovate and redesign local areas, we’re taking into consideration innovative engineering as well as the environment, and Silva Cells fulfill both,” said Caldwell in a news release. “The installation of these cells will allow the 13 trees we’re planting at the Waipahu Transit Center to grow bigger with a wider canopy, creating more shade for those who are waiting at the bus stop as well as making the area look more beautiful.”
A typical sidewalk has minimal room for trees to grow due to the dense material used as a foundation, according to city officials, and their roots often stay close to the surface, causing damage.
Silva Cells are designed to give the trees’ root systems room to grow in the soil beneath while holding the weight of the sidewalk or street above. The expected result is taller and fuller trees.
The Silva Cells, manufactured by a California company called Deeproot, have been installed in many U.S. municipalities, including beneath the plaza at the Metropolitan Museum of New York.